Preparation and Stereochemistry of N-Methyl-N-phenacylpiperidinium Salts

Abstract

The N-methyl-N-phenacylquaternary salts of 2-, 3-, and 4-methylpiperidines have been prepared and characterized. N.m.r. spectroscopy was employed in analyzing the proportion of diastereomers formed following reciprocal alkylations with methyl iodide and phenacyl halides. Preferential axial attack was observed with N-methylation while N-phenacylation primarily proceeded by equatorial attack.