v-Triazolo[4,5-d]pyrimidines (8-azapurines). Part XI. Preparation of 2-benzyl-v-triazolo[4,5-d]pyrimidine (8-benzyl-8-azapurine)

Abstract

4-Formamido-1,2,3-triazole-5-carboxamide (2)(anion) on treatment with benzyl chloride gave the 2-benzyl derivative, which was converted by hot formamide into 2-benzyl-vtriazolo[4,5-d]pyrimidin-7(6H)-one (8-benzyl-8-azapurin-6-one)(3a). The latter, with phosphorus pentasulphide, produced the corresponding 7-thione (3b), which was desulphurised with nickel to give 2-benzyl-6,7-dihydro-v-triazolo[4,5-d]pyrimidine (8-benzyl-1,6-dihydro-8-azapurine) readily oxidised by potassium ferricyanide to 2-benzyl-v-triazolo[4,5-d]pyrimidine (8-benzyl-8-azapurine)(1a). The last-named was also prepared by oxidising 2-benzyl-7-hydrazino-v-triazolo[4,5-d]-pyrimidine (1c), obtained from hydrazine and the 7-methylthio-compound (1b), which was made by methylating the 7-thione (3b). ¹H N.m.r. spectra were recorded and assigned for all substances.