Aqua Mediated One-Pot Synthesis of 2-Amino-tetrahydrobenzo[b]pyran Derivatives Catalyzed by Mg(NO3)2•6H2O

We describe herein a clean and efficient one-pot synthesis of 4H-benzo[b]pyran derivatives using dimedone, active methylene nitriles and aryl aldehyde via Knoevenagel condensation followed by Michael addition in the presence of Mg(NO3)2•6H2O as catalyst and water as a green solvent. The advantages of this method lie in its simplicity, low catalyst loading, cost effectiveness and easy handling. The present method also allows us to synthesize highly functionalized tetrahydrobenzo[b]pyran derivatives from simple and readily available starting materials.