C−H/C−H oxidative coupling has emerged as a straightforward and powerful technique for the construction of (hetero)biaryls, with substantial application to drug discovery, agrochemicals, biology, and material sciences. Mainly aryl‐aryl, aryl‐heteroaryl, and heteroaryl‐heteroaryl couplings via double C(sp2)−H activation using 4d or 5d noble transition metal catalysts have been extensively studied. Considering the earth‐abundant and inexpensive nature of 3d transition metals, the sustainable development of C(sp2)−H/C(sp2)−H oxidative coupling employing such metal catalysts has gained significant attention. In this review, we present a comprehensive overview of C(sp2)−H/C(sp2)−H oxidative coupling of (hetero)arenes catalyzed by 3d transition metals.

Chemodivergent (de)hydrogenative coupling of azoarenes with benzyl alcohols is achieved via the N=N bond activation using an inexpensive and well-defined (6-OH-bpy)NiCl2 catalyst. This protocol highlights the construction of C–N bonds...