Copper-catalyzed synthesis of sulfonamides from nitroarenes via the insertion of sulfur dioxide

Abstract

Nitroarenes are used as the coupling partners in the preparation of sulfonamides via the insertion of sulfur dioxide. A three-component reaction of arylboronic acids, nitroarenes, and potassium metabisulfite under copper catalysis proceeds smoothly, giving rise to a range of sulfonamides in good to excellent yields with broad substrate scope. Various functional groups including hydroxyl, cyano, amino, and carbonyl are all tolerated. A plausible mechanism is proposed, showing that arylsulfinate is the intermediate and the copper-assisted interaction of the nitroarene and arylsulfinate is the key step. This approach is also extended to the late-stage modification of a currently marketed drug (flutamide).