Ethanol → 2'-Azido-2'-deoxycytidine

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Reaction Steps

1 g. 2'-Azido-2'-desoxy-3',5'-diacetyl-uridine (see J. Hobbs, H. Sternbach, M. Sprinzl and F. Eckstein, Biochemistry, 12, 5138/1973) was mixed with 14 ml. ethanol-free chloroform and 0.14 ml. dimethyl formamide and then mixed with 2 ml. thionyl chloride. The reaction mixture was boiled under reflux, with the exclusion of moisture, for 6 hours. After cooling, the reaction mixture was evaporated in a vacuum and the residue treated with ammoniacal methanol (30 ml. dry methanol plus 30 ml. methanol saturated with ammonia). The solution was stirred for 2 days at ambient temperature and then left to stand for 2 days at 37° C. Thin layer chromatography (methanol/chloroform mixture (4/6 v/v) on silica gel plates, Herck 60 F 254) shows mainly a product with an Rf value of 0.62. The solution was evaporated, the residue applied to two plates coated with silica gel for preparative thin layer chromatography (Merck 60 F 254, 2 mm. layer thickness, 20×40 cm.) and developed with a chloroform/methanol mixture (6/4 v/v). The main bands were scraped off, the material was eluted with methanol and applied to an ion exchanger column (Dowex 1×2, OH, 1.7×21.5 cm.). After washing with water, the product was eluted with 30% aqueous methanol. The solution obtained was evaporated and the residue recrystallized from ethanol. 2'-Azido-2'-desoxycytidine was obtained in a yield of 12310 A270 units (1.32 mMol; 47% of theory). The product melts at 215° C.

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