Synthesis and Properties of 2-Guanidinopurines

2-Guanidinopurines were prepared as derivatives of 2,6-diamino-9-[2-(phosphonomethoxy)ethyl]-9 H -purine (PMEDAP) ( 1 ), which shows an important antiviral activity. It completes earlier described synthesis of 6-guanidinopurine derivatives. The title compounds were obtained by the reaction of the corresponding 2-chloropurines with guanidine. 2- And 6-guanidinopurines were used as model compounds for determination of dissociation constants (p K a ) of their ionogenic groups by capillary zone electrophoresis. The p K a values of ionogenic groups of the above compounds were compared with those of the corresponding aminopurines. The p K a of guanidino group at the purine moiety varies from 7.77 to 10.32. There is no protonation of N 1 -position in contrast to aminopurines. None of these compounds showed any antiviral activity.