Commercial Nickel-catalyzed Cross-coupling of Organolithium Reagents with 2-arylbenzothiazoles

In the Kumada reaction, commercially accessible nickel catalysts facilitate the synthesis of 2-arylbenzothiazoles from various aryllithium compounds and 2-chlorobenzothiazole. This catalytic process is effective irrespective of the presence of electron-withdrawing or electron-donating groups on the benzene ring of aryllithium. Among these zero-valent, divalent nickel, and divalent nickel complexes, divalent nickel complexes have the best catalytic effect. NiCl₂(PCy₃)₂ (Cy = cyclohexyl) has the best catalytic performance. The highest yield of 2-C₆H₄benzopyrazole from C₆H₄Li and 2-chlorobenzopyrazole was 92.1% with the use of an NiCl₂(PCy₃)₂ catalyst. this method eliminates the need for expensive palladium reagents and nickel complexes that require synthesis.