Purines. XLI. An alternative synthesis and the chemical behavior of 7,9-dialkyladeninium salts.
作者:Tohru SAITO、Isao INOUE、Tozo FUJI
DOI:10.1248/cpb.38.1536
日期:——
A full account is given of the chemical behavior observed for 7, 9-dialkyladeninium salts (16). On treatment with boiling 1N aqueous NaOH for 60min, 16a, b, d, e (X=I), 16c (X=Br), and 16f (X=ClO4) rearranged to isomeric N6, 7-dialkyladenines (21a-f) in 50-91% yields. Treatment of the salts with 0.5N aqueous Na2CO3 at room temperature for 30-90min or with Amberlite CG-400 (OH-) in H2O at room temperature gave the ring-opened derivatives 22a-f (in the trans-formamide form) in 56-83% yields, and rate constants for the ring-opening reactions of 16a, b, d-g (X=ClO4) and 16c (X=Br) leading to 22a-g were determined in H2O at pH 9.84 and ionic strength 0.50 at 25°C. Cyclization of 22a with NaH in AcNMe2 at room temperature or with boiling 1N aqueous NaOH produced 21a in 84% or 72% yield, respectively.In solution, the trans-formamides 22 seemed to transform slowly into the cis-formamides 23, attaining equilibria. The existence of such an equilibrium in D2O or Me2SO-d6 at 25°C or in H2O at pH 9.84 and ionic strength 0.50 at 25°C was kinetically confirmed in the case of 22a, and the mechanism of the rearrangement of 16 to 21 through 22 is discussed on the basis of the above kinetic results and Deslongchamps' theory of stereoelectronic control. On treatment with NaBH4 in MeOH at room temperature, 16a (X=I) furnished the 7, 8-dihydro derivative 28 (84% yield), which slowly decomposed in H2O at 60°C to give 22a in 49% yield.The 7, 9-dialkyladeninium salts (16) were found to be obtainable from N'-alkoxy-1-alkyl-5-formamidoimidazole-4-carboxamidines (9) through an alternative synthetic route : Alkylations of 9 with alkyl halides in HCONMe2 in the absence of base, followed by hydrogenolysis of the N'-alkoxy group and cyclizatio (or vice versa) produced 16 in acceptable yields. In order to interpret the proton nuclear magnetic resonance spectrum of 22a, the 2-deuterated species 26 was also synthesized from 24 via 25 and 27.
本文对 7,9-二烷基腺嘌呤盐 (16) 的化学特性进行了全面阐述。用沸腾的 1N NaOH 水溶液处理 60 分钟后,16a、b、d、e(X=I)、16c(X=Br)和 16f(X=ClO4)重新排列为异构的 N6,7-二烷基腺嘌呤(21a-f),产率为 50-91%。在室温下用 0.5N Na2CO3 水溶液处理这些盐 30-90 分钟,或在室温下用 Amberlite CG-400 (OH-) 在 H2O 中处理这些盐,可得到开环衍生物 22a-f(反式甲酰胺形式),收率为 56-83%。84 和离子强度 0.50、温度为 25°C 的 H2O 中测定。在室温下,用 AcNMe2 中的 NaH 或沸腾的 1N NaOH 水环化 22a 生成 21a,产率分别为 84% 或 72%。在 25°C 的 D2O 或 Me2SO-d6 溶液中,或在 25°C 的 H2O 溶液(pH 值为 9.84,离子强度为 0.50)中,这种平衡的存在在 22a 的例子中得到了动力学证实,并根据上述动力学结果和 Deslongchamps 的立体电子控制理论讨论了 16 通过 22 重排为 21 的机理。在室温下,用 NaBH4 在 MeOH 中进行处理,16a(X=I)生成了 7、8-二氢衍生物 28(产率 84%),该衍生物在 60°C 的 H2O 中缓慢分解,生成 22a,产率 49%。通过另一种合成路线:在 HCONMe2 中,在没有碱的情况下,用烷基卤化物对 9 进行烷基化,然后对 N'-烷氧基进行氢解和环化(或反之),以可接受的产率得到 16。为了解释 22a 的质子核磁共振谱,还通过 25 和 27 从 24 合成了 2-氘代物 26。