ENANTIOSELECTIVE HYDROGENATION OF 4-SUBSTITUTED 1,2-DIHYDROQUINOLINES IN PRESENCE OF A CHIRAL IRIDIUM CATALYST

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The invention relates to a process for preparing optically active 4-substituted 1,2,3,4-tetrahydroquinolines comprising enantioselective hydrogenation of the corresponding 4-substituted 1,2-dihydroquinolines in presence of a chiral iridium (P,N)-ligand catalyst.

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Description

The invention relates to a process for preparing optically active 4-substituted 1,2,3,4-tetrahydroquinolines comprising enantioselective hydrogenation of the corresponding 4-substituted 1,2-dihydroquinolines in presence of a chiral iridium (P,N)-ligand catalyst.

It is known from EP 0 654 464 that N-acetyl-tetrahydroquinolines can be converted to the corresponding 4-aminoindane derivatives via a rearrangement reaction.

4-aminoindane derivatives are important intermediates for preparing various N-indanyl heteroaryl carboxamides having fungicidal activity (EP 0 654 464, WO 2011/162397, WO 2012/084812, WO 2015/197530).

EP 3 103 789 discloses a method for optically resolving 1,1,3-trimethyl-4-aminoindane by converting the enantiomeric mixture into the diastereomeric salts of D-tartaric acid. (R)- and (S)-1,1,3-trimethyl-4-aminoindane are obtained after separation and basification of the diastereomeric salts. This reference also discloses a method for racemizing the undesired enantiomer, so that the whole method allows for converting the undesired enantiomer into the desired enantiomer via several process steps. (R)-1,1,3-trimethyl-4-aminoindane is an important intermediate for preparing the pyrazole carboxamide fungicide inpyrfluxam.

A method for preparing chiral intermediates of N-indanyl heteroaryl carboxamides via asymmetric synthesis is also known. WO 2015/141564 describes a process for preparing optically active 4-substituted 1,2,3,4-tetrahydroquinolines, which process comprises the hydrogenation of the corresponding 4-substituted 1,2-dihydroquinolines in presence of a transition metal catalyst having an optically active ligand. The asymmetric hydrogenation of the 4-substituted NH-dihydroquinolines proceeded with moderate conversion rates (up to 62.6%) and enantioselectivity (up to 71.3% ee), whereas N-acetyl-dihydroquinolines gave even poorer conversion (up to 14%) and enantioselectivity (up to 31% ee).

In the light of the prior art described above, it is an object of the present invention to provide a process for preparing optically active 4-substituted 1,2,3,4-tetrahydroquinolines which process has advantages over the processes of the prior art. The process should allow the desired enantiomer to be prepared in high yield and high enantiomeric purity, with few process steps and few purification steps.

The object described above was achieved by a process for preparing a compound of the formula (a) or (b),

wherein

  • R1 is selected from the group consisting of C1-C6-alkyl, C1-C6-haloalkyl, C1-C6-alkoxy-C1-C6-alkyl, C3-C6-cycloalkyl, C6-C14-aryl, or C6-C14-aryl-C1-C4-alkyl,
    • wherein the C1-C6-alkyl, C3-C6-cycloalkyl and the C1-C6-alkoxy in the C1-C6-alkoxy-C1-C6-alkyl moiety, are optionally substituted by 1 to 3 substituents independently selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-haloalkyl, C1-C4-haloalkoxy and phenyl, wherein the phenyl may be substituted by one to five substituents selected independently from each other from halogen, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-haloalkyl, and C1-C4-haloalkoxy, and
    • wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy,
  • R2 and R3 are the same and are selected from the group consisting of hydrogen, C1-C6-alkyl, C1-C6-haloalkyl and C1-C6-alkoxy-C1-C6-alkyl, or
  • R2 and R3 together with the carbon to which they are bonded, form a C3-C6-cycloalkyl ring,
  • R4 is hydrogen, C1-C6-alkyl, C1-C6-haloalkyl, C1-C6-alkoxy, C1-C6-haloalkoxy, C1-C6-alkylamino, C2-C6-alkenyl, C2-C6-alkynyl, C3-C6-cycloalkyl, C3-C6-cycloalkyl-C1-C4-alkyl, C2-C6-alkenyloxy, 9-flurorenylmethyleneoxy, C6-C14-aryl, C6-C14-aryloxy, C6-C14-aryl-C1-C4-alkyloxy or C6-C14-aryl-C1-C4-alkyl,
    • wherein the C6-C14-aryl as such or as part of a composite substituent is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy,
  • n is 0, 1, 2, 3 or 4,
  • each substituent R5, if present, is independently selected from the group consisting of halogen, C1-C6-alkyl, C1-C6-haloalkyl, C1-C6-alkoxy, hydroxyl, amino and —C(═O)—C1-C6-alkyl,

comprising enantioselective hydrogenation of a compound of the formula (II)

wherein the substituents R1, R2, R3, R4, R5 and the integer n are each as defined for the compound of the formula (Ia) or (b),

in presence of a chiral iridium catalyst,

characterized in that the chiral iridium catalyst comprises a chiral ligand of the formula (IIIa), (IIIb), (IVa) or (IVb),

wherein

  • R6, R7 and R8 are independently from one another selected from the group consisting of hydrogen, halogen, C1-C6-alkyl, C1-C6-haloalkyl, C1-C6-alkoxy, C2-C6-alkenyl, C2-C6-alkynyl, C3-C7-cycloalkyl, C3-C7-cycloalkyl-C1-C4-alkyl, C6-C14-aryl and C6-C14-aryl-C1-C4-alkyl,
    • wherein the C1-C6-alkyl, C2-C6-alkenyl, C2-C6-alkynyl, C3-C7-cycloalkyl and the C3-C7-cycloalkyl in the C3-C7-cycloalkyl-C1-C4-alkyl moiety are optionally substituted by 1 to 3 substituents independently selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-alkoxy and C1-C4-haloalkyl and C1-C4-haloalkoxy, and
    • wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety are optionally substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy, C1-C4-haloalkoxy and phenyl, wherein the phenyl again is unsubstituted or substituted by one to five C1-C6-alkyl substituents,
  • R9 and R10 are independently from one another selected from the group consisting of C1-C6-alkyl, C2-C6-alkenyl, C2-C6-alkynyl, C1-C6-alkoxy, di(C1-C6-alkyl)amino, C3-C12-cycloalkyl, C3-C12-cycloalkyl-C1-C4-alkyl, C6-C14-aryl, C6-C14-aryloxy and C6-C14-aryl-C1-C4-alkyl,
    • wherein the C1-C6-alkyl, C2-C6-alkenyl, C2-C6-alkynyl, C1-C6-alkoxy and di(C1-C6-alkyl)amino, are optionally substituted by 1 to 3 substituents independently selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-haloalkyl, C1-C4-haloalkoxy and phenyl, wherein the phenyl may be substituted by one to five substituents selected independently from each other from halogen, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-haloalkyl, and C1-C4-haloalkoxy, and
    • wherein the C6-C14-aryl, C6-C14-aryloxy and C3-C12-cycloalkyl, in each case as such or as part of a composite substituent, are optionally substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy, C1-C4-haloalkoxy and phenyl, wherein the phenyl is unsubstituted or substituted by one to five C1-C6-alkyl substituents or
  • R9 and R10 together with the phosphorus atom to which they are bonded, form a phospholane ring, which may be substituted with one or two C1-C6-alkyl groups, or
  • R9 and R10 together form

    • where the bonds identified by “x” and “y” are both bonded directly to the phosphorus atom,
  • p and q are independently from one another selected from 0, 1 and 2,
  • R11 and R12 are independently selected from C1-C6-alkyl and phenyl, which may be substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-alkoxy and phenyl, which may be substituted by one or two C1-C4-alkyl substituents,
  • m is 1 or 2,
  • A is

    • where the bond identified by “*” is bonded directly to the phosphorus atom and where the bond identified by “#” is bonded directly to the oxazoline moiety,
  • R13 is C1-C6-alkyl, C1-C6-haloalkyl, C3-C12-cycloalkyl, C3-C12-cycloalkyl-C1-C4-alkyl, C1-C4-alkyl-C3-C7-cycloalkyl, C6-C14-aryl or C6-C14-aryl-C1-C4-alkyl,
    • wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy,
  • R14 and R15 are independently from one another selected from the group consisting of hydrogen, C1-C6-alkyl, C1-C6-haloalkyl, C3-C12-cycloalkyl, C3-C7-cycloalkyl-C1-C4-alkyl, C1-C4-alkyl-C3-C7-cycloalkyl, C6-C14-aryl and C6-C14-aryl-C1-C4-alkyl,
    • wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy, or
  • R14 and R15 together with the carbon to which they are bonded, form a C5-C6-cycloalkyl ring,
  • R16 and R17 are independently from one another selected from the group consisting of C1-C6-alkyl, C2-C6-alkenyl, C2-C6-alkynyl, C1-C6-alkoxy, di(C1-C6-alkyl)amino, C3-C12-cycloalkyl, C3-C12-cycloalkyl-C1-C4-alkyl, C6-C14-aryl, C6-C14-aryloxy and C6-C14-aryl-C1-C4-alkyl,
    • wherein the C1-C6-alkyl, C2-C6-alkenyl, C2-C6-alkynyl, C1-C6-alkoxy, C1-C6-cycloalkyl and di(C1-C6-alkyl)amino, are optionally substituted by 1 to 3 substituents independently selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-haloalkyl, C1-C4-haloalkoxy and phenyl, wherein the phenyl may be substituted by one to five substituents selected independently from each other from halogen, C1-C4-alkyl, phenyl, C1-C4-alkoxy, C1-C4-haloalkyl, and C1-C4-haloalkoxy, and
    • wherein the C6-C14-aryl, the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl, the C6-C14-aryloxy and C3-C12-cycloalkyl, in each case as such or as part of a composite substituent, are optionally substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, phenyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy, or
  • R16 and R17 together with the phosphorus atom to which they are bonded, form a phospholane ring, which may be substituted with one or two C1-C6-alkyl groups, or
  • R16 and R17 together form

    • where the bonds identified by “x” and “y” are both bonded directly to the phosphorus atom,
  • p and q are independently from one another selected from 0, 1 and 2, and
  • R11 and R12 are independently selected from C1-C6-alkyl and phenyl, which may be substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-alkoxy and phenyl, which may be substituted by one or two C1-C4-alkyl substituents.

It has been found, surprisingly, that optically active 4-substituted 1,2,3,4-tetrahydroquinolines (Ia and Ib) can be prepared in high yields and excellent enantioselectivity by enantioselective hydrogenation of the corresponding 4-substituted 1,2-dihydroquinolines (II) in presence of a chiral iridium (P,N)-ligand catalyst.

Definitions

In the definitions of the symbols given in the above formulae, collective terms were used, which are generally representative of the following substituents:

Halogen: fluorine, chlorine, bromine or iodine, preferably fluorine, chlorine or bromine, and more preferably fluorine or chlorine.

Alkyl: saturated, straight-chain or branched hydrocarbyl substituents having 1 to 6, preferably 1 to 4 carbon atoms, for example (but not limited to) C1-C6-alkyl such as methyl, ethyl, propyl (n-propyl), 1-methylethyl (iso-propyl), butyl (n-butyl), 1-methylpropyl (sec-butyl), 2-methylpropyl (iso-butyl), 1,1-dimethylethyl (tert-butyl), pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl and 1-ethyl-2-methylpropyl. Particularly, said group is a C1-C4-alkyl group, e.g. a methyl, ethyl, propyl, 1-methylethyl (isopropyl), butyl, 1-methylpropyl (sec-butyl), 2-methylpropyl (iso-butyl) or 1,1-dimethylethyl (tert-butyl) group. This definition also applies to alkyl as part of a composite substituent, for example C3-C6-cycloalkyl-C1-C4-alkyl, C6-C14-aryl-C1-C4-alkyl etc., unless defined elsewhere.

