Patent ID: 8871982

Claim:
A process for the reduction by hydrogenation, using molecular H 2 , of a C 6 -C 20 conjugated dienal of formula wherein, when taken separately, each of R 1 , R 2 , R 3 , R 4 and R 5 represents, independently of each other, a hydrogen atom, a phenyl group optionally substituted or a C 1-8 alkyl, alkenyl, cycloalkyl or cycloalkenyl group optionally substituted, provided that at least one of said R 1 , R 2 , R 3 , R 4 and R 5 is not a hydrogen atom; R 1 and R 2 or R 2 and R 3 or R 3 and R 4 , when taken together, represent a C 3-4 alkadienyl or alkenediyl group optionally substituted; R 1 and R 3 or R 2 and R 5 , when taken together, represent a C 2-3 alkadienyl or alkenediyl group optionally substituted; R 4 and R 5 , when taken together, represent a C 4-5 alkadienyl or alkenediyl group optionally substituted; and the substituents of R 1 to R 5 are one phenyl group or one, two or three COOR 7 , OR 6 or R 7 groups, in which R 6 is a hydrogen atom or a R 7 group, R 7 representing a C 1-4 linear or branched alkyl or alkenyl group; into a deconjugated enal of formula wherein R 1 to R 5 are defined as in formula (I); said process being carried out in the presence of a catalytic system comprising: at least a base; and at least one Rh(I) complex obtainable by reacting together : a C 34 -C 60 bidentate diphosphine ligand (L2) having a natural bite-angle comprised between 93° and 130°; and a suitable Rh(I) precursor of formula wherein r is 0 or 1, v is 0, 1 or 2; L represents a C 5-14 hydrocarbon diene; S represents a coordinated molecule of a polar organic solvent or water; and Y represents a mono-anion.