SPIROHETEROCYCLES FROM REACTION OF NITRILE OXIDES WITH 3-METHYLENEPHTHALIMIDINES

In explorations of syntheses and chemistry of spiroheterocycles, we found that reaction of aromatic nitrile oxides with 3-methylenephthalimidines 8 produced spiroheterocycles 9. When N-benzyl-3-methylenephthalimidine (8c) was employed, oximes 10 and 11 were formed in addition to the spiroheterocycles. Solvent effects on the reaction rates and on product ratios indicate that the product mixtures result from competition between a 1,3-cycloaddition reaction of nitrile oxide with 8 to produce a spiroheterocycle and a diradical reaction of nitrile oxide with 8 to produce the oximes. Spiroheterocycles 9b and 9f were converted cleanly to 2-(3-phenyl-5-isoxazolyl)benzanilide 12a and benzamide 12b, respectively, with base catalysis. © 1990, American Chemical Society. All rights reserved.