Facile synthesis of oxabicyclic alkenes by ultrasonication-promoted diels-alder cycloaddition of furano dienes.

Ultrasonic irradiation effectively promotes the Diels-Alder reaction of substituted furans with reactive dienophiles (i.e., dimethyl acetylenedicarboxylate (DMAD) and dimethyl maleate). Regiospecific furano Diels-Alder cycloaddition of 2-vinylic furans with DMAD furnished functionalized oxabicyclic alkenes in good yield under ultrasonication condition.