Synthesis of 1H,7H,12bH-Pyrano[3′,4′:5,6]pyrano[3,4-c][1] benzopyran-1-one via domino Knoevenagel/hetero-diels-alder reaction with theoretical investigations

摘要

The CuI-catalyzed intramolecular oxa-Dielsi-Alder reaction of 2-(prop-2-yn-1-yloxy)benzaldehydes as unactivated terminal alkynes with 4-hydroxy-6-methyl-2H-pyran-2-one is described. The reaction proceeds with remarkable chemoselectivity to yield pyranones 3 (Scheme1). A theoretical investigation of the reaction in terms of HOMOi-LUMO interactions in the gas phase is also reported. The reaction could be regarded as an inverse-electron-demand Dielsi-Alder cycloaddition. The theoretical results are in high agreement with the experimental evidences.