v-Triazolo[4,5-d]pyrimidines (8-azapurines). Part IX. Some nucleophilic addition reactions

Abstract

Several v-triazolo[4,5-d]pyrimidines (8-azapurines) added nucleophilic reagents (shown in parentheses) to give 7-substituted 6,7-dihydro-derivatives (6-substituted 1,6-dihydro-8-azapurines)[shown in square brackets]: v-triazolo[4,5-d]pyrimidine (potassium hydrogen sulphite, barbituric acid, 2-thiobarbituric acid, benzenethiol, and methanol)[7-sulphonato-(1a), 7-(2,4,6-trioxohexahydropyrimidin-5-yl)(1c), 7-(4,6-dioxo-2-thioxohexa-hydropyrimidin-5-yl), 7-phenylthio-, and 7-methoxy-(4a) derivatives, respectively]; 5-amino-v-triazolo[4,5-d]-pyrimidine (2-amino-8-azapurine)(potassium hydrogen sulphite and methanol)[7-sulphonato-(1b) and 7-methoxy-(4d) derivatives]; v-triazolo[4,5-d]pyrimidine-5(4H)-thione (8-azapurine-2-thione)(potassium hydrogen sulphite)[7-sulphonato-derivative (2a; X = S)]; vtriazolo[4,5-d]pyrimidin-5(4H)-one (8-azapurin-2-one)(potassium hydrogen sulphite, methanol, benzenethiol, acetylacetone, ethyl acetoacetate, diethyl malonate, malonamide, and barbituric acid)[7-sulphonato-(2a; X = O), 7-methoxy-(2b), 7-phenylthio-, 7-diacetylmethyl-, 7-(1-ethoxycarbonyl-2-oxopropyl), 7-bis(ethoxycarbonyl)methyl-, 7-dicarbamoylmethyl-, and 7-(2,4,6-trioxo-hexahydropyrimidin-5-yl)(2d) derivatives]. v-Triazolo[4,5-d]pyrimidin-5(4H)-one was reduced by potassium borohydride to the 6,7-dihydro-derivative (2e)(1,6-dihydro-8-azapurin-2-one).

U.v. and ¹H n.m.r. spectra and some ionisation constants are reported and discussed.