Alkenyl: unsaturated, straight-chain or branched hydrocarbyl substituents having 2 to 6, preferably 2 to 4 carbon atoms and one double bond in any position, for example (but not limited to) C2-C6-alkenyl such as vinyl, allyl, (E)-2-methylvinyl, (Z)-2-methylvinyl, isopropenyl, homoallyl, (E)-but-2-enyl, (Z)-but-2-enyl, (E)-but-1-enyl, (Z)-but-1-enyl, 2-methylprop-2-enyl, 1-methylprop-2-enyl, 2-methylprop-1-enyl, (E)-1-methylprop-1-enyl, (Z)-1-methylprop-1-enyl, pent-4-enyl, (E)-pent-3-enyl, (Z)-pent-3-enyl, (E)-pent-2-enyl, (Z)-pent-2-enyl, (E)-pent-1-enyl, (Z)-pent-1-enyl, 3-methylbut-3-enyl, 2-methylbut-3-enyl, 1-methylbut-3-enyl, 3-methylbut-2-enyl, (E)-2-methylbut-2-enyl, (Z)-2-methylbut-2-enyl, (E)-1-methylbut-2-enyl, (Z)-1-methylbut-2-enyl, (E)-3-methylbut-1-enyl, (Z)-3-methylbut-1-enyl, (E)-2-methylbut-1-enyl, (Z)-2-methylbut-1-enyl, (E)-1-methylbut-1-enyl, (Z)-1-methylbut-1-enyl, 1,1-dimethylprop-2-enyl, 1-ethylprop-1-enyl, 1-propylvinyl, 1-isopropylvinyl, (E)-3,3-dimethylprop-1-enyl, (Z)-3,3-dimethylprop-1-enyl, hex-5-enyl, (E)-hex-4-enyl, (Z)-hex-4-enyl, (E)-hex-3-enyl, (Z)-hex-3-enyl, (E)-hex-2-enyl, (Z)-hex-2-enyl, (E)-hex-1-enyl, (Z)-hex-1-enyl, 4-methylpent-4-enyl, 3-methylpent-4-enyl, 2-methylpent-4-enyl, 1-methylpent-4-enyl, 4-methylpent-3-enyl, (E)-3-methylpent-3-enyl, (Z)-3-methylpent-3-enyl, (E)-2-methylpent-3-enyl, (Z)-2-methylpent-3-enyl, (E)-1-methylpent-3-enyl, (Z)-1-methylpent-3-enyl, (E)-4-methylpent-2-enyl, (Z)-4-methylpent-2-enyl, (E)-3-methylpent-2-enyl, (Z)-3-methylpent-2-enyl, (E)-2-methylpent-2-enyl, (Z)-2-methylpent-2-enyl, (E)-1-methylpent-2-enyl, (Z)-1-methylpent-2-enyl, (E)-4-methylpent-1-enyl, (Z)-4-methylpent-1-enyl, (E)-3-methylpent-1-enyl, (Z)-3-methylpent-1-enyl, (E)-2-methylpent-1-enyl, (Z)-2-methylpent-1-enyl, (E)-1-methylpent-1-enyl, (Z)-1-methylpent-1-enyl, 3-ethylbut-3-enyl, 2-ethylbut-3-enyl, 1-ethylbut-3-enyl, (E)-3-ethylbut-2-enyl, (Z)-3-ethylbut-2-enyl, (E)-2-ethylbut-2-enyl, (Z)-2-ethylbut-2-enyl, (E)-1-ethylbut-2-enyl, (Z)-1-ethylbut-2-enyl, (E)-3-ethylbut-1-enyl, (Z)-3-ethylbut-1-enyl, 2-ethylbut-1-enyl, (E)-1-ethylbut-1-enyl, (Z)-1-ethylbut-1-enyl, 2-propylprop-2-enyl, 1-propylprop-2-enyl, 2-isopropylprop-2-enyl, 1-isopropylprop-2-enyl, (E)-2-propylprop-1-enyl, (Z)-2-propylprop-1-enyl, (E)-1-propylprop-1-enyl, (Z)-1-propylprop-1-enyl, (E)-2-isopropylprop-1-enyl, (Z)-2-isopropylprop-1-enyl, (E)-1-isopropylprop-1-enyl, (Z)-1-isopropylprop-1-enyl, 1-(1,1-dimethylethyl)ethenyl, buta-1,3-dienyl, penta-1,4-dienyl, hexa-1,5-dienyl or methylhexadienyl. Particularly, said group is vinyl or allyl. This definition also applies to alkenyl as part of a composite substituent unless defined elsewhere.

Alkynyl: straight-chain or branched hydrocarbyl substituents having 2 to 8, preferably 2 to 6, and more preferably 2 to 4 carbon atoms and one triple bond in any position, for example (but not limited to) C2-C6-alkynyl, such as ethynyl, prop-1-ynyl, prop-2-ynyl, but-1-ynyl, but-2-ynyl, but-3-ynyl, 1-methylprop-2-ynyl, pent-1-ynyl, pent-2-ynyl, pent-3-ynyl, pent-4-ynyl, 2-methylbut-3-ynyl, 1-methylbut-3-ynyl, 1-methylbut-2-ynyl, 3-methylbut-1-ynyl, 1-ethylprop-2-ynyl, hex-1-ynyl, hex-2-ynyl, hex-3-ynyl, hex-4-ynyl, hex-5-ynyl, 3-methylpent-4-ynyl, 2-methylpent-4-ynyl, 1-methylpent-4-ynyl, 2-methylpent-3-ynyl, 1-methylpent-3-ynyl, 4-methylpent-2-ynyl, 1-methylpent-2-ynyl, 4-methylpent-1-ynyl, 3-methylpent-1-ynyl, 2-ethylbut-3-ynyl, 1-ethylbut-3-ynyl, 1-ethylbut-2-ynyl, 1-propylprop-2-ynyl, 1-isopropylprop-2-ynyl, 2,2-dimethylbut-3-ynyl, 1,1-dimethylbut-3-ynyl, 1,1-dimethylbut-2-ynyl, or 3,3-dimethylbut-1-ynyl group. Particularly, said alkynyl group is ethynyl, prop-1-ynyl, or prop-2-ynyl. This definition also applies to alkynyl as part of a composite substituent unless defined elsewhere.

Alkylamino: monoalkylamino or dialkylamino, wherein monoalkylamino represents an amino radical having one alkyl residue with 1 to 4 carbon atoms attached to the nitrogen atom. Non-limiting examples include methylamino, ethylamino, n-propylamino, isopropylamino, n-butylamino and tert-butylamino. Wherein dialkylamino represents an amino radical having two independently selected alkyl residues with 1 to 4 carbon atoms each attached to the nitrogen atom. Non-limiting examples include N,N-dimethylamino, N,N-diethylamino, N,N-diisopropylamino, N-ethyl-N-methylamino, N-methyl-N-n-propylamino, N-iso-propyl-N-n-propylamino and N-tert-butyl-N-methylamino.

Alkoxy: saturated, straight-chain or branched alkoxy substituents having 1 to 6, more preferably 1 to 4 carbon atoms, for example (but not limited to) C1-C6-alkoxy such as methoxy, ethoxy, propoxy, 1-methylethoxy, butoxy, 1-methylpropoxy, 2-methylpropoxy, 1,1-dimethylethoxy, pentoxy, 1-methylbutoxy, 2-methylbutoxy, 3-methylbutoxy, 2,2-dimethylpropoxy, 1-ethylpropoxy, 1,1-dimethylpropoxy, 1,2-dimethylpropoxy, hexoxy, 1-methylpentoxy, 2-methylpentoxy, 3-methylpentoxy, 4-methylpentoxy, 1,1-dimethylbutoxy, 1,2-dimethylbutoxy, 1,3-dimethylbutoxy, 2,2-dimethylbutoxy, 2,3-dimethylbutoxy, 3,3-dimethylbutoxy, 1-ethylbutoxy, 2-ethylbutoxy, 1,1,2-trimethylpropoxy, 1,2,2-trimethylpropoxy, 1-ethyl-1-methylpropoxy and 1-ethyl-2-methylpropoxy. This definition also applies to alkoxy as part of a composite substituent unless defined elsewhere.

Cycloalkyl: mono- or polycyclic, saturated hydrocarbyl substituents having 3 to 12, preferably 3 to 8 and more preferably 3 to 6 carbon ring members, for example (but not limited to) cyclopropyl, cyclopentyl, cyclohexyl and adamantyl. This definition also applies to cycloalkyl as part of a composite substituent, for example C3-C6-cycloalkyl-C1-C4-alkyl, unless defined elsewhere.

Haloalkyl: straight-chain or branched alkyl substituents having 1 to 6, preferably 1 to 4 carbon atoms (as specified above), where some or all of the hydrogen atoms in these groups are replaced by halogen atoms as specified above, for example (but not limited to) C1-C3-haloalkyl such as chloromethyl, bromomethyl, dichloromethyl, trichloromethyl, fluoromethyl, difluoromethyl, trifluoromethyl, chlorofluoromethyl, dichlorofluoromethyl, chlorodifluoromethyl, 1-chloroethyl, 1-bromoethyl, 1-fluoroethyl, 2-fluoroethyl, 2,2-difluoroethyl, 2,2,2-trifluoroethyl, 2-chloro-2-fluoroethyl, 2-chloro-2,2-difluoroethyl, 2,2-dichloro-2-fluoroethyl, 2,2,2-trichloroethyl, pentafluoroethyl and 1,1,1-trifluoroprop-2-yl. This definition also applies to haloalkyl as part of a composite substituent unless defined elsewhere.

Haloalkenyl and haloalkynyl are defined analogously to haloalkyl except that, instead of alkyl groups, alkenyl and alkynyl groups are present as part of the substituent.

Haloalkoxy: straight-chain or branched alkoxy substituents having 1 to 6, preferably 1 to 4 carbon atoms (as specified above), where some or all of the hydrogen atoms in these groups are replaced by halogen atoms as specified above, for example (but not limited to) C1-C3-haloalkoxy such as chloromethoxy, bromomethoxy, dichloromethoxy, trichloromethoxy, fluoromethoxy, difluoromethoxy, trifluoromethoxy, chlorofluoromethoxy, dichlorofluoromethoxy, chlorodifluoromethoxy, 1-chloroethoxy, 1-bromoethoxy, 1-fluoroethoxy, 2-fluoroethoxy, 2,2-difluoroethoxy, 2,2,2-trifluoroethoxy, 2-chloro-2-fluoroethoxy, 2-chloro-2,2-difluoroethoxy, 2,2-dichloro-2-fluoroethoxy, 2,2,2-trichloroethoxy, pentafluoroethoxy and 1,1,1-trifluoroprop-2-oxy. This definition also applies to haloalkoxy as part of a composite substituent, unless defined elsewhere.

Aryl: mono-, bi- or tricyclic aromatic or partially aromatic substituents having 6 to 14 carbon atoms, for example (but not limited to) phenyl, naphthyl, tetrahydronapthyl, indenyl and indanyl. The binding to the superordinate general structure can be carried out via any possible ring member of the aryl residue. Aryl is preferably selected from phenyl, 1-naphthyl, 2-naphthyl, 9-phenantryl und 9-antracenyl. Phenyl is particularly preferred.

The term “enantioselective” as used herein means that one of the two possible enantiomers of the hydrogenation product, namely the enantiomer of the formula (Ia) or the enantiomer of the formula (Ib), is preferably formed. The “enantiomeric excess” or “ee” indicates the degree of enantioselectivity:

ee = major enantiomer ( mol ) - minor enantiomer ( mol ) major enantiomer ( mol ) + minor enantiomer ( mol ) × 100

The major enantiomer can be controlled by the selection of the chiral ligand, for example by selecting the chiral ligand of the formula (IIIa) or the opposite enantiomer (the ligand of the formula (IIIb)), or respectively by selecting the chiral ligand of the formula (IVa) or the opposite enantiomer (the ligand of the formula (IVb)).

The process according to the invention is used for preparing the compound of the formula (a) or (b), preferably (Ia).

Preferred are compounds of the formula (Ia) or (Ib), in particular (Ia), wherein the substituents are defined as follows:

  • R1 is C1-C6-alkyl or C6-C14-aryl-C1-C4-alkyl,
    • wherein C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy
  • R2 and R3 are the same and are selected from C1-C4-alkyl,
  • R4 is C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy, C1-C4-haloalkoxy, phenyl or benzyl,
  • n is 0, 1 or 2,
  • each substituent R5, if present, is independently selected from the group consisting of halogen, C1-C6-alkyl and C1-C6-haloalkyl.

More preferred are compounds of the formula (Ia) or (Ib), in particular (Ia), wherein the substituents are defined as follows:

  • R1 is C1-C6-alkyl
  • R2 and R3 are the same and are selected from C1-C4-alkyl,
  • R4 is C1-C4-alkyl, C1-C4-haloalkyl, phenyl or benzyl,
  • n is 0, 1 or 2,
  • each substituent R5, if present, is independently selected from the group consisting of halogen and C1-C6-alkyl.

Even more preferred are compounds of the formula (Ia) or (Ib), in particular (Ia), wherein the substituents are defined as follows:

  • R1 is methyl, ethyl or n-propyl,
  • R2 and R3 are methyl,
  • R4 is C1-C4-alkyl,
  • n is 0, 1 or 2,
  • each substituent R5, if present, is independently selected from the group consisting of halogen and C1-C6-alkyl.

Most preferred are compounds of the formula (Ia) or (Ib), in particular (Ia), wherein the substituents are defined as follows:

  • R1 is methyl or n-propyl,
  • R2 and R3 are methyl,
  • R4 is methyl,
  • n is 0 or 1,
    • substituent R5, if present, is fluorine.

The process according to the invention comprises enantioselective hydrogenation of the compound of the formula (II). The substituents R1, R2, R3, R4, R5 and the integer n in the compound of the formula (II) are each as defined for the compound of the formula (Ia) or (b).

The enantioselective hydrogenation of the compound of the formula (II) is conducted in presence of a chiral iridium catalyst comprising a chiral ligand of the formula (IIIa), (IIIb), (IVa) or (IVb).

