Novel Use of <i>N</i>-Benzoyl-<i>N,O</i>-acetals as <i>N</i>-Acylimine Equivalents in Asymmetric Heterocycloaddition: An Extended Enantioselective Pathway to β-Benzamido Aldehydes

Abstract

For the first time, easily available N-(alpha-methoxyalkyl)amides were successfully used as synthetic equivalents of N-acylimines in an asymmetric heterocycloaddition process. The facial-controlled formation of 6-alkoxydihydrooxazines was thus achieved by SnCl(4)-promoted heterocycloaddition of (R)-O-vinyl pantolactone. By simple acidic hydrolysis of the crude heteroadducts, new beta-aryl- and beta-alkyl-substituted benzamido aldehydes were thus obtained in good overall yields with high enantioselectivities.