The Diels‐Alder Reaction of 2,3‐Disulfur‐Substituted 1,3‐Butadienes

Abstract

Abstract The 2,3‐disulfur‐substituted 1,3‐dienes (1) can be readily prepared from their stable 3‐sulfolene precursors (2) by thermal extrusion of SO 2 . The Diels‐Alder reaction of diene (1) with several dienophiles has been studied. The substituent effect on the reactivity and regioselectivity follows the order of PhS >PhSO >PhSO 2 . Lewis acid can greatly increase the regioselectivity of this reaction. The diene (1c), bearing a strong electron‐withdrawing sulfonyl group, also reacted as a dienophile.