1,2,4-Triazolo[1,5-a]pyrimidines

TLDR: The formation of 1,2,4-triazolo [1,5-a] pyrimidines (TPs) was first reported by Biilow and Haas.

Abstract: Publisher Summary The formation of 1,2,4-triazolo [1,5-a] pyrimidines (TPs) was first reported by Biilow and Haas Over the next 50 years, only a few papers and patents on TPs were published, which were included in Mosby's comprehensive monograph on “Heterocyclic Systems with Bridgehead Nitrogen Atoms” Most syntheses of TPs start either from a 1,2,4-triazole derivative or from a pyrimidine residue and need annulation of a second heterocyclic ring Preferably 5-amino-1,2,4-triazoles (AT) and 2-hydrazinopyrimidines (HP) are used as starting synthons In the synthesis of TPs from HPs, intermediates are believed to exist and have been isolated in many cases These products and other acylated HPs may serve as convenient starting materials for cyclization reactions Acylated HPs are also prepared from 2-alkylthiopyrimidines and acylhydrazines and, further, cyclized in situ to triazolopyrimidines Many TPs have been tested as potential growth inhibitors of microorganisms, because they are isomeric to purines and in some cases can be converted to nucleoside analogs