v-Triazolo[4,5-d]pyrimidines (8-azapurines). Part 22. Synthesis of 2-amino- and 2-oxo-derivatives of N-alkyl-1,6-dihydro-8-azapurines from the corresponding 4-amino-5-aminomethyl-1,2,3-triazoles

Abstract

2-Amino-1,6-dihydro-8-azapurines (1c–e), alkylated on a ring-nitrogen atom, were synthesized from corresponding N-alkyl-4-amino-5-aminomethyl-1,2,3-triazoles, e.g.(2a), and cyanogen bromide. 1,6-Dihydro-8-azapurin-2-ones (3), similarly alkylated, were obtained by ring-closure of N-alkyl-4-amino-5-ethoxycarbonyl-aminomethyl-1,2,3-triazoles, e.g.(2e). Dehydrogenation of six dihydro-compounds with potassium permanganate gave 8-azapurines. These had strong covalent hydrating tendencies to form secondary alcohols of the type (5). Two of the 2-amino-compounds (4a and b) exhibited this property in the cations, and all the oxo-compounds (6) in the neutral species. Physical properties (¹H n.m.r., u.v., i.r.) or typical products were measured and discussed.