Organocatalytic Domino Knoevenagel Hetero-Diels-Alder Reaction for the Synthesis of Chromenopyran Derivatives

Abstract:: An organocatalytic, one-pot four-center two-component coupling reaction has been developed for the synthesis of tetrahydro-1H,7H-chromeno[3,4-c]chromen-1-one derivatives. The reaction proceeds smoothly in the presence of 5 mol% DL-Proline in methanol under reflux conditions. This method involves the Knoevenagel condensation of O-alkynyl tethered 2-hydroxybenzaldehydes with cyclic 1,3-diketones followed by an intramolecular hetero-Diels-Alder reaction. Novel classes of oxygen containing polycyclic frameworks are prepared in good yields by using this approach.