Copper-catalyzed synthesis of 2-aminobenzimidazoles from carbonimidoyl dichlorides and amines

Silver-Catalyzed and Base-Mediated Double Cyclization for the Streamlined Synthesis of Benzo[4,5]imidazo[2,1-b]naphtho[2,3-d]oxazole from ortho-Alkynylarylketones

We report a novel silver-catalyzed and base-mediated double cyclization strategy for the streamlined synthesis of benzo[4,5]imidazo[2,1-b]naphtho[2,3-d]oxazoles from ortho-alkynylarylketones. The transformation proceeds through an initial ketonization step catalyzed by silver trifluoroacetate (AgTFA), generating a reactive 1,5-diketone intermediate, followed by a sequential double cyclization under basic conditions. This method affords a broad range of benzo[4,5]imidazo[2,1-b]naphtho[2,3-d]oxazoles with good functional group tolerance in moderate-to-good yields. Moreover, this methodology also enhances the synthetic utility of ortho-alkynylarylketones, expanding their applicability in constructing diverse fused heterocycles.

Copper-Catalyzed Coupling between ortho-Haloanilines and Lactams/Amides: Synthesis of Benzimidazoles and Telmisartan

An efficient copper-catalyzed synthesis of (annelated) benzimidazoles is reported. This transformation is based on a simple and straightforward one-pot sequence involving a copper-catalyzed cross coupling between o-haloanilines and lactams/amides followed by a subsequent cyclization under acidic conditions. A variety of (annelated) benzimidazoles could be easily obtained in high yields from readily available starting materials, and this procedure could be further applied to the synthesis of the antihypertensive blockbuster drug telmisartan.

Cascade palladium catalysis: a predictable and selectable regiocontrolled synthesis of N-arylbenzimidazoles

By choice: The palladium-catalyzed cascade reaction of 2-chloroaryl sulfonates with arylamine and amide nucleophiles provides direct access to N-arylbenzimidazoles. This strategy selectively produces the heterocycles based on chemoselective oxidative addition. 2-Chloroaryl triflates (Tf) produce one regioisomer and the corresponding 2-chloroaryl mesylates (Ms) deliver the other in a selectable manner.