Methylation of 1-, 3-, 7-, 9-, and N6-methyladenines bearing a methoxyl group at the N6-position: a synthesis of 7,9-dimethyladenine

The effect of the N6-methoxy group on regioselectivity in methylation of all five possible isomers of N-methyladenine has been investigated. The methoxyl group attached to all these isomers orients methylation to a considerable extent to nitrogen(s) in the same pyrimidine or imidazole moiety that the original N-methyl group is attached to. On the basis of the results of the present methylation study, 7,9-dimethyladeninium perchlorate has been synthesized from 7- or 9-methyl-N6-methoxyadenine.