1,3-Dipolar Cycloaddition of Nitrones with Alkenes in Ionic Liquids

摘要

The first intermolecular 1,3-dipolar cycloaddition of nitrones with alkene in ionic liquids is described.The ionic liquids were found to be effective media for the cycloaddition of dibenzylsubstituted nitrone 1 and chiral sugar derived nitrones 7a and 7b with 3-acrylo-yl-1,3-oxazolidin-2-one(2).Excellent chemical yields(61-100%)and moderate dia-stereoselectivities can be achieved in imidazolium ionic solvents at room temperature.The cycloaddition in ionic liquid is completely regioselective in the absence or presence of Lewis acid with only the sterically favoured isoxazolidines 3,4 and 8a,b-11a,b being formed.