In a preferred embodiment of the process according to the invention, the substituents of formulae (Ia), (Ib), (II), (IIIa), (IIIb), (IVa), (IVb) are defined as follows:

  • R1 is C1-C6-alkyl or C6-C14-aryl-C1-C4-alkyl,
    • wherein C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy
  • R2 and R3 are the same and are selected from C1-C4-alkyl,
  • R4 is C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy, C1-C4-haloalkoxy, phenyl or benzyl,
  • n is 0, 1 or 2,
  • each substituent R5, if present, is independently selected from the group consisting of halogen, C1-C6-alkyl and C1-C6-haloalkyl,
  • R6 is C1-C6-alkyl, C1-C6-haloalkyl, C3-C7-cycloalkyl or C6-C14-aryl,
    • wherein the C6-C14-aryl is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy, C1-C4-haloalkoxy and phenyl, wherein the phenyl again is unsubstituted or substituted by one to five C1-C6-alkyl substituents,
  • R7 and R8 are independently from one another hydrogen selected from the group consisting of hydrogen, C1-C6-alkyl, C6-C14-aryl, C1-C6-alkoxy or C1-C6-haloalkyl,
    • wherein the C6-C14-aryl is unsubstituted or substituted by one to five C1-C4-alkyl substituents,
  • R9 and R10 are independently from one another selected from the group consisting of C1-C6-alkyl, C1-C6-alkoxy, di(C1-C6-alkyl)amino, C3-C12-cycloalkyl, C6-C14-aryl, C6-C14-aryloxy and C6-C14-aryl-C1-C4-alkyl,
    • wherein the C1-C6-alkyl, C1-C6-alkoxy and di(C1-C6-alkyl)amino moieties are optionally substituted by 1 to 3 substituents independently selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-haloalkyl, C1-C4-haloalkoxy and phenyl, wherein the phenyl may be substituted by one to five substituents selected independently from each other from halogen, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-haloalkyl, and C1-C4-haloalkoxy, and
    • wherein the C6-C14-aryl, C6-C14-aryloxy and C3-C12-cycloalkyl, as such or as part of a composite substituent, in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy, C1-C4-haloalkoxy and phenyl, wherein the phenyl is unsubstituted or substituted by one to five C1-C6-alkyl substituents or
  • R9 and R10 together with the phosphorus atom to which they are bonded, form a phospholane ring, which may be substituted with one or two C1-C6-alkyl groups,
  • m is 1 or 2,
  • A is

    • where the bond identified by “*” is bonded directly to the phosphorus atom and where the bond identified by “#” is bonded directly to the oxazoline moiety,
  • R13 is C3-C6-alkyl, C3-C12-cycloalkyl, C6-C14-aryl or C6-C14-aryl-C1-C4-alkyl,
    • wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy,
  • R14 and R15 are independently from one another selected from the group consisting of C1-C6-alkyl, C3-C12-cycloalkyl, C6-C14-aryl and C6-C14-aryl-C1-C4-alkyl,
    • wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy, or
  • R14 and R15 together with the carbon to which they are bonded, form a C5-C6-cycloalkyl ring,
  • R16 and R17 are independently from one another selected from the group consisting of C1-C6-alkyl, C3-C12-cycloalkyl, C6-C14-aryl and C6-C14-aryl-C1-C4-alkyl,
    • wherein the C1-C6-alkyl is optionally substituted by 1 to 3 substituents independently selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-haloalkyl, C1-C4-haloalkoxy and phenyl, wherein the phenyl may be substituted by one to five substituents selected independently from each other from halogen, C1-C4-alkyl, phenyl, C1-C4-alkoxy, C1-C4-haloalkyl, and C1-C4-haloalkoxy, and
    • wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy, or
  • R16 and R17 together with the phosphorus atom to which they are bonded, form a phospholane ring, which may be substituted with one or two C1-C6-alkyl groups.

In a more preferred embodiment of the process according to the invention, the substituents of formulae (Ia), (Ib), (II), (IIIa), (IIIb), (IVa), (IVb) are defined as follows:

  • R1 is C1-C6-alkyl,
  • R2 and R3 are the same and are selected from C1-C4-alkyl,
  • R4 is C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy, C1-C4-haloalkoxy, phenyl or benzyl,
  • n is 0, 1 or 2,
    • each substituent R5, if present, is independently selected from the group consisting of halogen, C1-C6-alkyl and C1-C6-haloalkyl,
  • R6 is selected from the group consisting of 1-naphtyl, 2-naphtyl, 9-antracenyl, 9-phenantryl or phenyl, which is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-alkyl, C1-C4-haloalkyl and phenyl,
    • wherein the phenyl again is unsubstituted or substituted by one to five C1-C6-alkyl substituents,
  • R7 and R8 are independently from one another hydrogen or C1-C6-alkyl,
  • R9 and R10 are independently from one another selected from the group consisting of ethyl, iso-propyl, sec-butyl, iso-butyl, tert-butyl, cyclohexyl, cyclopentyl, adamantyl and benzyl, and
  • m is 1 or 2,
  • A is

    • where the bond identified by “*” is bonded directly to the phosphorus atom and where the bond identified by “#” is bonded directly to the oxazoline moiety,
  • R13 is selected from the group consisting of C3-C6-alkyl, C3-C12-cycloalkyl, C6-C14-aryl or C6-C14-aryl-C1-C4-alkyl,
    • wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen or C1-C4-alkyl,
  • R14 and R15 are independently from one another selected from the group consisting of C1-C6-alkyl and C6-aryl-C1-C4-alkyl,
    • wherein the C6-aryl in the C6-C14-aryl-C1-C4-alkyl moiety is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen and C1-C4-alkyl,
  • R14 and R15 together with the carbon to which they are bonded, form a C5-C6-cycloalkyl ring,
  • R16 and R17 are independently from one another selected from the group consisting of C1-C6-alkyl, C3-C12-cycloalkyl, C6-C14-aryl and C6-C14-aryl-C1-C4-alkyl,
    • wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, phenyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy, or
  • R16 and R17 together with the phosphorus atom to which they are bonded, form a phospholane ring, which may be substituted with one or two C1-C6-alkyl groups.

In the most preferred embodiment of the process according to the invention, the substituents of formulae (Ia), (Ib), (II), (IIIa), (IIIb), (IVa), (IVb) are defined as follows:

  • R1 is C1-C4-alkyl,
  • R2 and R3 are methyl,
  • R4 is C1-C4-alkyl,
  • n is 0 or 1
  • R5 if present, is fluorine,
  • R6 phenyl, 2,6- or 3,5-dimethylphenyl, 2,4,6-trimethylphenyl, 4-tert-butylphenyl, 4-methoxyphenyl, 3,5-bis-tert-butyl-4-methoxyphenyl, 4-tert-butyl-2,6-dimethylphenyl, 4-fluorophenyl, 4-trifluoromethylphenyl, 1-naphtyl, 9-antracenyl 2,4,6-triisopropylphenyl, 9-phenantryl or 2,6-diethyl-4-methylphenyl,
  • R7 is hydrogen,
  • R8 is hydrogen or methyl,
  • R9 and R10 are each the same and selected from the group consisting of ethyl, iso-propyl, tert-butyl, cyclopentyl, adamantyl and cyclohexyl,
  • m is 1 or 2,
  • A is

    • where the bond identified by “*” is bonded directly to the phosphorus atom and where the bond identified by “#” is bonded directly to the oxazoline moiety,
  • R13 is tert-butyl, iso-propyl or phenyl,
  • R14 and R15 are methyl,
  • R16 and R17 are each the same and 2-methylphenyl or 3,5-bismethylphenyl.

In a preferred embodiment of the process according to the invention, the ligand of the formula (IIIa) or (IIIb) is used. Depending on whether compound (Ia) or (Ib) is the desired product, the ligand of the formula (IIIa) or (IIIb) is selected.

Preferred are ligands of the formulae (IIIa) and (IIIb), wherein the substituents are defined as follows:

  • R6 is C1-C6-alkyl, C1-C6-haloalkyl, C3-C7-cycloalkyl or C6-C14-aryl,
    • wherein the C6-C14-aryl is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy, C1-C4-haloalkoxy and phenyl, wherein the phenyl again is unsubstituted or substituted by one to five C1-C6-alkyl substituents,
  • R7 and R8 are independently from one another selected from the group consisting of hydrogen, C1-C6-alkyl, C1-C6-alkoxy, C6-C14-aryl or C1-C6-haloalkyl,
    • wherein the C6-C14-aryl is unsubstituted or substituted by one to five C1-C4-alkyl substituents,
  • R9 and R10 are independently from one another selected from the group consisting of C1-C6-alkyl, C1-C6-alkoxy, di(C1-C6-alkyl)amino, C3-C12-cycloalkyl, C6-C14-aryl, C6-C14-aryloxy and C6-C14-aryl-C1-C4-alkyl,
    • wherein the C1-C6-alkyl, C1-C6-alkoxy and di(C1-C6-alkyl)amino moieties are optionally substituted by 1 to 3 substituents independently selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-haloalkyl, C1-C4-haloalkoxy and phenyl, wherein the phenyl may be substituted by one to five substituents selected independently from each other from halogen, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-haloalkyl, and C1-C4-haloalkoxy, and
    • wherein the C6-C14-aryloxy, C3-C12-cycloalkyl and C6-C14-aryl, as such or as part of a composite substituent, in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy, C1-C4-haloalkoxy and phenyl, wherein the phenyl is unsubstituted or substituted by one to five C1-C6-alkyl substituents or
  • R9 and R10 together with the phosphorus atom to which they are bonded, form a phospholane ring, which may be substituted with one or two C1-C6-alkyl groups, and
  • m is 1 or 2.

More preferred are ligands of the formulae (IIIa) and (IIIb), wherein the substituents are defined as follows:

  • R6 is selected from the group consisting of 1-naphtyl, 2-naphtyl, 9-antracenyl, 9-phenantryl or phenyl, which is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-alkyl, C1-C4-haloalkyl and phenyl, wherein the phenyl again is unsubstituted or substituted by one to five C1-C6-alkyl substituents,
  • R7 and R8 are independently from one another hydrogen or C1-C6-alkyl,
  • R9 and R10 are independently from one another selected from the group consisting of ethyl, iso-propyl, sec-butyl, iso-butyl, tert-butyl, cyclohexyl, cyclopentyl, adamantyl and benzyl, and
  • m is 1 or 2.

Most preferred are ligands of the formulae (IIIa) and (IIIb), wherein the substituents are defined as follows:

  • R6 is selected from the group consisting of, phenyl, 2,6- or 3,5-dimethylphenyl, 2,4,6-trimethylphenyl, 4-tert-butylphenyl, 4-methoxyphenyl, 3,5-bis-tert-butyl-4-methoxyphenyl, 4-tert-butyl-2,6-dimethylphenyl, 4-fluorophenyl, 4-trifluoromethylphenyl, 1-naphtyl, 9-antracenyl 2,4,6-triisopropylphenyl, 9-phenantryl or 2,6-diethyl-4-methylphenyl,
  • R7 is hydrogen
  • R8 is hydrogen or methyl,
  • R9 and R10 are each the same and tert-butyl, cyclopentyl or cyclohexyl, and
  • m is 1.

In another preferred embodiment of the process according to the invention, the ligand of the formula (IVa) or (IVb) is used. Depending on whether compound (Ia) or (Ib) is the desired product, the ligand of the formula (IVa) or (IVb) is selected.

Preferred are ligands of the formulae (IVa) and (IVb), wherein the substituents are defined as follows:

  • A is

    • where the bond identified by “*” is bonded directly to the phosphorus atom and where the bond identified by “#” is bonded directly to the oxazoline moiety,
  • R13 is C3-C6-alkyl, C3-C12-cycloalkyl, C6-C14-aryl or C6-C14-aryl-C1-C4-alkyl,
    • wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy,
  • R14 and R15 are independently from one another selected from the group consisting of C1-C6-alkyl, C6-C14-aryl, C3-C12-cycloalkyl, and C6-C14-aryl-C1-C4-alkyl,
    • wherein C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy, or
  • R14 and R15 together with the carbon to which they are bonded, form a C5-C6-cycloalkyl ring,
  • R16 and R17 are independently from one another selected from the group consisting of C1-C6-alkyl, C3-C12-cycloalkyl, C6-C14-aryl and C6-C14-aryl-C1-C4-alkyl,
    • wherein the C1-C6-alkyl is optionally substituted by 1 to 3 substituents independently selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-haloalkyl, C1-C4-haloalkoxy and phenyl, wherein the phenyl may be substituted by one to five substituents selected independently from each other from halogen, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-haloalkyl, and C1-C4-haloalkoxy, and
    • wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, phenyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy, or
  • R16 and R17 together with the phosphorus atom to which they are bonded, form a phospholane ring, which may be substituted with one or two C1-C6-alkyl groups.

More preferred are ligands of the formulae (IVa) and (IVb), wherein the substituents are defined as follows:

  • A is

    • where the bond identified by “*” is bonded directly to the phosphorus atom and where the bond identified by “#” is bonded directly to the oxazoline moiety,
  • R13 is iso-propyl, sec-butyl, iso-butyl, tert-butyl, phenyl or benzyl,
  • R14 and R15 are independently from one another selected from the group consisting of C1-C6-alkyl, and C6-aryl-C1-C4-alkyl,
    • wherein the C6-aryl in the C6-C14-aryl-C1-C4-alkyl moiety is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen and C1-C4-alkyl,
  • R16 and R17 are independently from one another phenyl, 1-naphthyl or 2-naphthyl, which in each case is unsubstituted or substituted by one to five C1-C4-alkyl substituents

Most preferred are ligands of the formulae (IVa) and (IVb), wherein the substituents are defined as follows:

  • A is

    • where the bond identified by “*” is bonded directly to the phosphorus atom and where the bond identified by “#” is bonded directly to the oxazoline moiety,
  • R13 is tert-butyl,
  • R14 and R15 are methyl, and
  • R16 and R17 are independently from one another phenyl, which is substituted by one or two methyl, in particular R16 and R17 are each the same and phenyl, which is substituted by one or two methyl or R16 and R17 are each the same and 2-methylphenyl or 3,5-dimethylphenyl.

Preferably, the chiral iridium catalyst is selected from the group consisting of [IrL*(COD)]Y and [IrL*(nbd)]Y, wherein

  • L* is the chiral ligand of the formula (IIIa), (IIIb), (IVa) or (IVb),
  • COD represents 1,5-cyclooctadiene,
  • nbd represents norbornadiene, and
  • Y is a non-coordinating anion selected from the group consisting of [B(R18)4]−, PF6−, SbF6−, CF3SO3−, [Al{OC(CF3)3}4]− (VII) and Δ-TRISPHAT (VIII)

    • wherein R18 is selected from fluorine and phenyl, which is unsubstituted or substituted with one to five substituents selected from C1-C4-alkyl, C1-C4-haloalkyl and halogen.

