Ultrasound Promoted 1, 3-Dipolar Cycloaddition Reactions of Nitrile Oxides with α, β-Unsaturated Acetals

The 1,3-dipolar cycloaddition reactions of nitrile oxides and α,β-unsaturated 1,3-dioxolanes were effectively accelerated by ultrasound irradiation to give the A²-isoxazolines with yields and regioselectivities surpassing those of the corresponding thermal reactions.