A synthesis of 9-(2,3-dideoxy-2-fluoro-beta-D-threo-pentofuranosyl)adenine (1, FddA) via a 6-chloro-9-(3-deoxy-beta-D-erythro-pentofuranosyl)-9H-purine (9), which was readily obtained from inosine (5), is described. Fluorination at the C2'-beta position of the purine 3'-deoxynucleoside with diethylaminosulfur trifluoride was improved by the introduction of a 6-chloro group and proceeded in moderate yield. Purine 3'-deoxynucleoside derivatives were also subjected to nucleophilic reactions with triethylamine trihydrofluoride and gave the desired fluorinated nucleoside in good yield. The safety and yield of the fluorination process were greatly improved by the use of triethylamine trihydrofluoride. The influence of the sugar ring conformation and 6-chloro group on the rate of the nucleophilic reaction against elimination are also discussed.

中文翻译：

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经由嘌呤3'-脱氧核苷合成9-（2,3-二脱氧-2-氟-β-D-苏-戊呋喃糖基）腺嘌呤（FddA）。

9-（2,3-二脱氧-2-氟-β-D-苏-戊呋喃糖基）腺嘌呤（1，FddA）的合成是通过6-氯-9-（3-脱氧-β-D-赤-戊呋喃糖基）描述了易于从肌苷（5）获得的）-9H-嘌呤（9）。通过引入6-氯基团可以改善嘌呤3'-脱氧核苷的C2'-β位置与三氟二乙基氨基硫的氟化作用，并且产率中等。嘌呤3'-脱氧核苷衍生物也与三乙胺三氟化氢进行亲核反应，并以高收率得到所需的氟化核苷。通过使用三乙胺三氟化氢大大提高了氟化工艺的安全性和产率。