GB802534A - A process for the production of pseudoionones or homologues of pseudoionones - Google Patents

Abstract

Mixtures of stereoisomeric pseudoionones or of homologues of such stereoisomers are prepared by heating a mixture of dehydrolinolool and an excess on a molar basis of an acetoacetic ester having the general formula <FORM:0802534/IV (b)/1> wherein R1, R2, R3 and R4 may be hydrogen or alkyl or alkenyl groups and R is the radical of a primary or secondary alcohol ROH possessing a lower B.P. than that of dehydrolinalool, such as methyl, ethyl, isopropyl or benzyl alcohol, the heating being effected at a temperature from 160 DEG to 180 DEG C. sufficiently high to produce a reaction comprising simultaneously the alcoholysis of the ester and the intramolecular rearrangement accompanied by decarboxylation of the ester resulting from the alcoholysis, and thereafter isolating the resulting pseudoionones or homologues thereof as an isomeric mixture by distillation of the reaction product. The recovered mixtures may be cyclized to the corresponding ionones by treatment with BF3 according to the method of Specification 666,881. In examples: (1) dehydrolinalool is heated with 3 mols. of ethyl aceto acetate at 160 DEG C. with stirring for 36 hours during which ethanol and CO2 distil off as formed and the product is fractionated under reduced pressure; the pseudo-ionones recovered are cyclized to give a -ionones and some b -ionones; (2) ethyl a -methyl aceto acetate is reacted similarly at 180 DEG C., yielding stereoisomeric 9-methyl pseudo-ionones which are cyclized to 22-methylionones; (3) ethyl propionyl acetate is reacted as in (1) yielding the 11-methyl pseudo ionones which are cyclized to 24-methyl-ionones. Specifications 646,962, 733,884, 741,047, and 762,656, also U.S.A. Specification 2,167,168, are referred to.