Annulated 1,2,4-Triazoles. A Convenient Synthesis of Thieno[2,3-f][1,2,4]triazolo[1,5-a]azepines: A Novel Triheterocyclic Ring System

Abstract

A synthetic approach to the previously unknown thieno[2,3-f][1,2,4]triazolo[1,5-a]azepine derivatives was efficiently accomplished by cycloaddition of the bicyclic 1-aza-2-azoniaallene salts 6, derived from 6,7-dihydrobenzo[b]thiophen-4(5H)-one hydrazones 4, to the triple bond of nitriles, followed by ring enlargement. The X-ray crystal diffraction analysis of the picrate 10a provided affirmative proof for the structural assignment made.

Key words

1-aza-2-azoniaallene cations - cycloaddition - nitriles - ring enlargement - thieno[2,3-f][1,2,4]triazolo[1,5-a]azepines

References

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