Purines. LXV. Preparatory Study for the Syntheses of the Marine Sponge Purines Agelasimines-A and -B: Synthesis and Acetylation of Their N(7)-Benzyl Analogues.
作者:Tozo FUJII、Tohru SAITO、Jun CHIKAZAWA、Yuko NAKAMURA、Masashi OHBA
DOI:10.1248/cpb.42.2461
日期:——
Four-step synthetic routes from 3-methyladenine (10) to 7-benzyl-N6, 3-dimethyladenine (1b) and 7-benzyl-1, 2-dihydro-1, 3-dimethyladenine (2b), selected as models for the marine sponge alkaloids agelasimine-A (1a) and agelasimine-B (2a), respectively, have been established. The key steps involved are regioselective methylations of 7-benzyl-3-methyladenine (8) and 7-benzyl-1, 2-dihydro-3-methyladenine (11). The reaction of 1b with acetic anhydride in pyridine was found to give the monocyclic imidazole derivative 29b. A similar acetylation of 2b yielded the N6-acetyl derivative 20b. When treated with boiling H2O, 20b afforded 7-benzyl-2, 3-dimethylhypoxanthine (21b) and a compound inferred to be the dihydrohypoxanthine derivative 30. Probable pathways to 29b from 1b and to 21b and 30 from 20b are proposed.
从 3-甲基腺嘌呤 (10) 到 7-苄基-N6, 3-二甲基腺嘌呤 (1b) 和 7-苄基-1, 2-二氢-1, 3-二甲基腺嘌呤 (2b) 的四步合成路线,被选为模型分别建立了海洋海绵生物碱阿吉拉西明-A (1a) 和阿吉拉西明-B (2a)。涉及的关键步骤是 7-苄基-3-甲基腺嘌呤 (8) 和 7-苄基-1, 2-二氢-3-甲基腺嘌呤 (11) 的区域选择性甲基化。发现1b与乙酸酐在吡啶中反应得到单环咪唑衍生物29b。 2b 的类似乙酰化产生 N6-乙酰基衍生物 20b。当用沸腾的水处理时,20b得到7-苄基-2,3-二甲基次黄嘌呤(21b)和推断为二氢次黄嘌呤衍生物30的化合物。提出了从1b到29b以及从20b到21b和30的可能途径。