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An iron-catalyzed dearomative spirocyclization of biaryl ynones with sodium metabisulfite and cycloketone oxime esters is developed for the construction of sulfonated spiro[5,5]trienones.

An efficient copper-catalyzed regio- and chemoselective multicomponent reaction of 1,6-enynes, diselenides, DABCO·(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.

A photoinduced sulfonylvinylation of unactivated C(sp3)–H bonds through a three-component reaction of propargyl alcohols, potassium metabisulfite and cycloketone oxime esters is developed. This approach enables rapid access to cyanoalkylated vinyl sulfones in moderate to good yields at room temperature under transition-metal-free and external base-free conditions with the formation of three new C–SO2 and C–C bonds in one pot. A radical mechanism involving the insertion of sulfur dioxide with a cyanoalkyl radical and vinyl radical-triggered 1,5-hydrogen atom transfer and functional group migration sequence is proposed.