2-Alkylisoxazolidine-3,3-dicarboxylic acid derivatives

1,3-Dipolar cycloaddition of,-bis(alkoxycarbonyl)-N-alkylnitrones to olefins gave 2-alkylisoxazolidine-3,3-dicarboxylic acid esters, the yields of which are determined by the steric conditions and are virtually independent of the electronic effect of the substituents attached to the C=C bond of the dipolarophiles. The structures of the compounds obtained were established by analysis of the PMR spectra. The retention of the cis configuration of the substituents in the isoxazolidines obtained from maleic acid esters constitutes evidence for a one-step, four-center, concerted cycloaddition mechanism. The energy parameters for inversion of the nitrogen atom of dimethyl 2,5,5-trimethylisoxazolidine-5,5-dicarboxylate were measured.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 599–603, May, 1979.