Visible-light-induced remote C(sp3)–H sulfonylvinylation: assembly of cyanoalkylated vinyl sulfones

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.