Diastereoselectivity in the aza-diels-alder reaction of a sulfonyl imino acetate with danishefsky's diene

Abstract

N-(1 R)-Camphorsulfonyl imine 8, generated in situ from the corresponding brominated glycine derivative, reacted with Danishefsky's diene under thermal conditions at room temperature, to give a high yield of a 2.04 : 1 ratio of diastereomeric Diels-Alder adducts after acid hydrolysis. The observed diastereoselectivity was reversed when catalytic amounts of certain Lewis-acids were used, but was unaltered with others. The highest diastereoselectivity was 2.30 : 1 with titanium tetraisopropoxide at −78°C.