Synthesis of novel biaryl 2-benzimidazoles and 2-benzothiazoles

Herein, we describe the synthesis of the novel 4-(1H-benzo[d]imidazol-2-yl)isoxazol-5-amine (7) and 4-(1H-benzo[d]thiazol-2-yl)isoxazol-5-amine scaffolds (8). Initial attempts following literature procedures for the synthesis of similar compounds did not yield the desired product. Instead we obtained the ring-opened adduct 2-(1H-benzo[d]imidazol-2(3H)-ylidene)-2-cyanoacetamide (5). We were able to modify reaction conditions and successfully synthesize the desired product. We also describe a convenient one-pot microwave-assisted relay reaction for the synthesis of novel and reported 2-substituted benzimidazoles and benzothiazoles from inexpensive, commercially available reagents, 2-benzothiazole acetonitrile (2) and 2-benzimidazole acetonitrile (1). In all cases, good yields of products were obtained and reaction times were significantly reduced.

Graphical abstractHerein, we describe the synthesis of the novel 4-(1H-benzo[d]imidazol-2-yl)isoxazol-5-amine (7) and 4-(1H-benzo[d]thiazol-2-yl)isoxazol-5-amine scaffolds (8). Initial attempts following literature procedures for the synthesis of similar compounds did not yield the desired product. Instead we obtained the ring-opened adduct 2-(1H-benzo[d]imidazol-2(3H)-ylidene)-2-cyanoacetamide (5). We were able to modify reaction conditions and successfully synthesize the desired product. We also describe a convenient one-pot microwave-assisted relay reaction for the synthesis of novel and reported 2-substituted benzimidazoles and benzothiazoles from inexpensive, commercially available reagents, 2-benzothiazole acetonitrile (2) and 2-benzimidazole acetonitrile (1). In all cases, good yields of products were obtained and reaction times were significantly reduced.Download full-size image