Chiral isoxazole and carbocyclic pyrimidine nucleoside analogues were synthesized by (3+2)-cycloadditions of chiral pyrimidinyl-substituted dimethyl cyclopropanedicarboxylates. With MgI₂ or Nd(OTf)₃ as the catalysts, diverse chiral pyrimidine nucleoside analogues were obtained in 87–96 % ee. The proposed methods either reduced or avoided partial racemization.

中文翻译：

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手性嘧啶基取代的环丙烷与亚硝基芳烃或甲硅烷基烯醇醚的路易斯酸催化 (3+2)-环加成反应

通过手性嘧啶基取代的环丙烷二羧酸二甲酯的 (3+2)-环加成反应合成手性异恶唑和碳环嘧啶核苷类似物。以 MgI ₂或 Nd(OTf) ₃作为催化剂，获得了 87-96% ee 的多种手性嘧啶核苷类似物。所提出的方法减少或避免了部分外消旋化。