Novel Progresses in Synthesis Strategies of Aromatic Azo Derivatives

Abstract

Aromatic azo derivatives possess a particular character that is the light driven reversible isomerization between their cis-and trans-forms, which makes them excellent candidates to modulate the relative movement of different moieties. They are widely used not only in the traditional chemical industry, but also in many newly rising areas of science, such as photochemical molecular switch, super-molecular chemistry of host-guest recognition, self-assembly liquid crystal material, analysis of biomedical imaging and chemical, light driven molecular motor, and so on. The development of chromophores with characteristics, like high chemical stability, thermal stability over a wide temperature range and having two forms easily detectable by a method that does not cause irreversible molecular alterations, is a major challenge for researchers who focus their interest in this area. With the increasing need for investigating unknown aromatic azo derivatives, many novel efficient synthesis strategies are recently innovated and developed in succession. This critical review covers the various synthetic methods of aromatic azo derivatives reported more recently, with special emphasis on application of arylhydrazine, arylamine, nitroarene, azoxyarene, arylazide, and their derivatives.

Application of aluminum triiodide in organic synthesis

“…Azobenzenes (207) are widely used as dyes in industry, and have potent applications in molecular devices. [120][121] Commonly used reagents for preparation of 207 via deoxygenation of azoxybenzenes (206) include indium trichloride, zinc triflate, and copper(II) triflate. 122 AlI 3 was developed as an efficient deoxygenation agent 116 for syntheses of symmetrical azobenzenes in high yields (Scheme 17D).…”

Synthesis of Novel phenylazo-Substituted Salicylaldimine-Based Boron Difluoride Complexes

“…[7][8][9] In addition, the structure of aromatic azo fragments appears in many organic dyes and indicators. 10 Based on our recent study on β-diketone boron bifluoride complexes, 11 we now report the synthesis of a series of novel N,O-bidentate boron difluoride complexes in which the phenylazo-group is introduced for the first time as far as we are aware.When a mixture of 4-aminoazobenzene (1) and salicylic aldehyde (2a) was heated in refluxing anhydrous ethanol in the presence of a small amount of acetic acid, 6 yellow solid 2-[(1E)-{4-(phenyldiazenyl)phenylimino}methyl]phenol (3a) precipitated with 91% isolated yield (Fig. 1).…”