More preferred are chiral iridium catalysts of the formulae [IrL*(COD)]Y and [IrL*(nbd)]Y, wherein Y is [Al{OC(CF3)3}4]− (VII) or [B(R18)4]−, wherein R18 is phenyl, which is unsubstituted or substituted with one to five substituents selected from fluorine and trifluoromethyl.

Even more preferred are chiral iridium catalysts of the general formulae (Va), (Vb), (VIa) and (VIb)

wherein

  • R6 is selected from the group consisting of 1-naphtyl, 2-naphtyl, 9-antracenyl, 9-phenantryl or phenyl,
    • wherein 1-naphtyl, 2-naphtyl, 9-antracenyl, 9-phenantryl and phenyl are unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-alkyl, C1-C4-haloalkyl and phenyl, wherein the phenyl again is unsubstituted or substituted by one to five C1-C6-alkyl substituents,
  • R7 and R8 are independently from one another hydrogen, C1-C6-alkyl or C1-C6-alkoxy
  • R9 and R10 are independently from one another selected from the group consisting of ethyl, iso-propyl, sec-butyl, iso-butyl, tert-butyl, cyclohexyl, cyclopentyl, adamantyl and benzyl,
  • m is 1 or 2,
  • R13 is iso-propyl, sec-butyl, iso-butyl, tert-butyl, phenyl or benzyl,
  • R14 and R15 are independently from one another selected from the group consisting of C1-C6-alkyl, and C6-aryl-C1-C4-alkyl,
    • wherein the C6-aryl in the C6-C14-aryl-C1-C4-alkyl moiety is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen and C1-C4-alkyl,
  • R16 and R17 are independently from one another phenyl, 1-naphthyl or 2-naphthyl, which in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl and C1-C4-haloalkyl, and
  • R18 is phenyl, which is unsubstituted or substituted with one to five substituents selected from fluorine and C1-C4-haloalkyl.

Particularly preferred are chiral iridium catalysts of the general formulae (Va), (Vb), (VIa) and (VIb), wherein

  • R6 is selected from the group consisting of phenyl, 2,6- or 3,5-dimethylphenyl, 2,4,6-trimethylphenyl, 4-tert-butylphenyl, 4-methoxyphenyl, 3,5-bis-tert-butyl-4-methoxyphenyl, 4-tert-butyl-2,6-dimethylphenyl, 4-fluorophenyl, 4-trifluoromethylphenyl, 1-naphtyl, 9-antracenyl, 2,4,6-triisopropylphenyl, 9-phenantryl and 2,6-diethyl-4-methylphenyl,
  • R7 is hydrogen,
  • R8 is hydrogen or methyl
  • R9 and R10 are each the same and tert-butyl, adamantly, cyclopentyl or cyclohexyl,
  • m is 1 or 2,
  • R13 is tert-butyl,
  • R14 and R15 are methyl,
  • R16 and R17 are independently from one another phenyl, which is substituted by one or two methyl, in particular R16 and R17 are each the same and 2-methylphenyl or 3,5-dimethylphenyl, and
  • R18 is 3,5-bis(trifluoromethyl)phenyl.

In an alternative embodiment the chiral iridium catalysts is of the general formulae (Va) and (Vb), wherein

  • R6 is selected from the group consisting of phenyl, 2,6- or 3,5-dimethylphenyl, 2,4,6-trimethylphenyl, 4-tert-butylphenyl, 4-methoxyphenyl, 3,5-bis-tert-butyl-4-methoxyphenyl, 4-tert-butyl-2,6-dimethylphenyl, 4-fluorophenyl, 4-trifluoromethylphenyl, 1-naphtyl, 9-antracenyl, 2,4,6-triisopropylphenyl, 9-phenantryl and 2,6-diethyl-4-methylphenyl,
  • R7 is hydrogen
  • R8 is C1-C6-alkoxy
  • R9 and R10 are independently from one another selected from the group consisting of ethyl, iso-propyl, sec-butyl, iso-butyl, tert-butyl, cyclohexyl, cyclopentyl, adamantyl and benzyl, and
  • m is 1.

The amount of iridium catalyst used is preferably within the range of from 0.001 mol % to 5 mol %, more preferably 0.005 mol % to 4 mol %, most preferably 0.01 mol % to 3 mol %, in particular 0.01 mol % to 2.0 mol %, based on the amount of the compound of the formula (II).

The chiral iridium catalyst may be prepared by methods known in the art from an iridium (I) catalyst precursor, such as [Ir(COD)Cl]2, the chiral ligand of the formula (IIIa), (IIIb), (IVa) or (IVb) and an alkali salt of the non-coordinating anion (S. Kaiser et al., Angew. Chem. Int. Ed. 2006, 45, 5194-5197; W. J. Drury III et al., Angew. Chem. Int. Ed. 2004, 43, 70-74).

The process according to the invention comprises enantioselective hydrogenation of the compound of the formula (II).

Preferably, the hydrogenation is conducted using hydrogen gas at a pressure of from 1 to 300 bar, preferably 3 to 200 bar, most preferably 20 to 150 bar.

The hydrogenation is preferably conducted at a temperature within the range of from 20° C. to 130° C., more preferably 30° C. to 100° C.

Suitable solvents are halogenated alcohols such as 2,2,2,-trifluoroethanol, hexafluoroisopropanol (1,1,1,3,3,3-hexafluoro-2-propanol) and tetrafluoropropanol (2,2,3,3-tetrafluoro-1-propanol), halogenated hydrocarbons, such as chlorobenzene, dichlorobenzene, dichloromethane, chloroform, tetrachloromethane, dichloroethane and trichloroethane, aromatic hydrocarbons such as benzene, toluene and xylene, ethers such as diethyl ether, diisopropyl ether, methyl tert-butyl ether, methyl tert-amyl ether, dioxane, tetrahydrofuran, 1,2-dimethoxyethane, 1,2-diethoxyethane and anisole, and esters such as ethyl acetate, isopropyl acetate, and mixtures thereof.

Preferred solvents are selected from the group consisting of 2,2,2,-trifluoroethanol, hexafluoroisopropanol, 1,2-dichloroethane, tetrafluoropropanol, 1,4-dioxane, isopropyl acetate, toluene, and mixtures thereof.

More preferred solvents are selected from the group consisting of 2,2,2,-trifluoroethanol, hexafluoroisopropanol, 1,2-dichloroethane, tetrafluoropropanol, and mixtures thereof.

Especially preferred are 2,2,2,-trifluoroethanol and hexafluoroisopropanol.

Most preferred is hexafluoroisopropanol.

The hydrogenation may optionally be conducted in presence of an acidic additive, such as acetic acid, trifluoroacetic acid, camphorsulfonic acid, p-toluenesulfonic acid, pivalic acid, benzoic acid, formic acid, butyric acid or oxalic acid. If an acidic additive is used, it is preferably used as a mixture with the solvent.

The amount of acidic used is preferably at most 20 mol %, more preferably at most 10 mol %, and in particular within the range of from 0 to 5 mol %, based on the amount of the compound of the formula (II).

Preparation of Iridium Catalysts

The ligand precursors (enantiomerically enriched secondary alcohols) were prepared according to known literature procedures like to the method disclosed in S. Kaiser et al., Angew. Chem. Int. Ed. 2006, 45, 5194-5197 or in D. H. Woodmansee Chem. Sci 2010, 1, 72. The ligands and Iridium complexes were prepared by a modified procedure based on the same literature precedents:

Procedure of ligand synthesis (under Ar): A solution of alcohol precursor in THE (0.25 mmol, in 5.0 mL THF) was cooled to −78° C. and n-BuLi (0.1 mL of a 2.5 M n-BuLi solution in hexane; 0.25 mmol; 1 eq.) was added dropwise to the continuously stirred solution. After completion of the addition the solution was allowed to warm to room temperature and was stirred at this temperature for further 30 min. The solution was cooled to −78° C. again and R2PCl (0.25 mmol, 1 eq.) was added to the continuously stirred solution. The mixture was allowed to warm to room temperature and subsequently heated to 50° C. and kept at this temperature overnight. The theoretical yield of ligand was calculated using 31P-NMR and the ligand was used for the next step without further purification.

Procedure of complexation (under Ar): To the crude ligand solution was added [Ir(COD)2]BARF (BARF=Tetrakis[3,5-bis(trifluoromethyl)phenyl]-borate) (as a solid, 1 eq. based on the theoretical yield). The resulting mixture was heated to 50° C. and kept at this temperature for 3 h.

Work-up (under air): After cooling to room temperature the reaction solution is rotary evaporated onto silica, loaded onto a column of silica. Side components were eluted using pentane/diethylether and the desired complexes subsequently with DCM. The solvent was then evaporated under reduced pressure.

The following specified catalysts were synthesized and characterized:

with m=1 and R18=3,5-bis(trifluoromethyl)phenyl

Catalyst R6 R7 R8 R9, R10 Va-1 phenyl H H tert-butyl Va-2 phenyl H methyl tert-butyl Vb-3 phenyl H H cyclohexyl Va-4 phenyl H methyl cyclohexyl Vb-5 4-tert-butylphenyl H H cyclohexyl Va-6 4-tert-butylphenyl H methyl cyclohexyl Vb-7 9-antracenyl H H cyclohexyl Va-8 9-antracenyl H methyl cyclohexyl Va-9 2,6-dimethylphenyl H methyl cyclohexyl Va-10 2,4,6-trimethylphenyl H methyl cyclohexyl Va-11 3,5-dimethylphenyl H methyl cyclohexyl Va-12 1-naphtyl H methyl cyclohexyl Va-13 4-methoxyphenyl H methyl tert-butyl Va-14 4-fluorophenyl H methyl tert-butyl Va-15 4-(trifluoromethyl)phenyl H methyl tert-butyl Va-16 phenyl H methyl cyclopentyl Vb-17 phenyl H H ethyl Va-18 phenyl H methyl isopropyl Va-19 methyl H methyl cyclohexyl Va-20 3,5-bis-tert.-butyl,-4- H methyl cyclohexyl methoxyphenyl Va-21 2,4,6-triisopropylphenyl H methyl cyclohexyl Va-22 4-tert-butyl-2,6- H methyl cyclohexyl dimethylphenyl Va-23 phenyl H H adamantyl

Va-2

The reaction was performed according to the above described procedure. The complex could be isolated as an orange solid (89.5 mg; 53% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CD2Cl2): δ (ppm)=8.26 (dd, J=7.9, 1.7 Hz, 2H), 7.81-7.36 (in, 16H), 5.75 (dt, J=8.0, 5.2 Hz, 1H), 5.34-5.29 (in, 1H), 4.51 (q, J=5.3, 3.2 Hz, 1H), 4.11 (dq, J=12.5, 7.6, 5.9 Hz, 1), 3.08 (ddd, J=16.6, 10.3, 3.8 Hz, 1H), 2.99-2.70 (i, 2H), 2.61-2.00 (m, 8H), 1.92-1.79 (i, 1H), 1.69 (dd, J=14.8, 8.1 Hz, 1H), 1.51 (s, 9H), 1.29-1.24 (i, 3H), 1.06 (d, J=14.4 Hz, 9H). 31P-NMR (122 MHz, CD2Cl2) δ (ppm)=142.09. 19F-NMR (282 MHz, CD2Cl2) δ (ppm)=−62.85. HR-MS (ESI) m/z calcd for C31H44NOPIr [M]+ 670.2790 found 670.2798.

Va-4

The reaction was performed according to the above described procedure. The complex could be isolated as an orange solid (241 mg; 71% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CD2Cl2): δ (ppm)=8.38-8.14 (m, 2H), 7.83-7.43 (m, 16H), 5.76 (dt, J=7.7, 4.9 Hz, 1H), 4.81 (t, J=7.6 Hz, 1H), 4.70-4.46 (m, 1H), 3.56-3.39 (m, 1H), 3.06 (ddd, J=16.7, 10.3, 3.6 Hz, 1H), 2.98-2.73 (m, 2H), 2.71-2.57 (m, 1H), 2.44 (s, 3H), 2.41-2.02 (m, 6H), 2.00-1.75 (m, 7H), 1.72-1.54 (m, 4H), 1.46-0.94 (m, 13H), 0.72-0.50 (m, 1H). 31P-NMR (122 MHz, CD2Cl2) δ (ppm)=121.27. 19F-NMR (282 MHz, CD2Cl2) δ (ppm)=−62.86. HR-MS (ESI) m/z calcd for C35H48NOPIr [M]+ 722.3103 found 722.3116.

Vb-5

The reaction was performed according to the above described procedure using 287 mg of [Ir(COD)2]BARF (0.225 mmol). The complex could be isolated as an orange solid (261 mg; 74% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CD2Cl2): δ (ppm)=8.25 (d, J=8.3 Hz, 2H), 7.87 (d, J=8.1 Hz, 1H), 7.81-7.64 (m, 111H), 7.56 (s, 4H), 5.74 (dt, J=8.2, 4.6 Hz, 1H), 4.95-4.74 (m, 1H), 4.74-4.51 (m, 1H), 3.60-3.45 (m, 1H), 3.23-2.91 (m, 2H), 2.90-2.70 (m, 1H), 2.67-2.50 (m, 1H), 2.52-2.23 (m, 4H), 2.28-2.04 (m, 3H), 2.04-1.77 (m, 7H), 1.69-1.58 (m, 4H), 1.45-1.26 (m, 17H), 1.17-0.95 (m, 4H), 0.68-0.42 (m, 1H). 31P-NMR (122 MHz, CD2Cl2) δ (ppm)=121.12. 19F-NMR (282 MHz, CD2Cl2) δ (ppm)=−62.85.

