Alkylation of 4-piperidones; intermediates in the synthesis of reduced 2-pyrindin-6-ones

Abstract

Alkylation experiments on 1-benzoyl- and 1-alkyl-4-piperidones are described, producing a number of 1-substituted 3-acetonyl-4-piperidones. 3-Acetonyl-1-benzyl-5-methyl-4-piperidone has been cyclised to give a hexahydropyrindin-6-one, an analogue of the alkaloid tecomanine, but other 3-acetonyl-4-piperidones failed to cyclise. 1-Phenyl-4-piperidone could not be alkylated either by way of the enolate or by way of the enamine. Two other unsuccessful attempts to prepare pyrindinones are described; the first proceeding via a 3-ethoxycarbonyl-4-piperidone, and the second via 4-chloro-3-cyanomethyl-1,5-dimethylpiperidine.