Pyrimidine-fused heterocycles are privileged scaffolds that attract great interest due to their biological properties.1 Modification and refinement of such scaffolds is a promising strategy for the development of novel drugs. Recently a new class of tetrazole-fused pyridopyrimidines have evaluated as antidepressants and epilepsy drugs.2 From synthesis perspective, heterocycles with azido-azomethine structural entity are interesting due to present dynamic azide tetrazole equilibrium in solution phase.3 The equilibrium can be shifted towards one or other tautomer by altering ambient conditions such as solvent polarity and temperature. Thus, azide tetrazole ring–chain tautomerism is known to influence SNAr reactivity and regioselectivity.4 Herein we describe efficient and straightforward synthesis method of fused tricyclic tetrazolopyridopyrimidines (Scheme 1). We discovered that diazido substrate 1 undergoes azide–tetrazole equilibrium which directs SNAr to take place at the C-5 position displacing residual azide as a leaving group.