Regulation of Diastereofacial Selection in the Allylation Reaction of N-Acyliminium Ion Utilizing Lewis Acids

Diastereofacial selectivity in the α-allylation reaction of chiral cyclic α-acyloxy amide, derived from succinic anhydride and (R)-2-methoxy-1-phenylethylamine could be regulated using appropriately selected Lewis acids; i.e., the reaction using Lewis acids such as TiCl4 gave (R,S)-α-allylated amides, while allylation promoted by SnCl4 afforded (R,R)-isomers stereoselectively. The similar result was obtained in the reaction of chiral amide prepared from phthalic anhydride.