Novel approach to diastereoselective synthesis of 2′‐deoxy[5′‐2H1]ribonucleoside derivatives by reduction of the corresponding 5′‐O‐acetyl‐2′‐deoxy‐5′‐phenylselenoribonucleoside derivatives with a Bu3Sn2H‐Et3B system

Diastereoselective syntheses of [5′-2H]thymidine (6-T) [(5′R)/(5′S) = 31:69], N4-benzoyl-2′-deoxy[5′-2H]cytidine (6-CBz) [(5′R)/(5′S) = 27:76], N6-benzoyl-2′-deoxy[5′-2H]adenosine (6-ABz [(5′R)/(5′S) = 39:61], and 2′-deoxy-N2-isobutyryl[5′-2H]guanosine (6-GiBu) [(5′R)/(5′S) = 20:80] were attained by a radical reductive deuteration reaction of the corresponding 5′-O-acetyl-3′-O-TBDMS-2′-deoxy-5′-phenylselenoribonucleosides (4) with a Bu3Sn2H-Et3B system at <−70°C to give 5 (87–98% yields), followed by unmasking (66–79% yields); 4 were synthesized in three steps of reactions from the corresponding 2′-deoxy-3′-O-TBDMS-5′-O-Ms-ribonucleosides (1) (88–93% yields) by a known method. Chirality 9:435–442, 1997. © 1997 Wiley-Liss, Inc.