Synthesis of enantiomerically pure acyclic α-sulfinyl ketimines

Two different methods to obtain enantiomerically pure N-alkyl and N-aryl alpha-sulfinyl ketimines are reported. Reaction of enantiomerically pure alpha-sulfinyl ketones (1-6) with benzylamine or p-methoxyaniline, in the presence of molecular sieves (3 Angstrom), yields the corresponding of N-benzyl and N-p-methoxyphenyl ketimines (7A-12A and 7B-12B). Better results were achieved by alpha-sulfinylation of ketimines (13A-18A and 13B-18B) with (-)-menthyl p-toluenesulfinate in the presence of lithium (N-arylimines) or magnesium (N-benzylimines) bases. The different tautomeric behaviour of the obtained N-aryl and N-alkyl derivatives is reported. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.