Ácido Nióbico como Catalisador Heterogêneo Reciclável na Síntese de Benzimidazóis Substituídos em Meio Livre de Solvente

Abstract

In this work, it was developed a new, simple and convenient procedure for the green synthesis of differently substituted benzimidazoles 3 and 4 using niobic acid (Nb2O5.nH2O) as heterogeneous catalyst and under solvent-free conditions (Scheme 1). After determining the best reaction conditions, we apply this protocol to different aromatic and aliphatic aldehydes 2 were condensed with ophenylenediamine 1 furnishing the corresponding products in moderate to good isolated yields and short reaction times. The reuse of the heterogeneous catalyst was performed by four cycles providing the respective products in satisfactory yields but with a little decreasing in the selectivity.