One-Pot Synthesis of Isoxazolines from Aldehydes Catalyzed by Iodobenzene

A convenient one-pot, three-step procedure for the synthesis of isoxazolines starting from aldehydes has been developed involving catalytic cycloaddition between nitrile oxides and alkenes, in which iodobenzene is used as the catalyst for the in situ generation of a hypervalent iodine intermediate. In this approach, the aldehydes are first transformed with hydroxylamine sulfate into aldoximes, which are then oxidized to nitrile oxides by the in situ generated hypervalent iodine intermediate; finally, a 1,3-dipolar cycloaddition between the nitrile oxides and alkenes occurs to provide the isoxazolines in moderate to good yields.