Ag-Mediated Sulfonyl-Alkenylation of Unactivated Alkynes via Intramolecular C(sp2)-H Cyclization toward 1,2-Dihydropyridines.

1,2-Dihydropyridines and sulfonyl compounds are widely found in bioactive molecules and functional materials. Herein, a silver-mediated radical sulfonyl-alkenylation of vinylamino-linked alkynes with sodium sulfinates via intramolecular C(sp2)-H cyclization for producing sulfonylated 1,2-dihydropyridines in a highly selective manner was developed. The two-component alkyne sulfonyl-alkenylation enables the construction of two new bonds, including a C(sp2)-S bond and a C(sp2)-C(sp2) bond, through the sulfonyl radical formation, selective radical across the alkyne moiety and alkenylation cascades, and represents an efficient route to preparing a series of sulfonylated 1,2-dihydropyridines with up to 98% yields with high regioselectivities and good functional group tolerance.