Abstract: The invention is concerned with new phosphine ligands of formula I wherein R1 and R2 are independently of each other unsubstituted alkyl, aryl, cycloalkyl or heteroaryl, or alkyl, aryl, cycloalkyl or heteroaryl each of which independently is substituted by alkyl, alkoxy, halogen, hydroxy, amino, mono- or dialkylamino, aryl, —SO2—R7, —SO3?, —CO—NR8R8?, carboxy, alkoxycarbonyl, trialkylsilyl, diarylalkylsilyl, dialkylarylsilyl or triarylsilyl; R3 is alkyl, cycloalkyl, aryl or heteroaryl; R4? and R4 are independently of each other hydrogen, alkyl or optionally substituted aryl; or R4? and R4 together with the C-atom they are attached, form a 3-8-membered carbocyclic ring; dotted line is optionally a double bond; R5 and R6 are independently of each other hydrogen, alkyl or aryl, R7 is alkyl or aryl; and R8 and R8? are independently of each other hydrogen, alkyl or aryl; the substituents attached by the bold bonds are in cis relation to each other; metal complexes with such ligands in asymmetric reactions.

Abstract: The invention is concerned with new phosphine ligands of formula I 1