Synthesis and Diels-Alder reactions of enantiopure (-)-trans-benzo[d]-dithiine-S,S'-dioxide

Enantiopure (-)-trans-benzo[d] dithiine-S,S'-dioxide 4 was obtained by enantioselective oxidation of the parent benzo[d]dithiine. The reaction of the bis-sulfoxide with a series of cyclic dienes affords the corresponding Diels-Alder cycloadducts with diastereoselectivities ranging from fair to high and good chemical yields