Studies on the Steric Inversion of Alkamines. II

On the Reciprocal Inversion between dl-Ephedrine and dl-Ψ-Ephedrine. (Part 2)

Abstract

dl-Ephedrine is quantitatively obtained by heating dl-Ψ-1-phenyl-1-chloro-2-benzoyl (or-acetyl)-methylaminopropane (IV or V) with NaOH solution with an intermediary formation of N-benzoyl (or-acetyl)-dl-ephedrine (VII or VIII). No by-product of dl-Ψ-ephedrine could be noticed. Heating (IV) or (V) with aqueous EtOH gives O-benzoyl (or-acetyl)-dl-ephedrine hydrochloride (IX or X) which, when saponified with dil. HCl, gives only dl-ephedrine hydrochloride. By these experiments, it became clear that when Cl is substituted with OH under the presence of N-acyl radical, Walden conversion from pseudo to normal system occurs. It is assumed that the formation of (IX) and (X) occurs with N→O transition of acyl radical by the liberated HCl after substitution and conversion.