Synthesis of 4-Substituted 3, 5-Bis(methoxycarbonyl)-2-isoxazoline 2-Oxides

Abstract

4-Substituted 3, 5-bis(methoxycarbony1)-2-isoxazoline 2-oxides, cyclic nitronic esters of type [I], have been readily synthesized in reasonable yields by an one-pot reaction of aldehydes with two molar amount of methyl nitroacetate in the presence of diethylamine in a polar aprotic solvent such as N, N-dimethylacetamide (DMA).4-Substituent of [I] comprises o-, m, or p-functionalized phenyl, fused aryl, or heteroaromatic group. Yields and physical properties of newly prepared 2-isoxazoline 2-o, xides, are, summarized in Table 1, while their spectroscopic data are given in Table 2 (IR, UV, MS, and 1H-NMR)as well as Table 3(13C-NMR). This method is found to be widely applicable to the synthesis of such 2-isoxazoline 2-oxides as type [I], which may serve as an useful intermediate for the synthesis of new type of heterocycles through the ring transformation as reported previously by the authors.