HR-MS (ESI) m/z calcd for C38H54NOPIr [M]+ 764.3572 found 764.3586.

Va-6

The reaction was performed according to the above described procedure. The complex could be isolated as an orange solid (286 mg; 64% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CDCl3): δ (ppm)=8.20 (d, J=8.2 Hz, 2H), 7.77-7.69 (m, 8H), 7.66 (d, J=8.4 Hz, 2H), 7.53 (d, J=4.9 Hz, 5H), 5.77-5.67 (m, 1H), 4.78 (d, J=7.6 Hz, 1H), 4.57 (s, 1H), 3.47 (s, 1H), 3.08-2.89 (m, 1H), 2.89-2.66 (m, 2H), 2.59 (p, J=7.4 Hz, 1H), 2.47-1.74 (m, 15H), 1.42 (s, 17H), 1.18-0.78 (m, 5H), 0.72-0.48 (m, 1H). 31P-NMR (122 MHz, CDCl3) 121.31. 19F-NMR (282 MHz, CDCl3) δ=−62.42. HR-MS (ESI): m/z calculated for [C39H56NOP193Ir]+: 778.3729 found 778.3732.

Vb-7

The reaction was performed according to the above described procedure using 287 mg of [Ir(COD)2]BARF (0.225 mmol). The complex could be isolated after two time purification as an orange solid (151 mg; 36% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CD2Cl2): δ (ppm)=8.84 (s, 1H), 8.38-8.27 (m, 1H), 8.21 (ddt, J=8.5, 1.3, 0.7 Hz, 1H), 8.18-8.02 (m, 2H), 7.83-7.72 (m, 10H), 7.72-7.54 (m, 6H), 7.49 (ddd, J=8.8, 6.6, 1.4 Hz, 1H), 7.23-6.96 (m, 1H), 5.74-5.54 (m, 1H), 5.26-5.12 (m, 1H), 4.41-4.18 (m, 1H), 3.53-3.15 (m, 3H), 2.75-2.61 (m, 2H), 2.59-2.32 (m, 2H), 2.18-1.91 (m, 6H), 1.92-1.74 (m, 5H), 1.74-1.56 (m, 2H), 1.48-1.21 (m, 10H), 1.18-0.99 (m, 1H), 0.96-0.59 (m, 2H), 0.39-0.15 (m, 1H), 0.06-0.11 (m, 1H). 31P-NMR (122 MHz, CD2Cl2) δ (ppm)=120.30. 19F-NMR (282 MHz, CD2Cl2) δ (ppm)=−62.87. HR-MS (ESI) m/z calcd for C42H50NOPIr [M]+ 808.3259 found 808.3278.

Va-8

The reaction was performed according to the above described procedure using 287 mg of [Ir(COD)2]BARF (0.225 mmol). The complex could be isolated using DCM (100%) to afford an orange solid (296 mg; 78% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CD2Cl2): δ (ppm)=8.68 (s, 1H), 8.23-7.85 (m, 3H), 7.75-7.23 (m, 17H), 7.05 (dq, J=8.8, 1.0 Hz, 1H), 5.61-5.40 (m, 2H), 5.12-4.88 (m, 1H), 4.24-4.00 (m, 1H), 3.25-2.88 (m, 3H), 2.58-2.46 (m, 2H), 2.44-2.14 (m, 7H), 2.08-1.61 (m, 111H), 1.61-1.37 (m, 5H), 1.37-1.07 (m, 6H), 1.03-0.85 (m, 1H), 0.65-0.45 (m, 1H), 0.16 (dtd, J=15.8, 10.4, 5.6 Hz, 1H), −0.16 (dt, J=13.2, 9.1 Hz, 1H). 31P-NMR (122 MHz, CD2Cl2) δ=120.57. 19F-NMR (282 MHz, CD2Cl2) δ=−62.86. HR-MS (ESI) m/z calcd for C43H52NOPIr [M]+ 822.3416 found 822.3416.

Va-9

The reaction was performed according to the above described procedure using 287 mg of [Ir(COD)2]BARF (0.225 mmol). The complex could be isolated as an orange solid (298 mg; 82% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CD2Cl2): δ (ppm)=7.80-7.52 (m, 12H), 7.42-7.19 (m, 3H), 7.12 (d, J=7.5 Hz, 1H), 5.65 (td, J=5.6, 2.6 Hz, 1H), 5.48-5.42 (m, 1H), 4.43-4.37 (m, 1H), 3.38-3.30 (m, 1H), 3.21-2.89 (m, 3H), 2.67 (s, 3H), 2.58-2.45 (m, 2H), 2.42 (s, 3H), 2.38-2.16 (m, 2H), 2.13-2.05 (m, 3H), 2.02-1.89 (m, 4H), 1.84 (s, 3H), 1.81-1.72 (m, 2H), 1.64-1.49 (m, 3H), 1.39-1.19 (m, 8H), 1.12-0.99 (m, 4H), 0.68-0.56 (m, 1H). 31P-NMR (122 MHz, CD2Cl2) δ=118.80. 19F-NMR (282 MHz, CD2Cl2) δ=−62.88. HR-MS (ESI) m/z calcd for CH52NOPIr [M]+ 750.3416 found 750.3420.

Va-10

The reaction was performed according to the above described procedure using 287 mg of [Ir(COD)2]BARF (0.225 mmol). The complex could be isolated as an orange solid (148 mg; 40% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CD2Cl2): δ (ppm)=7.91-7.46 (m, 12H), 7.21 (s, 1H), 7.09 (s, 1H), 6.94 (s, 1H), 5.67-5.63 (m, 1H), 5.46-5.41 (m, 1H), 4.38-4.36 (m, 1H), 3.36-3.32 (m, 1H), 3.19-2.85 (m, 3H), 2.64 (s, 3H), 2.53-2.46 (m, 2H), 2.41 (s, 3H), 2.35 (s, 3H), 2.31-2.18 (m, 2H), 2.19-1.83 (m, 14H), 1.68-1.54 (m, 6H), 1.38-1.20 (m, 5H), 1.14-0.97 (m, 5H), 0.68-0.56 (m, 1H). 31P-NMR (122 MHz, CD2Cl2) δ=118.64. 19F-NMR (282 MHz, CD2Cl2) δ=−62.87. HR-MS (ESI) m/z calcd for C38H54NOPIr [M]+ 764.3572 found 764.3577.

Va-11

The reaction was performed according to the above described procedure using 287 mg of [Ir(COD)2]BARF (0.225 mmol). The complex could be isolated using DCM (100%) to afford an orange solid (310 mg; 85% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CD2Cl2): δ (ppm)=7.86 (s, 2H), 7.79-7.47 (m, 13H), 7.36 (s, 1H), 5.79-5.62 (m, 1H), 4.78-4.74 (m, 1H), 4.57-4.53 (m, 1H), 3.56-3.48 (m, 1H), 3.13-2.95 (m, 1H), 2.95-2.61 (m, 3H), 2.51 (s, 6H), 2.47-2.36 (m, 5H), 2.34-2.03 (m, 5H), 2.03-1.77 (m, 7H), 1.71-1.47 (m, 7H), 1.45-1.19 (m, 5H), 1.19-0.98 (m, 4H), 0.70-0.62 (m, 1H). 31P-NMR (122 MHz, CD2Cl2) δ=121.65. 19F-NMR (282 MHz, CD2Cl2) δ=−62.88. HR-MS (ESI) m/z calcd for C37H52NOPIr [M]+ 750.3416 found 750.3406.

Va-12

The reaction was performed according to the above described procedure using 287 mg of [Ir(COD)2]BARF (0.225 mmol). The complex could be isolated as an orange solid (286 mg; 78% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CD2Cl2): δ (ppm)=8.61-8.48 (m, 1H), 8.28-8.15 (m, 1H), 8.11-7.98 (m, 1H), 7.98-7.81 (m, 1H), 7.79-7.50 (m, 16H), 5.70 (ddd, J=8.1, 4.9, 3.2 Hz, 1H), 5.37-5.25 (m, 1H), 4.79 (d, J=10.4 Hz, 1H), 3.53-3.41 (m, 1H), 3.13 (ddd, J=17.2, 9.5, 4.9 Hz, 1H), 2.96 (ddd, J=17.1, 9.4, 4.9 Hz, 1H), 2.88-2.66 (m, 1H), 2.49-2.34 (m, 7H), 2.27-2.14 (m, 1H), 2.09-1.56 (m, 15H), 1.43-1.12 (m, 9H), 1.06-0.92 (m, 1H), 0.78-0.59 (m, 1H), 0.42-0.25 (m, 1H). 31P-NMR (122 MHz, CD2Cl2) δ=121.69. 19F-NMR (282 MHz, CD2Cl2) δ=−62.87. HR-MS (ESI) m/z calcd for C39H50NOPIr [M]+ 722.3259 found 722.3262.

Va-13

The reaction was performed according to the above described procedure. The theoretical yield of the ligand was 51%. The complex could be isolated as an orange solid (78.0 mg; 39% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CDCl3): δ (ppm)=8.22 (d, J=8.7 Hz, 2H), 7.80-7.63 (m, 8H), 7.63-7.43 (m, 5H), 7.16 (d, J=8.8 Hz, 2H), 5.82-5.66 (m, 1H), 5.37-5.22 (m, 1H), 4.56-4.41 (m, 1H), 4.18-4.00 (m, 1H), 3.93 (s, 3H), 3.12-2.97 (m, 1H), 2.96-2.74 (m, 2H), 2.70-2.56 (m, 1H), 2.43 (s, 3H), 2.41-2.03 (m, 4H), 1.96-1.84 (m, 1H), 1.72 (dd, J=14.6, 7.9 Hz, 1H), 1.51 (d, J=15.0 Hz, 9H), 1.34-1.23 (m, 3H), 1.05 (d, J=14.4 Hz, 9H). 31P-NMR (122 MHz, CD2Cl2) δ (ppm)=141.86. 19F-NMR (282 MHz, CD2Cl2) δ (ppm)=−62.85. HR-MS (ESI) m/z calcd for C32H46NO2PIr [M]+ 700.2895 found 700.2899.

Va-14

The reaction was performed according to the above described procedure using 287 mg of [Ir(COD)2]BARF (0.225 mmol). The complex could be isolated as an orange solid (245 mg; 70% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CDCl3): δ (ppm)=8.38-8.12 (m, 2H), 7.82-7.63 (m, 8H), 7.51 (s, 5H), 7.44-7.17 (m, 2H), 5.81-5.63 (m, 1H), 4.81-4.67 (m, 1H), 4.67-4.49 (m, 1H), 3.57-3.35 (m, 1H), 3.05-2.90 (m, 1H), 2.88-2.61 (m, 3H), 2.36 (s, 3H), 2.31-2.04 (m, 7H), 2.01-1.73 (m, 7H), 1.70-1.48 (m, 6H), 1.42-1.20 (m, 6H), 1.16-0.97 (m, 4H), 0.63-0.40 (m, 1H). 31P-NMR (122 MHz, CDCl3) δ (ppm)=121.31. 19F-NMR (282 MHz, CDCl3) δ (ppm)=−62.43, −106.61. HR-MS (ESI) m/z calcd for C35H47NOFPIr [M]+ 740.3009 found 740.3013.

Va-15

The reaction was performed according to the above described procedure using 287 mg of [Ir(COD)2]BARF (0.225 mmol). The complex could be isolated as an orange solid (180.0 mg; 48% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CD2Cl2): δ (ppm)=8.46 (d, J=7.9 Hz, 2H), 7.94 (d, J=8.0 Hz, 2H), 7.82-7.38 (m, 13H), 5.83-5.69 (m, 1H), 4.94-4.78 (m, 1H), 4.73-4.54 (m, 1H), 3.65-3.38 (m, 1H), 3.15-2.72 (m, 3H), 2.61-2.27 (m, 7H), 2.25-2.04 (m, 4H), 2.04-1.72 (m, 8H), 1.75-1.58 (m, 3H), 1.43-1.22 (m, 8H), 1.19-0.93 (m, 1H), 0.63-0.44 (m, 1H). 31P-NMR (122 MHz, CD2Cl2) δ (ppm)=121.74. 19F-NMR (282 MHz, CD2Cl2) δ (ppm)=−62.88, −63.40. HR-MS (ESI) m/z calcd for C36H47NOF3PIr [M]+ 790.2977 found 790.2990.

Va-16

The reaction was performed according to the above described procedure. The theoretical yield of the ligand was 90%. The complex could be isolated as an orange solid (261 mg; 75% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CD2Cl2): δ (ppm)=8.28-8.11 (m, 2H), 7.93-7.45 (m, 16H), 5.81 (dt, J=9.3, 5.0 Hz, 1H), 4.89 (t, J=6.9 Hz, 1H), 4.72-4.51 (m, 1H), 3.86-3.66 (m, 1H), 3.18-3.04 (m, 1H), 3.04-2.57 (m, 4H), 2.49 (s, 3H), 2.46-1.61 (m, 18H), 1.56-1.36 (m, 5H), 1.36-1.14 (m, 1H), 1.13-0.93 (m, 1H), 0.77-0.66 (m, 1H). 31P-NMR (122 MHz, CD2Cl2) δ (ppm)=129.37. 19F-NMR (282 MHz, CD2Cl2) δ (ppm)=−62.88. HR-MS (ESI) m/z calcd for C33H44NOPIr [M]+ 694.2790 found 694.2789.

