Sulfur incorporation: copper-catalyzed cascade cyclization of 1,7-enynes with metal sulfides toward thieno[3,4-c]quinolin-4(5H)-ones.

A novel copper-catalyzed cascade cyclization of 1,7-enynes with metal sulfides is described. This sulfur-incorporation method provides straightforward access toward the important thiophene-fused quinolin-4(5H)-one scaffold through cyclization and double C-S bond formation cascade, and the chemoselectivity of this 1,7-enyne cyclization toward 1,3,3a,9b-tetrahydrothieno[3,4-c]quinolin-4(5H)-ones and 3,3a-dihydrothieno[3,4-c]quinolin-4(5H)-ones can be controlled by varying the sulfur resources.