Stereoselective Approach for the Synthesis of Diverse 1'-Modified Carbanucleosides.

We describe an efficient and stereoselective synthesis of 1'-substituted-β-carbocylic nucleosides 5 via gem -dichlorooxirane intermediate 7 , which directly condensed with weak nucleophiles such as pyrimidines or purines. The formation of gem -dichlorooxirane 7 and direct nucleobase condensation exclusively proceeded in protic polar solvents like MeOH. This method provides a general and modular route for the late-stage diversification of 1'-modified nucleosides.