Synthesis, stereochemistry, and transformations of (E)-1,2-bis(benzenesulfonyl)ethylene cycloadducts to 2-oxa substituted 1,3-dienes

Abstract

The cycloaddition of (E)-1,2-bis(benzenesulfonyl)ethylene (2) to 2-acetoxy- and 2-silyloxy-1,3-cyclodienes occurs in high yields and with high steroselectivity. Structure assignment has been based largely on 1H nmr nuclear Overhauser effect (nOe) experiments on the isolated products. The cycloadducts 4a and 4b derived from the 2-oxa substituted cyclopentadienes have been further elaborated to the parent norbornenone, to the respective unsaturated sulfones 5, and to the β-hydroxy substituted sulfone 6. The vinyl sulfones 5 have also been independently synthesized via cycloaddition of benzenesulfonyl acetylene. The sulfones obtained are potentially important starting molecules for the preparation of more complex targets.