Vb-17

The reaction was performed according to the above described procedure. The complex could be isolated as an orange solid (134 mg; 95% purity based on 31P-NMR; 39% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CDCl3): δ (ppm)=8.00-7.92 (m, 2H), 7.81-7.76 (m, 1H), 7.75-7.64 (m, 10H), 7.62-7.55 (m, 2H), 7.52 (d, J=1.9 Hz, 4H), 5.88 (dt, J=8.3, 4.9 Hz, 1H), 4.52 (dt, J=8.3, 4.2 Hz, 1H), 4.37 (ddt, J=7.4, 5.0, 2.5 Hz, 1H), 3.61 (td, J=8.0, 3.8 Hz, 1H), 3.17-2.64 (m, 4H), 2.34-1.79 (m, 9H), 1.68-1.55 (m, 1H), 1.36-0.90 (m, 9H). 31P-NMR (122 MHz, CDCl3) δ=116.36 (mayor product; 95%), 111.79 (minor species; 5%). 19F-NMR (282 MHz, CDCl3) δ=−62.41. HR-MS (ESI) m/z calcd for C2H34NOPIr [M]+ 600.2006 found 600.2006.

Va-18

The reaction was performed (0.5 mmol scale) according to the above described procedure, but after the addition of ClP(iPr)2 was completed, the reaction mixture was stirred at RT for 16 h. The complex could be isolated as an orange solid (605 mg; 85% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CDCl3): δ (ppm)=8.17 (dd, J=7.1, 1.8 Hz, 2H), 7.78-7.40 (m, 16H), 5.74 (dt, J=9.0, 4.7 Hz, 1H), 4.83 (t, J=6.9 Hz, 1H), 4.61 (dt, J=8.7, 4.1 Hz, 1H), 3.62-3.53 (m, 1H), 3.11-2.94 (m, 1H), 2.91-2.67 (m, 2H), 2.67-2.44 (m, 2H), 2.39 (s, 3H), 2.36-1.93 (m, 6H), 1.85 (dd, J=14.5, 7.3 Hz, 1H), 1.46 (dd, J=15.2, 7.1 Hz, 3H), 1.39-1.31 (m, 1H), 1.23 (dd, J=13.3, 6.9 Hz, 4H), 1.08 (dd, J=19.4, 7.1 Hz, 3H), 0.52 (dd, J=15.5, 7.1 Hz, 3H). 31P-NMR (122 MHz, CDCl3) δ (ppm)=129.53. 19F-NMR (282 MHz, CDCl3) δ (ppm)=−62.42. HR-MS (ESI) m/z calcd for C29H40NOPIr [M]+ 642.2477 found 642.2480.

Va-19

The reaction was performed according to the above described procedure. The complex could be isolated as an orange solid (249 mg; 73% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CD2Cl2): δ (ppm)=7.81-7.61 (m, 9H), 7.56 (d, J=2.0 Hz, 4H), 7.34 (d, J=8.0 Hz, 1H), 5.76 (dt, J=8.7, 4.5 Hz, 1H), 5.05-4.84 (m, 2H), 3.74-3.57 (m, 1H), 3.56-3.36 (m, 1H), 3.07 (s, 3H), 3.01-1.49 (m, 23H), 1.42-1.01 (m, 9H), 0.85-0.70 (m, 1H), 0.51-0.25 (m, 1H). 31P-NMR (122 MHz, CD2Cl2) δ (ppm)=126.20. 19F-NMR (282 MHz, CD2Cl2) δ (ppm)=−62.88. HR-MS (ESI) m/z calcd for C29H4NOPIr [M]+ 644.2766 found 644.2762.

Va-20

The reaction was performed according to the above described procedure. The complex could be isolated as an orange solid (164 mg; 42% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CD2Cl2): δ (ppm)=7.86-7.62 (m, 10H), 7.56 (s, 4H), 7.38 (s, 1H), 5.72 (dt, J=8.1, 5.2 Hz, 1H), 4.85-4.63 (m, 2H), 3.80 (s, 3H), 3.49-3.30 (m, 1H), 3.18-2.60 (m, 4H), 2.54-2.23 (m, 6H), 2.23-1.57 (m, 16H), 1.53-1.49 (m, 20H), 1.46-0.93 (m, 10H). 31P-NMR (122 MHz, CD2Cl2) δ (ppm)=123.26. 19F-NMR (282 MHz, CD2Cl2) δ (ppm)=−62.87. HR-MS (ESI) m/z calcd for C44H66NO2PIr [M]+ 864.4460 found 864.4448.

Va-21

The reaction was performed according to the above described procedure. The complex could be isolated as an orange solid (51 mg; 14% based on [Ir(COD)2]BARF).

1H-NMR (400 MHz, CD2Cl2): δ (ppm)=7.80-7.64 (m, 8H), 7.56 (s, 4H), 7.23 (s, 2H), 7.04 (s, 1H), 5.65 (dt, J=5.9, 3.7 Hz, 1H), 5.45-5.35 (m, 1H), 4.04 (ddd, J=8.2, 5.4, 3.6 Hz, 1H), 3.34 (dd, J=11.2, 6.4 Hz, 1H), 3.19-3.08 (m, 3H), 3.06-2.89 (m, 2H), 2.56-2.44 (m, 2H), 2.41 (s, 3H), 2.33-1.84 (m, 9H), 1.84-1.43 (m, 15H), 1.35-1.24 (m, 12H), 1.23-1.14 (m, 5H), 1.09 (dd, J=10.0, 6.8 Hz, 6H), 0.95 (d, J=6.6 Hz, 3H), 0.60-0.46 (m, 1H). 31P-NMR (162 MHz, CD2Cl2) δ (ppm)=119.43. 19F-NMR (282 MHz, CD2Cl2) δ (ppm)=−62.86. HR-MS (ESI) m/z calcd for C4H66NOPIr [M]+ 848.4511 found 848.4512.

Va-22

The reaction was performed according to the above described procedure. The complex could be isolated as an orange solid (274 mg; 73% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CD2Cl2): δ (ppm)=7.79-7.66 (m, 8H), 7.56 (s, 4H), 7.29 (s, 1H), 7.23 (s, 1H), 7.13 (s, 1H), 5.65 (td, J=5.9, 2.2 Hz, 1H), 5.46-5.40 (m, 1H), 4.42-4.36 (m, 1H), 3.38-3.30 (m, 1H), 3.19-2.86 (m, 3H), 2.65 (s, 3H), 2.59-2.44 (m, 2H), 2.42 (s, 3H), 2.38-1.54 (m, 20H), 1.46-0.98 (m, 21H), 0.70-0.58 (m, 1H). 31P-NMR (122 MHz, CD2Cl2) δ (ppm)=118.67. 19F-NMR (282 MHz, CD2Cl2) δ (ppm)=−62.86. HR-MS (ESI) m/z calcd for C41H60NOPIr [M]+ 806.4042 found 806.4053.

Va-23

The reaction was performed according to the above described procedure. The complex could be isolated as an orange solid (15.6 mg; 20% based on [Ir(COD)2]BARF).

1H-NMR (300 MHz, CD2Cl2) δ=8.43-8.36 (m, 2H), 7.92-7.85 (m, 1H), 7.81-7.69 (m, 12H), 7.68-7.53 (m, 4H), 5.73-5.65 (m, 1H), 5.50-5.43 (m, 1H), 4.58-4.43 (m, 2H), 3.25-3.12 (m, 1H), 3.08-2.94 (m, 1H), 2.92-2.77 (m, 1H), 2.72-1.45 (m, 40H). 19F-NMR (282 MHz, CDCl3) δ=−62.42. 31P-NMR (122 MHz, CD2Cl2) δ=134.32. HR-MS (TOF) m/z calcd for C42H54NOPIr [M]+ 812.3572 found 812.3578.

EXAMPLES

Reactions were performed in metal autoclaves. Reaction mixtures were analyzed without workup via HPLC (Chiralpak IC column, 95/5 heptane/ethanol, 1 mL/min) or SFC (OZ-H column, 2.5% MeOH in supercritical CO2, 3 mL/min) chromatography.

Example 1

A 600 mL autoclave was filled with 21 g of 1-(2,2,4-trimethyl-1-quinolyl)ethanone (97.5 mmol, 1 equiv), 0.74 g of catalyst (Va-1) (0.48 mmol, 0.5 mol %) and 450 mL of 2,2,2-trifluoroethanol. The autoclave was pressurized with argon three times, followed by pressurization with hydrogen twice. Subsequently, the autoclave was pressurized with 60 bar of hydrogen, heated to 85° C. and the reaction mixture was stirred at that temperature for 72 h. Chromatographic analysis of the cooled and de-pressurized reaction mixture showed complete conversion of starting material to the hydrogenated product 1-[2,2,4-trimethyl-3,4-dihydroquinolin-1-yl]ethanone (97% a/a purity according to SFC analysis) with an enantioselectivity of >98% ee.

Example 2

A 16 mL autoclave was filled with 0.7 g of 1-(2,2,4-trimethyl-1-quinolyl)ethanone (3.3 mmol, 1 equiv), 4.9 mg of catalyst (Va-1) (3.3 mol, 0.1 mol %) and 4.2 mL of 1,1,1,3,3,3-hexafluor-2-propanol. The autoclave was pressurized with argon three times, followed by pressurization with hydrogen twice. Subsequently, the autoclave was pressurized with 60 bar of hydrogen, heated to 85° C. and the reaction mixture was stirred at that temperature for 16 h. Chromatographic analysis of the cooled and de-pressurized reaction mixture showed 99.3% a/a HPLC conversion of starting material to the hydrogenated product 1-[2,2,4-trimethyl-3,4-dihydroquinolin-1-yl]ethanone with an enantioselectivity of 97.5% ee.

1H-NMR (400 MHz, CDCl3) δ (ppm)=7.12-7.21 (m, 3H), 6.90-6.97 (m, 1H), 2.7-2.83 (m, 1H), 2.09 (s, 3H), 1.83 (d, 1H), 1.72 (s, 3H), 1.49 (s, 3H), 1.35 (d, 2H), 1.22 (t, 1H). UPLC-MS: Re: 1.26 min, UV (210 nm): 100%, m/z (ES+) 218.3. GC-MS: Rt: 4.78 min, m/z (RInt, %): 217 (15), 202 (10), 175 (5), 160 (100).

Example 3

A 16 mL autoclave was filled with 0.52 g of 1-(2,2,4-trimethyl-1-quinolyl)ethanone (2.41 mmol, 1 equiv), 9.2 mg of catalyst (Va-1) (6 mol, 0.25 mol %) and 6 mL of 1,1,1,3,3,3-hexafluoro-2-propanol. The autoclave was pressurized with argon three times, followed by pressurization with hydrogen twice. Subsequently, the autoclave was pressurized with 60 bar of hydrogen, heated to 85° C. and the reaction mixture was stirred at that temperature for 15 h. Chromatographic analysis of the cooled and de-pressurized reaction mixture showed 99.8% a/a HPLC conversion of starting material to the hydrogenated product 1-[2,2,4-trimethyl-3,4-dihydroquinolin-1-yl]ethanone with an enantioselectivity of 96.5% ee.

Example 4

A 100 mL autoclave was filled with 5 g of 1-(6-fluoro-2,2,4-trimethyl-1-quinolyl)ethanone (21.4 mmol, 1 equiv), 65 mg of catalyst (Va-1) (40 mol, 0.2 mol %) and 50 mL of 1,1,1,3,3,3-hexafluoro-2-propanol. The autoclave was pressurized with argon three times, followed by pressurization with hydrogen twice. Subsequently, the autoclave was pressurized with 60 bar of hydrogen, heated to 85° C. and the reaction mixture was stirred at that temperature for 36 h. From the cooled and de-pressurized reaction mixture the solvent was evaporated to dryness under reduced pressure giving 5.6 g of the hydrogenated product 1-(6-fluoro-2,2,4-trimethyl-3,4-dihydroquinolin-1-yl)ethanone (88.9% w/w purity, 98.7% yield) with an enantioselectivity of 98% ee.

Example 5

A 16 mL autoclave was filled with 0.25 g of 1-(2,2-dimethyl-4-propyl-1-quinolyl)ethanone (88.7% a/a HPLC, 1.02 mmol, 1 equiv), 7.8 mg of catalyst (Va-1) (5 μmol, 0.5 mol %) and 5 mL of 1,1,1,3,3,3-hexafluoro-2-propanol. The autoclave was pressurized with argon three times, followed by pressurization with hydrogen twice. Subsequently, the autoclave was pressurized with 60 bar of hydrogen, heated to 85° C. and the reaction mixture was stirred at that temperature for 15 h. Chromatographic analysis of the cooled and de-pressurized reaction mixture showed 92.4% a/a HPLC conversion of starting material to the hydrogenated product 1-(2,2-dimethyl-4-propyl-3,4-dihydroquinolin-1-yl)ethanone with an enantioselectivity of 81.2% ee.

Example 6: Comparison Using Reaction Conditions from Example 6 of DE112015001290 T5

A 25 mL autoclave was filled with 0.5 g of 1-(2,2,4-trimethyl-1-quinolyl)ethanone (2.3 mmol, 1 equiv), 43.9 mg of catalyst (Va-1) (29 mol, 1.2 mol %) and 12.2 mL of 2,2,2-trifluoroethanol. The autoclave was pressurized with argon three times, followed by pressurization with hydrogen twice. Subsequently, the autoclave was pressurized with 70 bar of hydrogen, heated to 90° C. and the reaction mixture was stirred at that temperature for 9 h. Chromatographic analysis of the cooled and de-pressurized reaction mixture showed 70% a/a HPLC conversion of starting material to the hydrogenated product 1-[2,2,4-trimethyl-3,4-dihydroquinolin-1-yl]ethanone with an enantioselectivity of 95.5% ee.

