Aldol Type Condensations of β-Keto Ester Dianions

Abstract

The dianion of methyl acetoacetate reacts with ketones and aldehydes to yield δ -hydroxy-β-keto esters. These hydroxy esters can be dehydrated to the corresponding γ,δ-unsaturated-β-keto esters which are useful in annelation reactions to form cyclic β-keto esters. The dianion of methyl acetoacetate does not appear to undergo conjugate addition to simple α,β-unsaturated ketones, instead only carbonyl addition occurs.