Enamine chemistry. Part XIII. Reaction of αβ-unsaturated acid chlorides with primary and secondary enamines. Synthesis of tetrahydro-2-oxopyridines and octahydro-2-oxoquinolines
Abstract
αβ-Unsaturated acid chlorides react with primary and secondary enamines, obtained by condensation of ammonia or primary amines with β-diketones or β-keto-esters, to give tetrahydro-2-oxopyridines or octahydro-2-oxoquinolines. The evidence available from this and previous work suggests that the reaction involves initial O- or N-acylation followed by a [3,3] sigmatropic rearrangement and cyclisation of the keten intermediate formed on to the nitrogen atom.