Lewis acid induced additions to unsaturated fatty compounds IV: Synthesis of cyclopentenones from Friedel‐ Crafts acylation products of unsaturated fatty compounds with α,β‐unsaturated acyl chlorides

Abstract

AbstractThe ethylaluminium dichloride induced Friedel‐ Crafts acylation of unsaturated fatty compounds such as oleic acid (1a), methyl oleate (1b) and 10‐undecenoic acid (9b) and furthermore of 1‐octene (9a) with α,β‐unsaturated acyl chlorides e.g. crotonic acid chloride (2a) and acrylic acid chloride (2b) gave the corresponding allyl vinyl ketones. Nazarov cyclizations of the acylation products 3a/4a, 3b/4b, 10a and 10b afforded the alkyl substituted 2‐cyclopentenones 5a/6a, 5b/6b, 11a/12a and 11b/12b. Catalytic hydrogenation of 5b/6b and 11b/12b gave the respective saturated cyclic products 7b/8b and 13b/14b as diastereomeric mixtures.