The stereoselectivity of the oxidation of N-alkylpiperidines was studied with the aid of the conformationally biassing 4-tert-butyl substituent. The stereoselectivity was always 795% and showed little sensitivity to the nature of the N-alkyl substituent. The axial approach was found to be the predominating stereochemical oxidation path. A brief study of the effects of solvent, temperature, and oxidant on the stereoselectivity was made. The 1, 4- ...