Synthesis of 2H ,4H ,9bH - Furo[3,2-c][1]benzopyrans by a new intramolecular cycloaddition of a carbonyl ylide to an acetylene

Article abstract of DOI:10.1016/S0040-4020(01)88295-8

Thermal treatment of oxiranes 1 and 4 affords 2H, 4H, 9H-furo[3,2-c][1]benzopyrans 5 and 6 through an intra-molecular 1,3-dipolar cycloaddition between the carbonyl ylide, generated by ring opening of the oxirane, and the acetylene moiety.