A general and convenient synthesis of beta-ketols and alpha,beta-alkenones has been achieved by a Knoevenagel condensation of a beta-ketoacid with an aldehyde in aqueous medium. Saponification of a beta-ketoester by an aqueous KOH 10% solution gives the potassium salt of the beta-ketoacid, which is condensed in situ with an aldehyde at pH 7.8-8.0, at 60 degrees C for 5-6 h. The intermediate beta-ketocarboxylate is smoothly decarboxylated in the reaction medium, giving the beta-ketol in high yield (75-90%). Acidification of the reaction mixture at pH 1 and heating at 70 degrees C under vigorous stirring for 6 h, leads directly to the corresponding alpha,beta-unsaturated ketone in good yield (65-75%).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.