| abstract |
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 ##STR1## wherein R 1 and R 2 are aryl and R 3 and R 4 are hydrogen or monovalent hydrocarbon groups optionally carrying a carbonyl function, a bis-(diphenylphosphino) derivative of the formula n n (R.sup.5).sub.2 P--R.sup.6 --P(R.sup.5).sub.2 n n wherein R 5 is phenyl or tolyl and R 6 is a C 2 --C 4 -alkylene group optionally substituted with one or more inert organic groups, and a triarylphosphine of the formula n n P(R.sup.7).sub.3 n n wherein R 7 is an optionally alkyl-substituted phenyl group. |