Purines. XXXII. Synthesis and ring fission of 3,9-dialkyladenines.
作者:Tozo FUJII、Taisuke ITAYA、Tohru SAITO、Kazuyo MOHRI、Mitsuru KAWANISHI、Tsuyoshi NAKASAKA
DOI:10.1248/cpb.37.1504
日期:——
A detailed account is given of the general synthetic route to 3, 9-dialkyladenine salts (3d-I·HX) from N'-alkoxy-1-alkly-5-formamidoimidazole-4-carboxamidines (type 8 or 9), obtainable by ring opening of 1-alkoxy-9-alkyladenines (type 6 or 7). Alkylations of 8a and 9b, c with alkyl halides in HCONMe2 in the presence of NaH or anhydrous K2CO3 produced N'-alkoxy-1-alkyl-5-(N-alkylformamido)imidazole-4-carboxamidines (10d-f and 1lg-l) in good yields. Hydrogenolyses of 10d-f and 11g-l using hydrogen and Raney Ni catalyst in the presence of one molar eq of HCl afforded 1-alkyl-5-(N-alkylformamido)imidazole-4-carboxamidines (12d-l·HCl). On treatment with HCl, HClO4, or Et3N in boiling MeOH or EtOH, the amidines 12d-l·HCl cyclized to give 3, 9-dialkyladenines (3d-l), which were isolated as the HCl or HClO4 salts. 9-Alkyl-3-methyladenine salts (3d, g, j·HX) were alternatively synthesized from 8a and from 9b, c through a 3-step route, which consisted of LiAlH4 reduction of the formamido group, cyclizations of the resulting 5-(methylamino)imidazoles (15a and 16b, c) with CH(OEt)3 to give N6-alkoxy-9-alkyl-3-methyladenines (17a and 18b, c), and dealkoxylation of 17a and 18b, c by catalytic hydrogenolysis. 3, 9-Dialkyladenine salts (3d-l·HX) thusprepared were found to be unstable in alkaline aqueous solution. In 0.1 M aqueous NaHCO3, 3d·HCl and 3f·HClO4 were equilibrated with their ring-opened derivatives, 12d and 12f, respectively, and their equilibrium constants and rates of ring opening and cyclization at 25°C were determined.
提供了3, 9-二烷基腺苷盐(3d-I·HX)的一般合成路线的详细说明,这些化合物是通过开环反应获得的N'-烷氧基-1-烷基-5-甲酰氨基咪唑-4-羧氨基(8或9型)。在NaH或无水K2CO3存在下,使用烷基卤化剂对8a和9b、c进行烷基化反应,产生了N'-烷氧基-1-烷基-5-(N-烷基甲酰氨基)咪唑-4-羧氨基(10d-f和11g-l),得率良好。利用氢气和Raney Ni催化剂,在一个摩尔当量的HCl存在下,对10d-f和11g-l进行氢解反应,得到1-烷基-5-(N-烷基甲酰氨基)咪唑-4-羧氨基(12d-l·HCl)。在用HCl、HClO4或Et3N处理沸腾的甲醇或乙醇时,12d-l·HCl环化生成3, 9-二烷基腺苷(3d-l),它们以HCl或HClO4盐的形式分离。9-烷基-3-甲基腺苷盐(3d, g, j·HX)则通过三步法从8a和9b、c合成,该步骤包括:对甲酰氨基进行LiAlH4还原、将所得的5-(甲基氨基)咪唑(15a和16b, c)与CH(OEt)3环化生成N6-烷氧基-9-烷基-3-甲基腺苷(17a和18b, c),以及通过催化氢解法去烷氧基化17a和18b, c。因此,合成的3, 9-二烷基腺苷盐(3d-l·HX)在碱性水溶液中被发现不稳定。在0.1M的水合NaHCO3中,3d·HCl和3f·HClO4与它们的开环衍生物12d和12f达到了平衡,并确定了它们的平衡常数及在25°C下的开环和环化速率。