Cycloaddition/Ring Opening Sequence of α-Hydroxy Cyclic Nitronates as a Synthetic Equivalent of Functionalized Aliphatic Nitrile Oxides

α-Hydroxy cyclic nitronates act as synthetic equivalents of nitrile oxides. Cycloaddition of 3-substituted 4-hydroxy-2-isoxazoline N-oxides or 4-hydroxy-3-hydroxymethyl-2-isoxazoline N-oxides with electron-deficient alkenes produce bicyclic isoxazolidines, which undergo ring opening of one of the ring-fused isoxazolidines on acid treatment to give 2-isoxazoline derivatives by elimination of hydroxyacetaldehyde or carbon-carbon bond cleavage.