New general synthesis of alpha-alkoxyketones via alpha'-alkylation, alpha-alkylation and alpha,alpha'-dialkylation of alpha-alkoxyketimines

摘要

alpha-Methoxy- and alpha-ethoxyketones, as important intermediates in organic synthesis and flavor compounds in food chemistry, were synthesized by deprotonation of N-(1-alkoxy-2-propylidene)isopropylamine, prepared by condensation of the corresponding alpha-alkoxyacetone with isopropylamine, and subsequent reaction of the corresponding 1-azaallylic anions with alkyl halides to afford alpha'-alkylated, alpha-alkylated and alpha,alpha'-dialkylated ketimines. Hydrolysis of the imino function led to the desired substituted alpha-alkoxyketones. The ratio of alpha-, alpha'-, and alpha,alpha'-(di)alkylated compounds depended on the amount of base used and on the nature of the alkylating reagent.