Diastereoselectivity in the intramolecular cycloaddition reactions of nitrones derived from 5-alkenals and chiral hydroxylamines

Intramolecular cycloaddition of the nitrones derived from a series of 5-alkenals and α-methylbenzyl hydroxylamine leads to mixtures of diastereomeric products in the range of 1.7/1 to 16/1. Cyclization of a series of fifteen 5-alkenyl nitrones with a chiral group on nitrogen afforded diastereomeric isoxazolidines in ratios ranging from 1.7/1 to 16/1. When R* = (S)-α-methylbenzyl, C6a of the major product was also S in those cases known.