Unsaturated carboxylic acid polyenolates. Lithium trienolate of sorbic acid as a d6 synthon: addition to ketones and unsaturated ketones

Abstract

Deprotonation of sorbic acid by two equivalents of lithium diethylamide, and aldol-type reaction of the resulting trienolate dianion (2) with carbonylic compounds affords the pentadienyl hydroxy acids (6) or 7-hydroxyhexa-2,4-dienoic acids (7) according to the duration and temperature of the reaction. The reaction of the dianion (2) with α,β-unsaturated ketones gives 1,4-ε-adducts for di- or tri-substituted enones, but either 1,4-γ- or 1,4-α-adducts for monosubstituted enones.