Condensations of Ethyl 3-Ethoxy-4-(triphenylphosphoranylidene)-2-butenoate with alpha,beta-Unsaturated Carbonyl Compounds

摘要

Witting condensations of alpha,beta-unsaturated carbonyl compounds with ethyl 3-ethoxy-4-(triphenylphosphoranylidene)-2-butenoate gave good to high yields of (2E,4E,6E)-ethyl 3-ethoxy-2,4,6-alkatrienoates. Some of last mentioned compounds were almost quatitatively hydrolysed to (4E,6E)-ethyl 3-oxo-4,6-alkadienoates. This method can therefore be used as an attractive alternative for the preparation of unsaturated conjugated beta-keto esters previously prepared in very low yields from alpha,beta-unsaturated carbonyl compounds and ethyl 3-oxo-4-(triphenylphosphoranylidene)butanoate.