7‐Deazapurine (pyrrolo[2,3‐d]pyrimidine) nucleosides are important analogues of biogenic purine nucleosides with diverse biological activities. Replacement of the N7 atom with a carbon atom makes the five‐membered ring more electron rich and brings a possibility of attaching additional substituents at the C7 position. This often leads to derivatives with increased base‐pairing in DNA or RNA or better binding to enzymes. Several types of 7‐deazapurine nucleosides with potent cytostatic or cytotoxic effects have been identified. The most promising are 7‐hetaryl‐7‐deazaadenosines, which are activated in cancer cells by phosphorylation and get incorporated both to RNA (causing inhibition of proteosynthesis) and to DNA (causing DNA damage). Mechanism of action of other types of cytostatic nucleosides, 6‐hetaryl‐7‐deazapurine and thieno‐fused deazapurine ribonucleosides, is not yet known. Many 7‐deazaadenosine derivatives are potent inhibitors of adenosine kinases. Many types of sugar‐modified derivatives of 7‐deazapurine nucleosides are also strong antivirals. Most important are 2′‐C‐methylribo‐ or 2′‐C‐methyl‐2′‐fluororibonucleosides with anti‐HCV activities (several compounds underwent clinical trials). Some underexplored areas of potential interest are also outlined.

中文翻译：

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吡咯并[2,3-d]嘧啶（7-脱氮嘌呤）作为抗肿瘤和抗病毒核苷设计中的特殊支架。


7-脱氮嘌呤（吡咯并[2,3- d ]嘧啶）核苷是生物源嘌呤核苷的重要类似物，具有多种生物活性。用碳原子取代 N7 原子使五元环更富电子，并带来在 C7 位置连接额外取代基的可能性。这通常会导致衍生物的 DNA 或 RNA 碱基配对增加或与酶的结合更好。已鉴定出几种具有有效细胞抑制或细胞毒性作用的 7-脱氮嘌呤核苷。最有前途的是 7-杂芳基-7-脱氮腺苷，它在癌细胞中通过磷酸化被激活，并掺入 RNA（导致蛋白质合成抑制）和 DNA（导致 DNA 损伤）中。其他类型的细胞抑制核苷（6-杂芳基-7-脱氮嘌呤和噻吩并稠合脱氮嘌呤核糖核苷）的作用机制尚不清楚。许多 7-脱氮腺苷衍生物是腺苷激酶的有效抑制剂。许多类型的 7-脱氮嘌呤核苷糖修饰衍生物也是强效抗病毒药物。最重要的是具有抗 HCV 活性的 2′- C-甲基核糖或 2′ -C-甲基-2′-氟核糖核苷（几种化合物进行了临床试验）。还概述了一些尚未开发的潜在兴趣领域。