ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Nitroarenes as versatile building blocks for the synthesis of unsymmetrical urea derivatives and N-Arylmethyl-2-substituted benzimidazoles

Paula A. Rodríguez-Huerto, Diana Peña-Solórzano, and Cristian Ochoa-Puentes

Laboratorio de Síntesis Orgánica Sostenible, Departamento de Química, Universidad Nacional de Colombia–Sede Bogotá, Bogotá, Colombia

E-mail: cochoapu@unal.edu.co

Received: 29 March 2021  Accepted: 6 July 2021

Abstract:

In this contribution, a fast and simple method for the synthesis of unsymmetrical urea derivatives and N-arylmethyl-2-substituted benzimidazoles was developed starting from nitroarenes. The reaction of nitroarenes and phenyl isocyanate or phenyl isothiocyanate in tin (II) chloride dihydrate/choline chloride eutectic mixture afforded the expected urea and thiourea derivatives, while the reaction of different aldehydes with o-nitroaniline or 4-methoxy-2-nitroaniline shows a markedly high preference for the obtention of N-arylmethyl-2-substituted benzimidazoles over the 2-substituted analogues. This method offers a straightforward alternative to obtain the target compounds in good to excellent yields with short reaction times employing an operationally simple experimental set-up.

Graphic abstract

A series of unsymmetrical urea and thiourea derivatives together with 1,2-disubstituted benzimidazoles are easily obtained in good yields starting from nitroarenes employing the eutectic mixture tin (II) chloride dihydrate/choline chloride as reductive reaction media.

Keywords: Benzimidazoles; Deep eutectic solvents; Nitroarenes; Redox solvent; Urea derivatives

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-01785-7

Chemical Papers 75 (12) 6275–6283 (2021)