# A Universal Method for the Synthesis of new Heterocyclic Systems: Pyrimido[2,1‐f][1,2,4]triazines

## TL;DR

This paper introduces a new method to synthesize unique heterocyclic compounds called pyrimido[2,1-f][1,2,4]triazines through a four-step process.

## Contribution

The paper presents a novel four-step synthesis method for creating new pyrimido[2,1-f][1,2,4]triazine heterocyclic systems.

## Key findings

- A four-step synthesis method was developed for pyrimido[2,1-f][1,2,4]triazines.
- The combination of two specific cyclization steps creates a new unique heterocyclic system.
- This method allows for the synthesis of many new heterocyclic systems by combining with other cycles.

## Abstract

The synthesis of pyrimido[2,1‐f][1,2,4]triazines was performed in four steps. Compounds obtained by acylation of the starting amino esters of thieno[2,3‐b]pyridines were reacted with various amines. The resulting amino derivatives underwent cyclization in the presence of hydrazine hydrate leading to new aminomethyl derivatives of thieno[3,2‐d]pyrimidines. Further cyclization of the latter resulted to the synthesis of new unique heterocyclic systems: pyrido[3′′,2′′:4′,5′]thieno[3′,2′:4,5]pyrimido[2,1‐f][1,2,4]triazines. The uniqueness of these systems lies in the fact that even the combination of the last two cycles represents a new heterocyclic system.

The synthesis of pyrimido[2,1‐f][1,2,4]triazines opens up new prospects for the synthesis of many new unique heterocyclic systems. The construction of these two cycles on any other cycles and heterocycles leads to completely new heterocyclic systems.