Asymmetric induction in silyl nitronate cycloadditions to Oppolzer's chiral sultam derivatives

Abstract

Silyl nitronate cycloadditions to Oppolzer's chiral sultam derivatives, followed by the elimination of the silyl alcohols from the resulting N-silyloxyisoxazolidines, provide Δ 2-isoxazolines in good stereoselectivity (ca. 89/11). The favored transition state is suggested in the light of the X-ray crystal structure of a major cycloadduct.