A New Family of Fused Azolo[1,5- a]pteridines and Azolo[5,1- b]purines

Denis A Gazizov; Evgeny B Gorbunov; Gennady L Rusinov; Evgeny N Ulomsky; Valery N Charushin

doi:10.1021/acsomega.0c01849

A New Family of Fused Azolo[1,5- a]pteridines and Azolo[5,1- b]purines

ACS Omega. 2020 Jul 14;5(29):18226-18233. doi: 10.1021/acsomega.0c01849. eCollection 2020 Jul 28.

Authors

Denis A Gazizov¹, Evgeny B Gorbunov¹, Gennady L Rusinov^{1

2}, Evgeny N Ulomsky^{1

2}, Valery N Charushin^{1

2}

Affiliations

¹ Postovsky Institute of Organic Synthesis of Ural Branch of Russian Academy of Sciences, Sofia Kovalevskoy St. 22/20, Ekaterinburg 620108, Russia.
² Department of Organic and Biomolecular Chemistry, Ural Federal University, Mira St. 19, Ekaterinburg 620002, Russia.

Abstract

The nitration of azolo[1,5-a]pyrimidin-7-amines with several nitration agents (such as acetic nitric anhydride, nitronium tetrafluoroborate, and a mixture of concentrated nitric acid and sulfuric acid) has been investigated. It has been shown that, depending on the conditions, the nitration of pyrazolopyrimidin-7-amines bearing electron-withdrawing groups in the pyrazole ring leads to nitration products in the pyrimidine and/or pyrazole ring. The nitration of triazolo[1,5-a]pyrimidin-7-amines with "nitrating mixture" has been optimized, thus allowing us to obtain a series of 6-nitro[1,2,4]triazolo[1,5-a]pyrimidin-7-amines, followed by their reduction into the corresponding [1,2,4]triazolo[1,5-a]pyrimidin-6,7-diamines (yields 86-89%). The latter have been subjected to heterocyclization by a variety of electrophilic compounds (such as CS₂, glyoxal, triethyl orthoformate) with the formation of five- or six-membered annulated cycles.