Ruthenium-catalyzed selectively oxidative C-H alkenylation of N-acylated aryl sulfonamides by using molecular oxygen as an oxidant.

A ruthenium-catalyzed sulfonamide-directed ortho aryl C-H alkenylation/annulation to afford five-membered sultam by using of molecular oxygen as an oxidant is reported in this article. Compared to the previous transition-metal-catalyzed C-H alkenylation of aryl sulfonamides, no excess metal salt oxidant was required in this method. A wide sulfonamide substrates scope and good regioselectivity and site-selectivity make this Ru-catalyzed method more attractive. Importantly, this method can not only be used to effectively prepare the biologically active five-membered sultam molecules but also be efficiently applied to the late-stage modification of sulfonamide drugs.