Metal- and additive-free β-C(sp 2 )-H decarboxylative alkylsulfonylation of enamides from phenyliodine(III) dicarboxylates and sulfur dioxide.

A green process for the direct C(sp 2 )-H decarboxylative alkylsulfonylation of enamides under metal- and additive-free conditions is reported. This reaction employs phenyliodine(III) dicarboxylates as the alkyl radical precursors and DABCO·(SO 2 ) 2 as the sulfur dioxide surrogate. Diverse ( E )-alkylsulfonyl enamides are generated in moderate to good yields with high stereoselectivity under extremely mild conditions via a radical process. A broad substrate scope and excellent functional group tolerance are presented. Moreover, a cascade alkylsulfonylation/cyclization reaction of N -methacryloyl enamides occurs smoothly, giving rise to various alkylsulfonylated pyrrolidones.