REGIOCHEMICAL AND STEREOCHEMICAL STUDIES ON HALOGEN-INDUCED RING EXPANSIONS OF UNSATURATED EPISULFIDES

摘要

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 beta,beta'-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 moiety 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. [References: 90]