Homolytic Displacement at Saturated Carbon. 9. The Reactions of Trichloromethanesulfonyl Chloride with Pent-4-enylcobaloximes and with Olefines. A Novel Route to (Trichloroethyl)sulfolanes via an SHi Mechanism

Article abstract of DOI:10.1021/jo00184a017

Pent-4-enylcobaloximes react with trichloromethanesulfonyl chloride in inert solvents under irradiation with tungsten lamps to give good yields of 2-(β,β,β-trichloroethyl)sulfolanes.The same products are formed in the thermal reactions in the presence of an excess of sulfur dioxide.Studies of the reactions of related olefins with trichloromethanesulfonyl chloride catalyzed by the photolysis of secondary organocobaloximes under mild conditions show that substituted 3,3,3-trichloropropyl radicals are capable of capturing sulfur dioxide.This allows us to account for the formation of the sulfolanes by a mechanism which includes a homolytic displacement of cobaloxime(II) from saturated carbon.The latter is confirmed by the observation that the isomers of 2-methyl-5-(β,β,β-trichloroethyl)sulfolane formed from (R)-hex-5-en-2-ylcobaloxime are in substantial enantiomeric excess. 3-Chloro-1,1-dioxothiacyclohexanes formed as minor products indicate that pent-4-ene-1-sulfonyl radicals cyclize to 1,1-dioxothiacyclohex-3-yl radicals rather than to the corresponding five-membered sulfolanylmethyl radicals.