1,2,3-Triazole has become one of the most important heterocycles in current chemistry research, due to its important industrial, agrochemical and pharmaceutical applications, especially in biological science, material chemistry, and medicinal chemistry [1]. Additionally, the chemistry of the tetrazole ring is gaining increasing attention due to its importance in a variety of synthetic and industrial processes and excellent properties as a metabolically stable isosteric replacement for the carboxylic acid moiety and as a cis-peptide bond mimetic [2]. Tetrazoles have also been used as precursors to other heterocycles and in high energy compounds [3]. In the present work, initially the reaction of 2,4-dichloro-6-methylpyrimidin-5- amine (1) with different primary amines in refluxing i-PrOH gave the corresponding secamino derivatives which were consequently treated with NaNO2/HCl solution to yield quantitatively the corresponding diazo derivatives of 5-chloro-3-alkyl-7-methyl-3H- [1,2,3]triazolo[4,5-d]pyrimidine (2a-e). Further reaction of compounds (2a-e) with NaN3 in EtOH was resulted in various derivatives of novel heterocyclic system of tetrazolo[1,5- a][1,2,3]triazolo[4,5-d]pyrimidine (3a-e) that are in equilibrium with azide forms.

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