Hexacarbonylmolybdenum(0)-Induced Dechalcogenization of Allylic Sulfides, Sulfones, and Selenides: Nucleophilic Substitution and Reductive Dechalcogenization

Abstract Hexacarbonylmolybdenum(0)-induced dechalcogenization of allylic sulfides I, sulfones II, and selenides III in refluxing dioxane, which led to nucleophilic substitutions with carbon nucleophiles. Attack of the relatively bulky nucleophile, 2-ethoxycarbonyl-2-sodiocyclopentanone occurred regioselectively at the less substituted end of the allyl unit after the dechalcogenization to give only one isomer. Attack of diethyl sodiomalonate to I and III occurred preferentially at γ-position, and that to II occurred preferentially at the more substituted end of the allyl unit after the desulfonylation. In the absence of the carbon nucleophiles, treatment of I, II, and III with Mo(CO)6 in refluxing dioxane caused reductive dechalcogenization. Addition of H2O accelerated the reductive dechalcogenization.