Regiochemical and Stereochemical Studies on Halogen-Induced Ring Expansions of Unsaturated Episulfides

Article abstract of DOI:10.1021/jo00125a039

The reactions of unsaturated episulfides with bromine and iodine have been studied.Initially produced in the reaction is a ring-opened sulfenyl halide intermediate, which in the presence of the carbon-carbon double bond or triple bond cyclizes to β,β'-dihalo sulfide cycloadducts.The regiochemistry and relative stereochemistry of these cyclizations have been examined as a function of the length of the tether between the episulfide and the unsaturated functionality, the presence of alkyl substituents, and the type of unsaturation.A discussion of the mechanistic and stereochemical features of the ring-expansion process is presented.