Copper-Exchanged Tungstophosphoric Acid: An Efficient and Reusable Heteropoly Acid for the Synthesis of 2,3,4,5-Tetrahydro-4-methylidenefuran Derivatives

摘要

Copper-exchanged tungstophosphoric acid (Cu-TPA) is found to catalyze efficiently the coupling of propargyl alcohol (prop-2-yn-1-ol) with (arylmethylidene) malononitriles to afford the corresponding 2,3,4,5-tetrahydro-4-methylidenefuran derivatives in good yields and with high selectivity. The catalyst is recycled and reused for three-to-four subsequent runs with a minimal decrease of activity.