ChemInform Abstract: Nucleophilic Ring‐Opening of the Azole and Azine Moieties in 6‐Nitro‐1,2,4‐triazolo[1,5‐a]pyrimidin‐7‐ones.

Abstract

Nucleophilic Ring-Opening of the Azole and Azine Moieties in 6-Nitro-1,2,4-triazolo[1,5-a]pyrimidin-7-ones.-The influence of substitution pattern of the triazolopyrimidines and of the nature of nucleophile on the direction of nucleophilic ring opening reaction of title triazolopyrimidinones (I), (X), (XI), and (XIV) is studied. Thus, in the presence of a methyl group at position 5 of triazolopyrimidinone [cf. (I)] sterically encumbered secondary amines (IV) react by triazole ring opening, while primary amines (VI) cause pyrimidine ring opening. In contrast, in the absence of 5-methyl group, pyrimidine ring opening takes place even with secondary amines. In the presence of 2-alkyl groups like in compound (X), guanidine formation with secondary amines [as in (V)] is not possible, thus, only aminopyrimidinones like (III) are obtained. -(ULOMSKY, E. N.; VORONIN, V. V.; RUSINOV, V. L.; CHUPAKHIN, O. N.; Russ. Chem. Bull. 50 (2001) 4, 682-688; Urals State Tech. Univ., Ekaterinburg 620002, Russia; EN)