Ketene S,S-acetals as 1,3-dipolarophiles: application to the synthesis of polyhydroxylated pyrrolidines

Abstract

Two approaches to the synthesis of the hydroxylated pyrrolidines 3 and 4, based on exploiting the reactivity of a ketene S,S-acetal as a 1,3-dipolarophile, are described. Both routes utilize a carbohydrate starting material and the strategy based on D-erythrose was successfully concluded. The use of D-ribose, although not successful in terms of the synthetic objectives, does serve to probe the scope and limitations of ketene S,S-acetals as highly functionalised dipolarophiles.