Solution and solid-phase synthesis of 1-pyrazol-3-ylbenzimidazoles

PORTILLA, J.; QUIROGA, J.; ABONIA, R.; INSUASTY, B.; NOGUERAS, N.; COBO, J.; MATA, E.G.

SYNTHESIS-STUTTGART

Thieme

Lugar: Stuttgart; Año: 2008 p. 387 - 394

0039-7881

We report herein the facile solution and solid-phase synthesis of 1-pyrazol-3-ylbenzimidazoles from 4-fluoro-3-nitrobenzoate derivatives and 5(3)-amino-3(5)-subtituted-1H-pyrazoles. The key step was the unexpected nucleophilic aromatic displacement of the activated fluorine by the exocyclic amino group of the pyrazole ring leading to 4-pyrazolylamino-3-nitrobenzoate derivatives that were easily converted into the corresponding 1-pyrazol-3-ylbenzimidazoles in very high isolated yield. These novel methodologies would be very useful for the generation of libraries of diverse 1-heteroaryl derivatives of benzimidazoles.