Isoxazole, by cycloadditions

These experimental facts indicate that it is possible to synthesize differently bis-fimctionalized isoxazoles by cycloaddition of 6 with P-keto esters 34 direcdy. Among the numerous studies on nitrile oxides, only those examples in which a 1,3-dicarbonyl compound is employed as a dipolar-ophile are found in the literature (Scheme 9.14). Umesha et al. prepared 4-acetyl-3-arylisoxazoles by the cycloaddition of isolable aromatic nitrile oxides with acetylacetone 34b [59]. Suzuki and coworkers developed the cyclocondensation of hindered aromatic nitrile oxides with cyclic P-diketones, which was applied to the synthesis of natural products [60]. In these reactions, nitrile oxide was stable enough for isolation thus, a substituent at the 3-position of the cycloadducts was limited to an aromatic group. 

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See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

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