Sequential metal-catalyzed N-heteroarylation and C-C cross-coupling reactions: An expedient route to tris(hetero)aryl systems

This paper describes copper-catalyzed N-C heteroarylation of benzimidazole, 1-methylbenzimidazolone, imidazole and pyrrole. The products of these reactions then undergo palladium-catalyzed C-C cross-couplings with aryl or heteroaryl-boronic acids under Suzuki-Miyaura conditions to provide a rapid entry, from readily-available reagents, into tris(hetero)-aryl scaffolds comprising two or three N-heterocyclic rings. The sequential N-C and C-C couplings can be performed in a one-pot process (two examples are given: > 50% overall yields). ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).