One-pot synthesis of dimerized arenes and heteroarenes under mild conditions using Co(I) as an active catalyst

A feasible one-pot synthesis of dimerized arene and heteroarene systems was achieved by employing 2 mol% of Co(II)catalyst 1 along with Zn dust at room temperature in 2-4 h. The Co(II)/Zn(0) system in situ generates Co(I) as an active catalyst. This catalyst can effectively substitute expensive Pd catalysts and hygroscopic and air-sensitive ZnCl₂, generally employed to generate such dimerized heterocyclic cores. Pd is replaced with the Co core and anhydrous ZnCl₂ is replaced with easy-to-handle and highly economical Zn dust in its activated form. While conventional methods use high temperature and/or longer reaction times, our synthetic strategy achieves the desired goal with high % yields of products (70-89%) at room temperature in a moderate reaction time (2-4 h), replacing expensive reagents at the same time. The Co(II) catalyst, 1, is easy to synthesize, economically viable, thermally stable, and insensitive to air or moisture. The catalyst has been well characterized by EPR, IR, CV and UV-vis spectroscopy and EDX studies.