Intramolecular cycloadditions isoxazoline ring cleavage

Intramolecular Cycloadditions with Ensuing Ring Cleavage of Intermediate Isoxazolines... 

In the great major tiy of applications that use the intramolecular nitrile oxide-alkene cycloaddition, the intention is to prepare intermediates for the synthesis of natural products or related compounds. The most popular transformations of these isoxazolines are the following ring cleavage modes ... 

Oxidative cleavage of the isoxazoline ring in perhydropyrrolo[l,2-f)]isoxazole (146) with m-chloroperbenzoic acid gives (148) as the sole identifiable product in 79% yield, probably via the nitrone (147) which overcomes the normal predilection for 6-membered ring closure, in intramolecular cycloadditions of nitrones, to afford the adduct <84JA7979, 85T3447). 

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