Purines. LXXVII. An Alternative Synthesis of N6-Demethylcaissarone from 9-Methyl-8-oxoadenine by Regioselective N(3)-Methylation: Utilization of the N(7)-Benzyl and N(1)-Benzyloxy Groups as Control Synthons.
作者:Taisuke ITAYA、Tae KANAI、Mayumi SHIMADA、Toshiko NISHIKAWA、Yasutaka TAKADA、Yoshitaka HOZUMI、Shigeji MORI、Tohru SAITO、Tozo FUJII
DOI:10.1248/cpb.45.1601
日期:——
An alternative synthesis of 3, 9-dimethyl-8-oxoadenine (N6-demethylcaissarone) hydrochloride (5a·HCl) starting from 9-methyl-8-oxoadenine (17) is described. The synthesis proceeded through N(7)-benzylation, N(1)-oxidation, and O-benzylation to afford the 1-benzyloxy derivative 25, which afforded the ring-opened formamide derivative 26 on treatment with dilute aqueous NaOH. Methylation of the monocycle 26 with MeI in the presence of K2CO3, followed by acid-catalyzed cyclization and subsequent catalytic hydrogenolysis afforded 5a·HCl. The key intermediate 25 was alternatively prepared from 17 by N-oxidation and subsequent O, N(7)-dibenzylation with PhCH2Br in the presence of K2CO3.
本文描述了一种以 9-甲基-8-氧代腺嘌呤(17)为起点的 3,9-二甲基-8-氧代腺嘌呤(N6-去甲基凯沙酮)盐酸盐(5a-HCl)的替代合成方法。合成过程通过 N(7)-苄基化、N(1)-氧化和 O-苄基化得到 1-苄氧基衍生物 25,用稀 NaOH 水处理后得到开环甲酰胺衍生物 26。在 K2CO3 存在下,用 MeI 将单环 26 甲基化,然后进行酸催化环化和随后的催化氢解,得到 5a-HCl。关键的中间体 25 也是由 17 通过 N-氧化,然后在 K2CO3 存在下用 PhCH2Br 进行 O、N(7)-二苄基反应制备得到的。