Heterocyclic Scaffolds Bearing –N=N- Moiety: Recent Advances in the Synthesis of Heterocyclic Azo-Dispersive Dyes

Azo dyes, comprising azo functionalities joined to aromatic sp2-hybridized C-atom or methane, are deployed in industry and can also be exploited as medicine due to their inherent biological activities. This importance renders the synthesis of these category of azo compounds significant and attractive. Herein, the recent synthesis of various derivatives of heterocyclic compounds with azo moiety such as oxazoles, benzoxazine, diindolylmethanes, coumarins, dihydropyridines, imidazoles, schiff bases, pyrazolopyridines, thiazolidines, thiophenes, pyrimido[4,5-e][1, 3, 4]thiadiazines, quinazolines, thiazoles, oxathiine and pyrazoles, are reviewed for the period 2011-2024. Some of azo dispersive dyes have been evaluated based on biological activity or solvatochromism effect which are also deliberated in this review.