A regiospecific synthesis of N9‐alkylated purines as novel acyclic nucleosides was developed. This approach is based on reconstructive methodology involving the construction of a target heterocyclic scaffold on a readily available 5‐aminotetrazole moiety, which is subsequently cleaved under reductive conditions due to azido‐tetrazole tautomerism. It appeared that the rate of reduction for the azide fragment in 6‐nitro‐7‐alkylaminotetrazolo[1,5‐a]pyrimidines is much greater than the rate of nitro group reduction. Treatment of these heterocycles with hydrogen over a palladium catalyst resulted in the formation of triaminopyrimidines in excellent yields through the reduction of both the azide and nitro group. Triaminopyrimidines were transformed into the desired N9‐alkylated purines, and an analog of the marketed drug penciclovir was synthesized by the developed method.

中文翻译：

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N9-烷基化嘌呤区域特异性合成的重建方法


开发了 N9-烷基化嘌呤作为新型无环核苷的区域特异性合成。该方法基于重建方法，涉及在易于获得的 5-氨基四唑部分上构建目标杂环支架，随后由于叠氮基-四唑互变异构现象在还原条件下裂解。 6-硝基-7-烷基氨基四唑并[1,5-a]嘧啶中叠氮化物片段的还原速率似乎远大于硝基还原速率。在钯催化剂上用氢处理这些杂环，通过叠氮基和硝基的还原，以优异的产率形成三氨基嘧啶。将三氨基嘧啶转化为所需的 N9 烷基化嘌呤，并通过开发的方法合成了市售药物喷昔洛韦的类似物。