A series of N4-alkyl-5-azacytidines 3a-3h were prepared by treatment of the 4-methoxy analogue 4 with the respective amines. In the case of propyl-, butyl-, sec-butyl-, benzyl- or furfurylamine, aggregates of azacytidines 3a-3e with their hydrolytic products 5a-5e were isolated. Similar aggregates were obtained with 1-methyl-5-azacytosine (6) and 2-(methylcarbamoyl)guanidine (7). Compound 7 was prepared by the reaction of guanidine with methyl isocyanate; the reaction of 2 or 3 equivalents gave the di- or tricarbamoyl derivatives 11 and 12, respectively. Cyclization of 7 and 11 with DMF dimethyl acetal afforded azacytosines 6 and 13, respectively. Aggregates of guanosine with 5-azacytosine nucleosides 1, 2 and 15 or of 5-aza-5,6-dihydrocytosine nucleosides 16 and 17 with 5-azacytidine (1) and its 2'-deoxy congener 2 have been prepared by co-crystallization of the respective pairs of nucleosides. The anomers of (deoxyribosylcarbamoyl)guanidine 20a and 20b have been prepared by hydrolysis of the deoxy nucleoside 2. An aggregate of the picrate (8a) of (ribosylcarbamoyl)guanidine 8 with cytidine (9) has been obtained by co-crystallization of both components. Reaction of the methoxy nucleoside 4 with tert-butylamine gave, by contrast to the above mentioned amines, the α-anomer of O-methylribosylisobiuret 22, which was cyclized by DMF dimethyl acetal to the α-anomer of N4,N4-dimethyl-5-azacytidine 24. The connection of the base-pairing ability of carbamoylguanidines with the mutagenicity of 2'-deoxy-5-azacytidine (2) as well as the mechanism of inhibition of DNA methyltransferase by this nucleoside analogue is discussed. In contrast to the unsubstituted 5-azacytidine (1) or its N4-methyl derivatives, none of the N4-alkyl derivatives exhibited any antibacterial or antitumor activity at 100 μg/ml or 10 μmol/l concentrations, respectively.
一系列的 N^4-烷基-5-氮杂胞苷 3a-3h 通过将 4-甲氧基类似物 4 与相应的胺处理而制备。对于丙基、丁基、sec-丁基、苄基或糠基胺,分别分离得到氮杂胞苷 3a-3e 与其水解产物 5a-5e 的聚集体。与 1-甲基-5-氮杂胞嘧啶 (6) 和 2-(甲基氨基)胍 (7) 也得到了类似的聚集体。化合物 7 由胍与甲基异氰酸酯反应制备;2或3当量的反应产生了二或三氨基甲酰衍生物 11 和 12。化合物 7 和 11 与 DMF 二甲缩醛的环化分别得到氮杂胞嘧啶 6 和 13。用吉安嘌呤与 5-氮杂胞嘧啶核苷 1、2 和 15 或 5-氮杂-5,6-二氢胞嘧啶核苷 16 和 17,或者 5-氮杂胞苷 (1) 及其 2'-去氧同分异构体 2 的聚集体,通过共结晶制备。(去氧核糖基氨基甲酰)胍嘧啶的异构体 20a 和 20b 通过去氧核苷酸 2 的水解制备。(核糖基氨基甲酰)胍嘧啶的偏硝酸盐 (8a) 与胞苷 (9) 的聚集体通过两组分的共结晶得到。与上述胺不同,甲氧基核苷 4 与叔丁胺反应,得到了 α-异构体的 O-甲基核糖异尿素 22,它通过 DMF 二甲缩醛环化为 α-异构体的 N^4,N^4-二甲基-5-氮杂胞苷 24。讨论了氨基甲酰胍的碱基配对能力与 2'-去氧-5-氮杂胞苷 (2) 的致突变性以及这种核苷类似物对 DNA 甲基转移酶的抑制机制的关系。与未取代的 5-氮杂胞苷 (1) 或其 N^4-甲基衍生物不同,100 μg/ml 或 10 μmol/l 浓度下,N^4-烷基衍生物均未表现出任何抗菌或抗肿瘤活性。