Generation and intramolecular cyclization of α-phenylsulfonyl and α-alkylsulfonyl radicals

Article abstract of DOI:10.1016/S0040-4020(97)00156-7

α-Phenylsulfonyl radicals are generated by the reaction of diphenyl dithioacetals or phenyl α-chlorosulfides with tributyltin hydride. Alkyl phenyl dithioacetals react selectively with tributyltin hydride to give α-alkylsulfonyl radicals. 5-Exo-type of intramolecular cyclizations of these radicals are studied. The cyclization is most successful when the olefin is terminally substituted with an ester group. The cis/trans ratio of the cyclized product varies according to the reaction rates. With a faster cyclization, cis-isomer is the major product. A slower cyclization gives more trans-product.