Example 7: Comparison Using Catalyst from Example 6 of DE112015001290 T5

In the comparative example 7 the following commercially available Cy-UbaPHOX (CAS 583844-38-6) catalyst was used:

A 16 mL autoclave was filled with 0.7 g of 1-(2,2,4-trimethyl-1-quinolyl)ethanone (3.3 mmol, 1 equiv), 5.6 mg of catalyst (Cy-UbaPHOX, CAS 880262-14-6) (3.3 mol, 0.1 mol %) and 4.2 mL of 1,1,1,3,3,3-hexafluor-2-propanol. The autoclave was pressurized with argon three times, followed by pressurization with hydrogen twice. Subsequently, the autoclave was pressurized with 60 bar of hydrogen, heated to 85° C. and the reaction mixture was stirred at that temperature for 16 h. Chromatographic analysis of the cooled and de-pressurized reaction mixture showed 84% a/a HPLC conversion of starting material to the hydrogenated product 1-[2,2,4-trimethyl-3,4-dihydroquinolin-1-yl]ethanone with an enantioselectivity of 81.7% ee.

Conclusion from Comparative Examples 6 and 7

Both the catalyst VI-a used in this invention (e.g. example 2) and the reaction conditions are superior to the benchmark catalyst and conditions from DE112015001290 T5 (example 6). For optimal results, the reaction conditions and the catalysts (e.g. Va-1) of this invention have to be used in combination (e.g. example 2). Other catalysts from this invention like Va-4, Va-6, Va-8, Va-10 and Va-22 show even superior activity to both Va-1 and Cy-UbaPHOX.

Detailed Comparison of Experiments with DE112015001290 T5:

Catalyst Conv. ee Example Catalyst [mol %] Solvent [%] [%] DE112015001290 T5, Ir 1.2 Trifluoro- 14.3 31.3 example 6 catalyst (I) ethanol Present invention, Va-1 1.2 Trifluoro- 70 95.5 example 6 ethanol

The comparison shows that catalyst Va-1 of this invention is superior conversion and enantiomeric excess (ee) to Ir catalyst (I) from DE112015001290 T5 (example 6) under the conditions used in DE112015001290 T5, example 6 (1.2 mol % of catalyst in trifluoroethanol).

Catalyst Conv. ee Example Catalyst [mol %] Solvent [%] [%] Present invention, Ir 0.1 Hexafluoroiso- 84 81.7 example 7 catalyst (I) propanol Present invention, Va-1 0.1 Hexafluoroiso- 100 97.5 example 2 propanol

The comparison shows that catalyst Va-1 of this invention is superior in conversion and enantiomeric excess (ee) to Ir catalyst (I) from DE112015001290 T5, example 6 under the conditions used in the present patent application (0.1 mol % of catalyst in hexafluoroisopropanol).

Additionally, the conditions used in the present patent application (0.1 mol % of catalyst in hexafluoroisopropanol) are superior in conversion, enantiomeric excess (ee) and catalyst amount to the conditions used in DE112015001290 T5, example 6 (1.2 mol % of catalyst in trifluoroethanol).

Examples 8-11

Under an inert gas atmosphere, one well of a 96 well-plate autoclave was filled with 9.8 mg of 1-(2,2,4-trimethyl-1-quinolyl)ethanone (45.5 mol, 1 equiv) and 1.82 mol of catalyst (4 mol %, see table 1) in 0.49 mL of 2,2,2-trifluoroethanol. The autoclave was pressurized with 30 bar of hydrogen, heated to 40° C. and the reaction mixture was shaken at that temperature for 16 h. Chromatographic analysis of the cooled and de-pressurized reaction mixture showed the % a/a HPLC conversion rates of starting material to the hydrogenated product 1-[2,2,4-trimethyl-3,4-dihydroquinolin-1-yl]ethanone. The % a/a HPLC conversion rates and enantioselectivities are depicted in table 1 below.

Conversion Ex. Catalyst1) Ligand L* Anion Y (% a/a HPLC) % ee 8 [IrL*(COD)]Y BARF2) 47 89 9 [IrL*(COD)]Y BARF2) 47 93 10 [IrL*(COD)]Y BARF2) 55 91 11 [IrL*(COD)]Y BARF2) 44 51 1)The catalyst used in example 8 was prepared according to the method disclosed in S. Kaiser et al., Angew. Chem. Int. Ed. 2006, 45, 5194-5197; the catalysts used in examples 9 and 10 were prepared according to the method disclosed in W. J. Drury III et al., Angew. Chem. Int. Ed. 2004, 43, 70-74; the catalyst used in example 11 was formed in situ from [Ir(COD)2]BARF and the depicted ligand. 2)BARF = Tetrakis[3,5-bis(trifluoromethyl)phenyl]borate

Examples 12-39

The Ir-complex (catalyst loading given) and 0.64 g 1-(2,2,4-trimethyl-1-quinolyl)ethanone (3 mmol) were placed in an 8-mL autoclave vial containing a PTFE-coated stirring bar. The autoclave vial was closed using a screw cap with septum and flushed with argon (10 min). Hexafluoroisopropanol (HFIP, 4 mL) was added via the septum to the vial. The vial was placed in an argon containing autoclave and the autoclave was flushed with argon (10 min). The autoclave was pressurized with hydrogen gas (10 bar) and subsequently depressurized to atmospheric pressure three times. After this the autoclave was pressurized to 60 bar hydrogen pressure and was placed in a suitable alumina block. After heating to 85° C. the reaction was kept at this temperature for the given time. After cooling to room temperature and depressurizing, the vial was taken out of the autoclave and the reactions outcome was determined by GC-FID analysis (diluted with EtOH) and the enantiomeric excess by HPLC analysis.

Reaction catalyst Conversion Enantiomeric time loading GC excess Example Catalyst (h) (mol %) (% a/a) (% ee) 12 Va-1 16 0.1 99.2 98.0 13 Va-1 6 0.1 81.5 97.5 14 Va-2 6 0.1 94.5 97.5 15 Vb-3 6 0.05 88.2 97.6 16 Va-4 16.5 0.05 94.4 97.3 17 Va-4 16 0.1 99.4 96.0 18 Va-4 16.5 0.1 92.0 97.0 19 Vb-5 16 0.05 98.4 96.8 20 Vb-5 6 0.025 67.2 97.3 21 Va-6 6 0.025 91.6 97.3 22 Vb-7 16.5 0.05 98.9 95.8 23 Vb-7 16.5 0.025 79.5 97.5 24 Va-8 16 0.025 94.1 97.5 25 Va-9 16.5 0.025 81.7 97.9 26 Va-10 16.5 0.025 98.0 98.1 27 Va-11 16.5 0.025 42.2 94.5 28 Va-12 16 0.05 92.4 96.9 29 Va-13 16.5 0.1 91.2 97.0 30 Va-14 16 0.05 64.7 92.4 31 Va-15 16 0.05 34.6 83.2 32 Va-16 16 0.05 87.9 95.8 33 Vb-17 16 0.1 30 90.0 34 Va-18 16 0.1 76.0 96.0 35 Va-19 16 0.025 7.2 70.8 36 Va-20 16 0.025 60 92.1 37 Va-21 16 0.025 74 98.0 38 Va-22 1 0.025 97.5 97.3 39 Va-23 16 0.1 30 94

Claims

1: A process for preparing a compound of the formula (Ia) or (b),

wherein
R1 is C1-C6-alkyl, C1-C6-haloalkyl, C1-C6-alkoxy-C1-C6-alkyl, C3-C6-cycloalkyl, C6-C14-aryl, or C6-C14-aryl-C1-C4-alkyl, wherein the C1-C6-alkyl, C3-C6-cycloalkyl and the C1-C6-alkoxy in the C1-C6-alkoxy-C1-C6-alkyl moiety, are optionally substituted by 1 to 3 substituents independently selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-haloalkyl, C1-C4-haloalkoxy and phenyl, wherein the phenyl may be substituted by one to five substituents selected independently from each other from halogen, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-haloalkyl, and C1-C4-haloalkoxy, and wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy,
R2 and R3 are the same and are selected from the group consisting of hydrogen, C1-C6-alkyl, C1-C6-haloalkyl and C1-C6-alkoxy-C1-C6-alkyl, or
R2 and R3 together with the carbon to which they are bonded, form a C3-C6-cycloalkyl ring,
R4 is hydrogen, C1-C6-alkyl, C1-C6-haloalkyl, C1-C6-alkoxy, C1-C6-haloalkoxy, C1-C6-alkylamino, C2-C6-alkenyl, C2-C6-alkynyl, C3-C6-cycloalkyl, C3-C6-cycloalkyl-C1-C4-alkyl, C2-C6-alkenyloxy, 9-flurorenylmethyleneoxy, C6-C14-aryl, C6-C14-aryloxy, C6-C14-aryl-C1-C4-alkyloxy or C6-C4-aryl-C1-C4-alkyl, wherein the C6-C14-aryl as such or as part of a composite substituent is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy,
n is 0, 1, 2, 3 or 4,
each substituent R5, if present, is independently selected from the group consisting of halogen, C1-C6-alkyl, C1-C6-haloalkyl, C1-C6-alkoxy, hydroxyl, amino and —C(═O)—C1-C6-alkyl,
comprising enantioselective hydrogenation of a compound of the formula (II)
wherein the substituents R1, R2, R3, R4, R5 and the integer n are each as defined for the compound of the formula (a) or (b),
in presence of a chiral iridium catalyst,
characterized in that the chiral iridium catalyst comprises a chiral ligand of the formula (IIIa), (IIIb), (IVa) or (IVb),
wherein
R6, R7 and R8 are independently from one another selected from hydrogen, halogen, C1-C6-alkyl, C1-C6-haloalkyl, C1-C6-alkoxy, C2-C6-alkenyl, C2-C6-alkynyl, C3-C7-cycloalkyl, C3-C7-cycloalkyl-C1-C4-alkyl, C6-C14-aryl and C6-C14-aryl-C1-C4-alkyl, wherein the C1-C6-alkyl, C2-C6-alkenyl, C2-C6-alkynyl, C3-C7-cycloalkyl and the C3-C7-cycloalkyl in the C3-C7-cycloalkyl-C1-C4-alkyl moiety are optionally substituted by 1 to 3 substituents independently selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-alkoxy and C1-C4-haloalkyl and C1-C4-haloalkoxy, and wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety are optionally substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy, C1-C4-haloalkoxy and phenyl, wherein the phenyl again is unsubstituted or substituted by one to five C1-C6-alkyl substituents,
R9 and R10 are independently from one another selected from the group consisting of C1-C6-alkyl, C2-C6-alkenyl, C2-C6-alkynyl, C1-C6-alkoxy, di(C1-C6-alkyl)amino, C3-C12-cycloalkyl, C3-C12-cycloalkyl-C1-C4-alkyl, C6-C14-aryl, C6-C14-aryloxy and C6-C14-aryl-C1-C4-alkyl, wherein the C1-C6-alkyl, C2-C6-alkenyl, C2-C6-alkynyl, C1-C6-alkoxy and di(C1-C6-alkyl)amino are optionally substituted by 1 to 3 substituents independently selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-haloalkyl, C1-C4-haloalkoxy and phenyl, wherein the phenyl may be substituted by one to five substituents selected independently from each other from halogen, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-haloalkyl, and C1-C4-haloalkoxy, and wherein the C6-C14-aryl, C6-C14-aryloxy and C3-C12-cycloalkyl, in each case as such or as part of a composite substituent, are optionally substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy, C1-C4-haloalkoxy and phenyl, wherein the phenyl is unsubstituted or substituted by one to five C1-C6-alkyl substituents or
R9 and R10 together with the phosphorus atom to which they are bonded, form a phospholane ring, which may be substituted with one or two C1-C6-alkyl groups, or
R9 and R10 together form
where the bonds identified by “x” and “y” are both bonded directly to the phosphorus atom,
p and q are independently from one another selected from 0, 1 and 2,
R11 and R12 are independently selected from C1-C6-alkyl and phenyl, which may be substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-alkoxy and phenyl, which may be substituted by one or two C1-C4-alkyl substituents,
m is 1 or 2,
A is
where the bond identified by “*” is bonded directly to the phosphorus atom and where the bond identified by “#” is bonded directly to the oxazoline moiety,
R13 is C1-C6-alkyl, C1-C6-haloalkyl, C3-C2-cycloalkyl, C3-C2-cycloalkyl-C1-C4-alkyl, C1-C4-alkyl-C3-C7-cycloalkyl, C6-C14-aryl or C6-C14-aryl-C1-C4-alkyl, wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy,
R14 and R15 are independently from one another selected from the group consisting of hydrogen, C1-C6-alkyl, C1-C6-haloalkyl, C3-C12-cycloalkyl, C3-C7-cycloalkyl-C1-C4-alkyl, C1-C4-alkyl-C3-C7-cycloalkyl, C6-C14-aryl and C6-C14-aryl-C1-C4-alkyl, wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy, or
R14 and R15 together with the carbon to which they are bonded, form a C5-C6-cycloalkyl ring,
R16 and R17 are independently from one another selected from the group consisting of C1-C6-alkyl, C2-C6-alkenyl, C2-C6-alkynyl, C1-C6-alkoxy, di(C1-C6-alkyl)amino, C3-C12-cycloalkyl, C3-C12-cycloalkyl-C1-C4-alkyl, C6-C14-aryl, C6-C14-aryloxy and C6-C14-aryl-C1-C4-alkyl, wherein the C1-C6-alkyl, C2-C6-alkenyl, C2-C6-alkynyl, C1-C6-alkoxy, C1-C6-cycloalkyl and di(C1-C6-alkyl)amino are optionally substituted by 1 to 3 substituents independently selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-haloalkyl, C1-C4-haloalkoxy and phenyl, wherein the phenyl may be substituted by one to five substituents selected independently from each other from halogen, C1-C4-alkyl, phenyl, C1-C4-alkoxy, C1-C4-haloalkyl, and C1-C4-haloalkoxy, and wherein the C6-C14-aryl, the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl, the C6-C14-aryloxy and C3-C12-cycloalkyl, in each case as such or as part of a composite substituent, are optionally substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, phenyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy, or
R16 and R17 together with the phosphorus atom to which they are bonded, form a phospholane ring, which may be substituted with one or two C1-C6-alkyl groups or
R16 and R17 together form G1 or G2, wherein G1 and G2 are as defined for the substituents R9 and R10 of the ligands of the formulae (IIIa) and (IIIb).

