Microwave-induced Bismuth Nitrate-catalyzed Efficient One-pot Synthesis of Pyrroles and their Michael Adducts

Pyrroles are nitrogen-containing heterocycles of significant pharmaceutical and biological relevance. In response to the growing need for greener and efficient synthetic strategies, we report a microwave-assisted, one-pot synthesis of N-substituted pyrroles catalyzed by bismuth nitrate. Utilizing 2,5-dimethoxytetrahydrofuran and various primary amines, the reaction follows a modified Clauson–Kaas pathway under solvent-free conditions. The methodology is further extended by introducing α,β-unsaturated carbonyl compounds into the reaction system, enabling a tandem Michael addition in a single operation. This dual transformation proceeds rapidly under microwave irradiation, affording 2-substituted pyrrole-derivatives in good to excellent yields. The protocol highlights the synergy between microwave activation and bismuth nitrate catalysis, offering a sustainable and efficient route to structurally diverse pyrroles with potential applications in medicinal and materials chemistry.