Stereoselective synthesis and process for the manufacturing of 2′-deoxynucleosides

Methods for stereoselective synthesis and manufacturing of 2′-deoxynucleosides, such as 2′-ribonucleosides, are disclosed. In some embodiments, the 2′-deoxynucleoside is a β-anomer of a 2′-deoxynucleoside having a 3′ α hydroxyl, 4′ β hydroxymethyl configuration. Nonlimiting examples of compounds prepared by the disclosed methods include 4′-thio-2′-deoxycytidine (T-dCyd) and 5-aza-4′-thio-2′-deoxycytidine (5-aza-T-dCyd; aza-T-dCyd; aza-T-dC).