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Chiral isoxazole and carbocyclic pyrimidine nucleoside analogues were synthesized by way of (3+2)-cycloadditions of chiral pyrimidinyl-substituted dimethyl cyclopropanedicarboxylates. In the existence of MgI 2 , (3+2)-cycloadditions of chiral pyrimidinyl-substituted cyclopropanes with nitrosoarenes afforded numerous chiral isoxazole pyrimidine nucleoside analogues in up to 78% yield and 88-96% ee. Working with Nd(OTf) 3 as the catalyst, the annulation reaction with silyl enol ethers produced a collection of chiral carbocyclic pyrimidine nucleoside analogues in up to 64% produce, >20:1 dr, and 87-96% ee. The proposed techniques possibly reduced or prevented partial racemization.
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