作者:M. Alice Carvalho、Teresa M. Esteves、M. Fernanda Proença、Brian L. Booth
DOI:10.1039/b400171k
日期:——
An extremely simple method for the selective synthesis of 9-aryl and 9-alkyl 6-alkoxy or 6-alkoxyformimidoylpurines from the corresponding 6-cyanopurines is described. The reaction is carried out with methanol or ethanol in the presence of DBU. At room temperature, nucleophilic attack by the primary alcohol occurs selectively on the cyano carbon atom, leading to 6-alkoxyformimidoylpurines in good yields. Heating the reaction mixture at a temperature greater than or equal to 78 °C leads to nucleophilic substitution of the substituent in the 6-position by the alkoxy group, generating the corresponding 6-alkoxypurines, also in excellent yields. The 6-alkoxyformimidoylpurines were used as intermediates in the synthesis of 6-carboxamidinopurines by reaction with methylamine (for 9-methylpurine 5a) or methyl ammonium chloride (for 9-arylpurines 5b and 5c).
本文介绍了一种极其简单的方法,可从相应的 6-氰基嘌呤中选择性合成 9-芳基和 9-烷基 6-烷氧基或 6-烷氧基甲酰亚胺基嘌呤。反应是在 DBU 存在下与甲醇或乙醇进行的。在室温下,伯醇的亲核作用选择性地作用于氰基碳原子,从而生成产率较高的 6-烷氧基甲酰亚胺基嘌呤。在高于或等于 78 °C 的温度下加热反应混合物,6-位上的取代基就会被烷氧基亲核取代,生成相应的 6-烷氧基嘌呤,收率也非常高。这些 6-烷氧基甲酰亚胺基嘌呤被用作中间体,通过与甲胺(9-甲基嘌呤 5a)或甲基氯化铵(9-芳基嘌呤 5b 和 5c)反应合成 6-甲脒基嘌呤。