Lewis Acid Catalyzed (3+2)‐Cycloadditions of Chiral Pyrimidinyl‐Substituted Cyclopropanes with Nitrosoarenes or Silyl Enol Ethers

Abstract

AbstractChiral isoxazole and carbocyclic pyrimidine nucleoside analogues were synthesized via (3+2)‐cycloadditions of chiral pyrimidinyl‐substituted dimethyl cyclopropanedicarboxylates. In the presence of MgI2, (3+2)‐cycloadditions of chiral pyrimidinyl‐substituted cyclopropanes with nitrosoarenes afforded diverse chiral isoxazole pyrimidine nucleoside analogues in up to 78 % yield and 88–96 % ee. Using Nd(OTf)3 as the catalyst, the annulation reaction with silyl enol ethers generated a series of chiral carbocyclic pyrimidine nucleoside analogues in up to 64 % yield, >20 : 1 dr, and 87–96 % ee. The proposed methods either reduced or avoided partial racemization.