Detailed investigations into the Akabori-Momotani reaction for the synthesis of amphetamine type stimulants: Part 2.

The Akabori-Momotani reaction can be used to synthesise pseudoephedrine in 50% yield from N-methylalanine and benzaldehyde. This paper investigates electronic effects of substituted benzaldehydes on the reaction to synthesise amphetamine type stimulants and identifies several new Akabori-Momotani by-products, 1-[(4-methoxybenzyl)(methyl)amino]ethanol (11c), 2-(4-methoxyphenyl)-3,4-dimethyl-1,3-oxazolidine (12c), 1,2,3,4-tetramethyl-5,6-di-(4-methoxyphenyl)piperazine (13c) and 1,2,4,5-tetramethyl-3,6-di-(4-methoxyphenyl)piperazine (14c). This paper also investigates pseudoephedrine and methamphetamine isomeric distribution from the Akabori-Momotani reaction with the aid of molecular modelling to understand why more pseudoephedrine than ephedrine is produced.