Purines. XXIV. Methylation of N6-alkoxyadenines and N6-methyladenine.
作者:TOZO FUJII、TOHRU SAITO、TAKASHI MURAMOTO
DOI:10.1248/cpb.31.4270
日期:——
Methylation of N6-methoxyadenine (3) with an excess of Mel in AcNMe2 at 40°C was found to give the 3-methylated product 8 (17% yield), 9-methylated product 4 (2%), N6, 9-dimethylated product 5 (9%), 7, 9-dimethylated product 6 (27%). 3, 7-dimethylated product 7 (10%), and N6, 3-dimethylated product 9 (11%). Similar treatment of N6-benzyloxyadenine (12) with Mel also afforded a mixture of several products, from which the 7, 9-dimethylated product 13 (X=1) was isolated in 30% yield. Similar methylation of N6-methyladenine (17), prepared in 65% yield from 1-methyladenine (16) by a Dimroth-type rearrangement. gave the 3-methylated product 18 (82% yield), 9-methylated product 20 (1.3%), 3, 7-dimethylated product 19 (1.8%), and 1, 9-dimethylated product 21 (0.3%). On methylation under similar reaction conditions, 18 furnished the 9-methylated product 22 (15% yield) as well as the 7-methylated product 19 (29%), and 20 produced 22 (17%) and 21 (11%). The probable pathways to the six methylated products from 3 and those to the four methylated products from 17 are discussed.
发现在 40°C 下,N6-甲氧基腺嘌呤 (3) 在 AcNMe2 中用过量的 Mel 进行甲基化,得到 3-甲基化产物 8(产率 17%)、9-甲基化产物 4(2%)、N6, 9-二甲基化产物5 (9%)、7, 9-二甲基化产物6 (27%)。 3,7-二甲基化产物7(10%),和N6,3-二甲基化产物9(11%)。用Mel对N6-苄氧基腺嘌呤(12)进行类似处理也得到几种产物的混合物,从中分离出7,9-二甲基化产物13(X=1),产率30%。 N6-甲基腺嘌呤 (17) 的类似甲基化,通过 Dimroth 型重排从 1-甲基腺嘌呤 (16) 制备,产率 65%。得到3-甲基化产物18(产率82%)、9-甲基化产物20(1.3%)、3, 7-二甲基化产物19(1.8%)和1, 9-二甲基化产物21(0.3%)。在相似的反应条件下进行甲基化时,18提供了9-甲基化产物22(产率15%)以及7-甲基化产物19(29%),20产生了22(17%)和21(11%)。讨论了 3 中六种甲基化产物和 17 中四种甲基化产物的可能途径。