Visible-light promoted cascade cyanoalkylsulfonylation/ ipso -cyclization of N -arylpropiolamides toward sulfonated spiro[4,5]trienones via SO 2 insertion.

A novel visible-light induced sulfonylation/ ipso -cyclization of N -arylpropiolamides with cyclobutanone oxime esters and Na 2 S 2 O 5 was reported. This protocol proceeded via a radical process. The wide substrate scope, sustainable metal-free conditions and readily accessible reagents make this protocol an efficient and green strategy for the synthesis of cyanoalkyl sulfonated spiro[4,5]trienones.