Cu–Catalyzed Expeditious Synthesis of N-Benzylaminoheter-ocycles Using N-Tosylhydrazones and Aminoheteroarenes

Abstract

N-Tosylhydrazones were successfully coupled in the presence of CuI (10 mol%) with various heterocyclic amines to develop a convenient and high yielding protocol for the preparation of N-benzylaminoheterocycles under microwave irradiation. This ligand-free new methodology uses readily available starting materials and a cheaper copper catalyst. A wide range of O, N and S containing heteroarylamines and o-phenylenediamine were explored to prepare N-benzylaminoheterocycles and 1,2-disubstituted benzimidazoles. The protocol was equally effective with N-tosylhydrazones derived from aldehydes and ketones, especially ferrocene aldehyde to prepare an array of N-benzylaminoheterocycles in good to excellent yields. Finally, the identified reaction conditions were utilized to prepare drug-like molecules namely pyrido[1,2-a]benzimidazole and N-substituted-2-amino-thiazole derivative as antitubercular agents.