The Michael Addition of Diethyl Methylmalonate to Ethyl Crotonate-(carbonyl C14). A Contribution to the Elucidation of the Mechanism of the Abnormal Addition

Abstract

Abstract The Michael addition of diethyl methylmalonate to ethyl crotonate-(carbonyl-C14) was carried out with one equivalent of sodium ethoxide; the addition product, diethyl α-ethoxycarbonyl-β,γ - dimethylglutarate, was hydrolyzed and the resulting acid decarboxylated by heating. The evolved carbon dioxide contained 42 % of the radiocarbon of the original ethyl crotonate. Thus it was demonstrated that the migration of an ethoxycarbonyl group took place in the course of the reaction from the methylmalonate moiety to the carbon atom α to the labelled ethoxycarbonyl group. The mechaism of the reaction is discussed.