Process for the manufacture of 3-hydroxy-2,6,6,-trimethyl-2 cyclohexen-1-one

摘要

A process for the manufacture of 3-hydroxy-2,6,6,-trimethyl-2-cyclohexen-2-one, an intermediate in canthaxanthin synthesis, by isomerizing 1,1,3-trimethyl-7-oxabicyclo[4.1.0]heptan-2-one in the presence of a palladium(O) complex of an acetone derivative of the formula <IMAGE> III wherein R1 and R2 are aryl and R3 and R4 are hydrogen or monovalent hydrocarbon groups optionally carrying a carbonyl function, a bis-(diphenylphosphino) derivative of the formula (R5)2P-R6-P(R5)2 wherein R5 is phenyl or tolyl and R6 is a C2-C4-alkylene group optionally substituted with one or more inert organic groups, and a triarylphosphine of the formula P(R7)3 wherein R7 is an optionally alkyl-substituted phenyl group.