2: The process according to claim 1, wherein

R1 is C1-C6-alkyl or C6-C14-aryl-C1-C4-alkyl, wherein C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy
R2 and R3 are the same and are selected from C1-C4-alkyl,
R4 is C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy, C1-C4-haloalkoxy, phenyl or benzyl,
n is 0, 1 or 2, and
each substituent R5, if present, is independently selected from the group consisting of halogen, C1-C6-alkyl and C1-C6-haloalkyl.

3: The process according to claim 1, wherein

R1 is methyl, ethyl or n-propyl,
R2 and R3 are methyl,
R4 is C1-C4-alkyl,
n is 0, 1 or 2, and
each substituent R5, if present, is independently selected from the group consisting of halogen and C1-C6-alkyl.

4: The process according to claim 1, wherein the chiral iridium catalyst comprises a chiral ligand of the formula (IIa) or (IIIb), wherein

R6 is C1-C6-alkyl, C1-C6-haloalkyl, C3-C7-cycloalkyl or C6-C14-aryl, wherein the C6-C14-aryl is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy, C1-C4-haloalkoxy and phenyl, wherein the phenyl again is unsubstituted or substituted by one to five C1-C6-alkyl substituents,
R7 and R8 are independently from one another selected from the group consisting of hydrogen, C1-C6-alkyl, C1-C6-alkoxy, C6-C14-aryl or C1-C6-haloalkyl, wherein the C6-C14-aryl is unsubstituted or substituted by one to five C1-C4-alkyl substituents,
R9 and R10 are independently from one another selected from the group consisting of C1-C6-alkyl, C1-C6-alkoxy, di(C1-C6-alkyl)amino, C3-C12-cycloalkyl, C6-C14-aryl, C6-C14-aryloxy and C6-C14-aryl-C1-C4-alkyl, wherein the C1-C6-alkyl, C1-C6-alkoxy and di(C1-C6-alkyl)amino moieties are optionally substituted by 1 to 3 substituents independently selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-haloalkyl, C1-C4-haloalkoxy and phenyl, wherein the phenyl may be substituted by one to five substituents selected independently from each other from halogen, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-haloalkyl, and C1-C4-haloalkoxy, and wherein the C6-C14-aryloxy, C3-C12-cycloalkyl and C6-C14-aryl, as such or as part of a composite substituent, in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy, C1-C4-haloalkoxy and phenyl, wherein the phenyl is unsubstituted or substituted by one to five C1-C6-alkyl substituents, or
R9 and R10 together with the phosphorus atom to which they are bonded, form a phospholane ring, which may be substituted with one or two C1-C6-alkyl groups,
m is 1 or 2,
or the chiral iridium catalyst comprises a chiral ligand of the formula (IVa) or (IVb), wherein
A is
where the bond identified by “*” is bonded directly to the phosphorus atom and where the bond identified by “#” is bonded directly to the oxazoline moiety,
R13 is C3-C6-alkyl, C3-C12-cycloalkyl, C6-C14-aryl or C6-C14-aryl-C1-C4-alkyl, wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy,
R14 and R15 are independently from one another selected from the group consisting of C1-C6-alkyl, C6-C14-aryl, C3-C12-cycloalkyl, and C6-C14-aryl-C1-C4-alkyl, wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy, or
R14 and R15 together with the carbon to which they are bonded, form a C5-C6-cycloalkyl ring, and
R16 and R17 are independently from one another selected from the group consisting of C1-C6-alkyl, C3-C12-cycloalkyl, C6-C14-aryl and C6-C14-aryl-C1-C4-alkyl, wherein the C1-C6-alkyl is optionally substituted by 1 to 3 substituents independently selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-haloalkyl, C1-C4-haloalkoxy and phenyl, wherein the phenyl may be substituted by one to five substituents selected independently from each other from halogen, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-haloalkyl, and C1-C4-haloalkoxy, and wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, phenyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy, or
R16 and R17 together with the phosphorus atom to which they are bonded, form a phospholane ring, which may be substituted with one or two C1-C6-alkyl groups.

5: The process according to claim 1, wherein the chiral iridium catalyst comprises a chiral ligand of the formula (IIa) or (IIIb), wherein

R6 is selected from the group consisting of 1-naphtyl, 2-naphtyl, 9-antracenyl, 9-phenantryl or phenyl, which is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-alkyl, C1-C4-haloalkyl and phenyl, wherein the phenyl again is unsubstituted or substituted by one to five C1-C6-alkyl substituents,
R7 and R8 are independently from one another hydrogen or C1-C6-alkyl,
R9 and R10 are independently from one another selected from the group consisting of ethyl, iso-propyl, sec-butyl, iso-butyl, tert-butyl, cyclohexyl, cyclopentyl, adamantyl and benzyl, and
m is 1 or 2,
or the chiral iridium catalyst comprises a chiral ligand of the formula (IVa) or (IVb), wherein
A is
where the bond identified by “*” is bonded directly to the phosphorus atom and where the bond identified by “#” is bonded directly to the oxazoline moiety,
R13 is selected from the group consisting of C3-C6-alkyl, C3-C2-cycloalkyl, C6-C14-aryl or C6-C14-aryl-C1-C4-alkyl, wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen or C1-C4-alkyl,
R14 and R15 are independently from one another selected from the group consisting of C1-C6-alkyl, and C6-C14-aryl-C1-C4-alkyl, wherein the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen and C1-C4-alkyl, and
R16 and R17 are independently from one another selected from the group consisting of C1-C6-alkyl, C3-C12-cycloalkyl, C6-C14-aryl and C6-C14-aryl-C1-C4-alkyl, wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, phenyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy, or
R16 and R17 together with the phosphorus atom to which they are bonded, form a phospholane ring, which may be substituted with one or two C1-C6-alkyl groups.

6: The process according to claim 1, wherein the hydrogenation is conducted using hydrogen gas at a pressure of from 1 to 300 bar.

7: The process according to claim 1, wherein the amount of iridium catalyst used is within the range of from 0.001 mol % to 5 mol %, based on the amount of the compound of the formula (II).

8: The process according to claim 1, wherein the hydrogenation is conducted at a temperature within the range of from 20° C. to 130° C.

9: The process according to claim 1, wherein the hydrogenation is conducted in presence of a solvent selected from the group consisting of 2,2,2,-trifluoroethanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 1,2-dichloroethane, tetrafluoropropanol, and mixtures thereof.

10: The process according to claim 1, wherein the chiral iridium catalyst has the general formula (Va), (Vb), (VIa) or (VIb):

wherein
R6 is selected from the group consisting of 1-naphtyl, 2-naphtyl, 9-antracenyl, 9-phenantryl or phenyl, wherein 1-naphtyl, 2-naphtyl, 9-antracenyl, 9-phenantryl and phenyl are unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-alkyl, C1-C4-haloalkyl and phenyl, wherein the phenyl again is unsubstituted or substituted by one to five C1-C6-alkyl substituents,
R7 and R8 are independently from one another hydrogen or C1-C6-alkyl,
R9 and R10 are independently from one another selected from the group consisting of ethyl, iso-propyl, sec-butyl, iso-butyl, tert-butyl, cyclohexyl, cyclopentyl, adamantyl and benzyl,
m is 1 or 2,
R13 is iso-propyl, sec-butyl, iso-butyl, tert-butyl, phenyl or benzyl,
R14 and R15 are independently from one another selected from the group consisting of C1-C6-alkyl, and C6-C14-aryl-C1-C4-alkyl, wherein the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen and C1-C4-alkyl,
R16 and R17 are independently from one another phenyl, 1-naphthyl or 2-naphthyl, which in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl and C1-C4-haloalkyl, and
R18 is phenyl, which is unsubstituted or substituted with one to five substituents selected from fluorine and C1-C4-haloalkyl.

11: The process according to claim 10, wherein

R6 is selected from the group consisting of phenyl, 2,6- or 3,5-dimethylphenyl, 2,4,6-trimethylphenyl, 4-tert-butylphenyl, 4-methoxyphenyl, 3,5-bis-tert-butyl-4-methoxyphenyl, 4-tert-butyl-2,6-dimethylphenyl, 4-fluorophenyl, 4-trifluoromethylphenyl, 1-naphtyl, 9-antracenyl 2,4,6-triisopropylphenyl, 9-phenantryl or 2,6-diethyl-4-methylphenyl,
R7 is hydrogen,
R8 is hydrogen or methyl,
R9 and R10 are each the same and tert-butyl, adamantly, cyclopentyl or cyclohexyl,
m is 1 or 2,
R13 is tert-butyl,
R14 and R15 are methyl,
R16 and R17 are independently from one another phenyl, which is substituted by one or two methyl, in particular R16 and R17 are each the same and 2-methylphenyl or 3,5-dimethylphenyl, and
R18 is 3,5-bis(trifluoromethyl)phenyl.

12: The process according to claim 1, wherein the chiral iridium catalyst comprises a chiral ligand of the formula (IIIa) or (IIIb), wherein

R6 is selected from the group consisting of 1-naphtyl, 2-naphtyl, 9-antracenyl, 9-phenantryl or phenyl, which is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-alkyl, C1-C4-haloalkyl and phenyl, wherein the phenyl again is unsubstituted or substituted by one to five C1-C6-alkyl substituents,
R7 and R8 are independently from one another hydrogen or C1-C6-alkyl,
R9 and R10 are independently from one another selected from the group consisting of ethyl, iso-propyl, sec-butyl, iso-butyl, tert-butyl, cyclohexyl, cyclopentyl, adamantyl and benzyl, and
m is 1 or 2.

13: The process according to claim 12, wherein

R6 is selected from the group consisting of phenyl, 2,6- or 3,5-dimethylphenyl, 2,4,6-trimethylphenyl, 4-tert-butylphenyl, 4-methoxyphenyl, 3,5-bis-tert-butyl-4-methoxyphenyl, 4-tert-butyl-2,6-dimethylphenyl, 4-fluorophenyl, 4-trifluoromethylphenyl, 1-naphtyl, 9-antracenyl 2,4,6-triisopropylphenyl, 9-phenantryl or 2,6-diethyl-4-methylphenyl,
R7 is hydrogen
R8 is hydrogen or methyl,
R9 and R10 are each the same and tert-butyl, cyclopentyl or cyclohexyl, and
m is 1.

14: The process according to claim 1, wherein the chiral iridium catalyst comprises a chiral ligand of the formula (IVa) or (IVb), wherein

A is
where the bond identified by “*” is bonded directly to the phosphorus atom and where the bond identified by “#” is bonded directly to the oxazoline moiety,
R13 is iso-propyl, sec-butyl, iso-butyl, tert-butyl, phenyl or benzyl,
R14 and R15 are independently from one another selected from the group consisting of C1-C6-alkyl, and C6-C14-aryl-C1-C4-alkyl, wherein the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen and C1-C4-alkyl,
R16 and R17 are independently from one another phenyl, 1-naphthyl or 2-naphthyl, which in each case is unsubstituted or substituted by one to five C1-C4-alkyl substituents.

15: The process according to claim 14, wherein

R13 is tert-butyl,
R14 and R15 are methyl, and
R16 and R17 are independently from one another phenyl, which is substituted by one or two methyl groups.

16: The process according to claim 1, wherein the chiral iridium catalyst comprises a chiral ligand of the formula (IIIa) or (IIIb), wherein

R6 is selected from the group consisting of phenyl, 2,6- or 3,5-dimethylphenyl, 2,4,6-trimethylphenyl, 4-tert-butylphenyl, 4-methoxyphenyl, 3,5-bis-tert-butyl-4-methoxyphenyl, 4-tert-butyl-2,6-dimethylphenyl, 4-fluorophenyl, 4-trifluoromethylphenyl, 1-naphtyl, 9-antracenyl, 2,4,6-triisopropylphenyl, 9-phenantryl and 2,6-diethyl-4-methylphenyl,
R7 is hydrogen,
R8 is C1-C6-alkoxy,
R9 and R10 are independently from one another selected from the group consisting of ethyl, iso-propyl, sec-butyl, iso-butyl, tert-butyl, cyclohexyl, cyclopentyl, adamantyl and benzyl, and
m is 1.
Patent History
Publication number: 20210009521
Type: Application
Filed: Mar 25, 2019
Publication Date: Jan 14, 2021
Applicant: Bayer Aktiengesellschaft (Leverkusen)
Inventors: Christoph SCHOTES (Düsseldorf), Dirk Eckart BROHM (Mettmann), Johannes SCHRANCK (Basel)
Application Number: 17/041,907
Classifications
International Classification: C07D 215/08 (20060101); B01J 31/18 (20060101); B01J 31/22 (20060101); B01J 31/24 (20060101);