Electrochemical Sequential Cross-Dehydrogenative Coupling for the Chemoselective Synthesis of Bis(arylthio)-Substituted Biphenyl Diamines

Abstract

Controlling C–C and C–S bond formation in one oxidative operation remains challenging because the two coupling modes compete and thiols are prone to overoxidation. Herein, we report an oxidant- and transition-metal-catalyst-free electrochemical strategy for synthesizing symmetric 3,3′-bis(arylthio)-4,4′-biphenylenediamines through current-controlled stepwise radical cross-dehydrogenative coupling. Guided by differences in oxidation potentials, optimized current and acetic acid enable sequential C(sp2)–H/C(sp2)–H and C(sp2)–H/S–H coupling in one pot. To the best of our knowledge, this represents a rare example of chemoselective electrochemical construction of C–C and C–S bonds from anilines and thiophenols. The protocol suppresses thiol overoxidation, shows broad functional group tolerance (up to 96% yield) and gram-scale feasibility (1.9 g), and delivers bithioether diamines useful as functional organosulfur materials and polymer monomer precursors.