Synthesis of Highly Substituted 1,2,4-Triazole-Based 3-Nitrochromanes through Aza-Michael Addition Reaction under Catalyst- and Base-Free Conditions

Abstract A simple and efficient aza-Michael addition reaction of 1,2,4-triazoles to functionalized 2-aryl-3-nitro-2H-chromenes has been demonstrated under catalyst- and base-free conditions. In this transformation, one intermolecular C–N bond formation is achieved at room temperature. A series of highly substituted 1,2,4-triazole-based 3-nitrochromanes were produced in good to excellent yields, up to 86%. The relative configuration of the Michael adducts was confirmed by X-ray crystallographic analysis. High yield, easy accessibility and a wide variety of functional group tolerance are the key features of this aza-Michael­ addition reaction.