Condensation of ynamines or ketene-N,N-acetals with aminoesters : Syntheses of 5- and 6-membered nitrogen-containing heterocycles

Abstract

The addition of primary or secondary aminoesters to ynamines leads to N,N,N′-trisubstituted amidines or to ketene-N,N-acetals. Both these classes cyclise on heating by an intramolecular acylation. Starting from α- or β-aminoesters 5- or 6-membered nitrogen-containing heterocycles are obtained. The same heterocycles have been also prepared from ketene-N,N-acetals and aminoesters via transamination. Under these reaction conditions γ-aminoesters from γ-lactams.