Annelation Reactions of Enaminones with Ethyl Acetoacetate. Studies on the β-Carbonyl Compouds Connected with the β-Polyketides. XI

Abstract

Though condensation at either the carbonyl oxygen or the unsaturaced carbon adjacent to nitrogen of enaminones can occur in the reaction with the active methylene of ethyl acetoacetate, the results obtained in the condensation reactions of the enaminones 1 and 2 with ethyl acetoacetate in the presence of Knoevenagel catalysts to give the α-pyranones 3 and 4 and with the dianion of ethyl acetoacetate to give the ethyl salicylates 6 and 19 show that these reactions proceed at the latter position.