Cascade Synthesis of N-Heterocyclic Compounds through One-Pot MCR over Cu<sup>II</sup>−Hydrotalcite Catalyst

Abstract

This article highlights the cascade synthesis of various N-heterocycles and C–N bonding organic transformations catalyzed by a simple and efficient heterogeneous CuII–hydrotalcite (CuII–HT) catalyst. The CuII–HT was found to be a dynamic catalyst and exhibited promising catalytic activity towards one-pot MCRs, namely, synthesis of 1,4- disubstituted 1,2,3-triazoles, synthesis of 2H-indazoles, and C–N bond forming reactions. These protocols are credited with several advantages such as readily available starting materials, simple workup procedure, better yields, shorter reaction times, and broader substrate scope. The in-situ generated organic azide (R–N3) and heterocyclization (C–N and N–N bond formation) are the key steps to deliver the desired 1,4-disubstituted 1,2,3-triazoles and 2H-indazoles, respectively. Keywords: CuII–Hydrotalcite, N-Heterocycles, C–N Bond Formation, Heterogeneous Catalysis, 1, 2, 3-Triazoles, 2H-Indazoles.