Lactams. IX. Generation of Lactam Carbonyl Function in 1,3-Disubstituted Piperidines by Mercuric Acetate-EDTA Oxidation : Effects of Hydrocarbon Substituents at the 3-Position
The mercuric acetate-(ethylenedinitrilo) tetraacetic acid oxidation of 1-(3,4-dimethoxyphenyl)-2-(3-substituted piperidino) ethanols (7c-f), which carry the n-butyl, isopropyl, benzyl, and phenyl group as the 3-substituent in the piperidine ring, has been found to produce the corresponding 2- (8c-f) and 6-piperidones (12c-f) in good yields in ratios of 41 : 59,29 : 71,26 : 74,and 15 : 85. It is suggested that the 3-substituents exert both steric and electronic effects. The structures of the lactam alcohols (8c-f, 12c-f) have been confirmed by the chemical correlation with the known pyridones (11c-f, 15c-f) through the lactams (10c-f, 14c-f). The starting piperidinoethanols (7c-f) have been synthesized from the 3-substituted pyridines (5c-f) by quaternization with 3,4-dimethoxyphenacyl bromide followed by catalytic and sodium borohydride reductions
