ICYTAC   23898
INSTITUTO DE CIENCIA Y TECNOLOGIA DE ALIMENTOS CORDOBA
Unidad Ejecutora - UE
artículos
Título:
Selective and eco-friendly procedures for the synthesis of Benzimidazole derivatives. The role of Er(OTf)3 catalyst in the selectivity of the reaction
Autor/es:
MÓNICA NARDI; ANA N SANTIAGO; NATIVIDAD HERREA CANO; A. PROCOPIO; URANGA, J. G.; DANIEL A. WUNDERLIN
Revista:
BEILSTEIN JOURNAL OF ORGANIC CHEMISTRY
Editorial:
BEILSTEIN-INSTITUT
Referencias:
Año: 2016 vol. 12 p. 2410 - 2419
ISSN:
1860-5397
Resumen:
An improved and greener protocol for the synthesis of benzimidazole derivatives, starting from o-phenylenediamine, with different aldehydes is reported. Di-condensation products were selectively obtained when Er(OTf)3 was used as catalyst in presence of electron-rich aldehydes. Conversely, the formation of mono-condensation products was the preferred path in absence of this catalyst. One additional advantage of these reactions was the formation of a single product, avoiding extensive isolation and purification of products, which is frequently found with these reactions. Theoretical calculations helped to understand the different reactivity established for these reactions. Thus, we found that the charge density on the oxygen of the carbonyl group was a significant factor to facilitate the reaction pathway. For instance, electron-rich aldehydes facilitated the coordination of aldehydes to the catalyst, which favoured the addition of the amine group to the carbonyl group, helping with the formation of di-condensation products. Reactions with aliphatic or aromatic aldehydes were possible, without using organic solvents and by a one-pot procedure with short reaction time (2-5 min), affording excellent yields (75-99 %) and a single product. So far, this convenient and eco-friendly methodology offers numerous benefits with respect to different protocols reported for similar compounds.