A new route to 2′,3′‐dideoxycytidine

Abstract 2‐Deoxy‐D‐ribose ( 1 ) was converted into its methyl glycofuranoside 2 , which was treated with 4‐biphenylcarbonyl chloride to give a separable mixture of 3 (26%) and 4 (40%). Compounds 3 and 4 were deoxygenated by Barton deoxygenation to give the corresponding 2,3‐dideoxyribose derivatives 7 and 8 in good yields as crystalline materials. Reaction of 7 and 8 with the silylated N 4 ‐isobutyrylcytosine 9 , using trimethylsilyl triflate as catalyst afforded a separable mixture of the protected 2′,3′‐dideoxynucleosides 10 (29%) and 11 (31%) which were deprotected with methanolic ammonia to give 2′,3′‐dideoxycytidine ( 12 ) and its α‐anomer 13 .