Synthesis of New Sulfoxide-Containing Diselenides and Unexpected Cyclization Reactions to 2,3-Dihydro-1,4-benzoselenothiine 1-Oxides

New chiral sulfoxide-containing diselenides were prepared and their corresponding selenium electrophiles were used for the stereoselective functionalization of alkenes. The influence of solvents and different nucleophiles on the outcome of the selenenylation reaction was studied. Besides the successful selenenylation reactions, one selenium electrophile showed an unexpected reactivity in forming a six-membered heterocyclic system upon reaction with alkenes. A mechanism for the formation of these 2,3-dihydro-1,4-benzoselenothiine 1-oxides is proposed.