Stereochemistry of alpha-cyanation of 4-acetamido-1-methylpiperidine

Alpha-cyanation of 4-acetamido-1-methylpiperidine [1] was carried out by reacting the corresponding N-oxide 2 with p-toluenesulphonyl chloride followed by the addition of KCN. 1H-NMR analysis of the produced aminonitrile indicated that the addition of cyanide ion to the iminium intermediate 5, that has been generated in the reaction, occurred in stereospecific manner to afford the transdiastereomer 6b