On the Scope of Asymmetric Nitrile Oxide Cycloadditions with Oppolzer's Chiral Sultam. Total Syntheses of (+)-Hepialone, (-)-(1R,3R,5S)-1,3-Dimethyl-2,9-dioxabicyclooctane

Article abstract of DOI:10.1021/jo00302a023

Cycloadditions of nitrile oxides with acryloyl derivatives of Oppolzer's chiral sultam produce stereoisomeric Δ²-isoxazolines in ratios of about 90/10 at 25 deg C.The major diastereomers can be isolated in pure form in 70-88percent yield.Synthe