Abstract: The present invention relates to a transesterification process of specific compounds comprising isoprenoid units.

Abstract: The present invention relates to a transesterification process of specific compounds comprising isoprenoid units.

Abstract: The present invention relates to a process for the preparation of ?-ionones and/or ?-ionones of the formulae (II) and (III) by acid catalyzed ring-closing of ?-ionone of the formula (I) wherein R1 to R7 are independently selected from hydrogen and C1-C4-alkyl, R8 is selected from hydrogen and C1-C4-alkyl and the hydroxyl group, R9 and R10 are independently selected from hydrogen and C1-C4-alkyl or R9 and R10 form together the oxygen of a carbonyl group, whereby if R9 and R10 form together the oxygen of a carbonyl group no ?-isomer is formed comprising: a) reacting a ?-ionone according to formula (I) in presence of a concentrated Brønsted-acid having a pKs<3, and an organic solvent that is substantially immiscible with the concentrated acid and with an diluted aqueous solution of said acid; b) hydrolysis of the reaction product obtained in step a) by addition of water; and phase separation into an organic phase comprising the ?-ionone and/or the ?-ionone of the formulae (II) and (III) and into an aqueous di

Abstract: The invention relates to a process comprising a condensation step wherein a starting aldehyde or ketone is made to react with an ester of an ?-haloacid to form an epoxy compound, whereby the reaction is carried out in the presence of a dipolar aprotic compound selected from the group consisting of 1-methyl-2-pyrrolidone (NMP), hexamethylphosphorous triamide (HMPT), dimethylsulfoxide (DMSO), and urea derivatives of the following formula: (III) wherein R1, R2, R3 and R4 may each independently be H or a C1-C4 alkyl group and whereby R2 and R3 may together form a heterocyclic group.

Abstract: A process for the manufacture of certain cycloalkenylalkenes, e.g. vitamin A acetate, comprises dehydrating 1-(5-acetoxy-3-methyl-penta-1,3-dienyl)-2,6,6-trimethyl-cyclo hexanol or 4 aetoxy-1-(5-acetoxy-3-methyl-penta-1,3-dienyl)-2,6,6-trimethyl-cyclohexano l or 1-(9-acetoxy-3,7-dimethyl-4-hydroxy-nona-2,5,7-trienyl)-2,6,6-trimethyl- cyclohexene in the presence of an alkali metal bromide or of manganese bromide or of a hydrate of such a bromide as the catalyst and in an organic solvent.The products are especially suitable as intermediates in carotinoid syntheses.