Purines. LVII. Regioselective Alkylation of N6,9-Disubstituted 8-Oxoadenines: Syntheses of the Sea Anemone Purine Caissarone and Some Positional Isomers and Analogues.
作者:Tohru SAITO、Shigeji MORI、Jun CHIKAZAWA、Tae KANAI、Tozo FUJII
DOI:10.1248/cpb.41.1746
日期:——
The first total synthesis of caissarone hydrochloride (1), a constituent of the sea anemone Bunodosoma caissarum, has been accomplished via a two-step route starting from N6, 9-dimethyl-8-oxoadenine (3), which is obtainable from 9-methyladenine (5) through a four-step route. The key step in the synthesis is the regioselective methylation of 3 at N(3), which has been designed on the basis of a methylation study of N6-benzyl-9-methyl-8-oxoadenine (11). Some positional isomers (19, 24, and 31) and analogues (8, 26, and 32) of 1 have also been synthesized. A 1H-NMR spectroscopic study has suggested that the free base (23) of caissarone is capable of forming a hetero-base pair (such as 41) with 2', 3', 5'-tri-O-acetylguanosine (40) in Me2SO-d6.
我们首次以 N6,9-二甲基-8-氧代腺嘌呤(3)为起点,通过两步法合成了海葵 Bunodosoma caissarum 的成分 caissarone hydrochloride (1),该成分可通过四步法从 9-甲基腺嘌呤(5)中获得。合成的关键步骤是在 N(3)处对 3 进行区域选择性甲基化,这一步骤是在对 N6-苄基-9-甲基-8-氧代腺嘌呤(11)进行甲基化研究的基础上设计的。此外,还合成了 1 的一些位置异构体(19、24 和 31)和类似物(8、26 和 32)。一项 1H-NMR 光谱研究表明,凯沙酮的游离碱(23)能够在 Me2SO-d6 中与 2',3',5'-三-O-乙酰鸟苷(40)形成杂基对(如 41)。