Procédé de préparation de cétones non saturées

Ketones, which are intermediates in the synthesis of vitamin A or perfumes, and have the general formula: R2R3 ¦¦ CCH2CR6O (I) ANGLE ANGLE ANGLE ¦ PARALLEL R1--CH2CHCHC-CH2-C-C-R8 n¦¦¦ R4R5R7 wherein R1 is hydrogen or C1-10 hydrocarbon, R2 and R3 are hydrogen or C1-4 alkyl, R4 and R5 are hydrogen or together form a -CH2-CH2-C(CH3)2- group, R6 and R7 are hydrogen or C1-10 hydrocarbon, or together with the carbon atom to which they are joined form a hydrocarbon ring of up to 10 carbons, or ¦ R6-C-C-R8 ¦ PARALLEL R7O forms a hydrocarbon ring of up to 10 carbons joined through R6 and R8 or R7 and R8, R8 is hydrogen or C1-10 hydrocarbon and n is 0-6, are prepared by reacting an unsaturated halide of formula R2R3 ¦¦ CCH2CCH2X (II) ANGLE ANGLE ANGLE ¦ R1--CH2CHCHC n¦¦ R4R5 wherein X is halogen, with an enol ester of formula R6 ANGLE C=C-R8 (III) ¦ R7OOC-R9 wherein R9 is C1-20 hydrocarbon, in the presence of a metal catalyst.