Copper-catalyzed regio- and chemoselective selenosulfonylation of 1,6-enynes from sulfur dioxide

An efficient copper-catalyzed regio- and chemoselective multicomponent reaction of 1,6-enynes, diselenides, DABCO center dot(SO2)(2) and cycloketone oxime esters is described. Under mild conditions, this protocol exhibits a broad substrate scope and high functional group compatibility, enabling rapid access to cyanoalkylsulfonylated pyrrolidines in moderate to good yields. This radical-triggered cyclization reaction allows the formation of four new bonds including the C-SO2, C-C and C-Se bonds in a single step. A plausible mechanism is proposed on the basis of control experiments, and a cyanoalkylsulfonyl radical species is involved during the reaction process.