Investigation of the photochemical behavior of allomaltol-containing 2-aminothiazole derivatives

In the present communication, a comprehensive study of the photochemical behavior of terarylenes with a 2-aminothiazole bridge unit and an allomaltol substituent was performed. It was shown that for the considered substrates, two types of photoprocesses can be realized. By controlling the structure of the starting material, the photoprocess can be directed toward the 6 pi-electrocyclization of the 1,3,5-hexatriene system or the ESIPT-induced contraction of the pyranone ring. Relying on data from DFT calculations and UV-vis spectroscopy, the key features of the observed phototransformations were discussed. The investigated thiazole-containing terarylenes were utilized as a scaffold for the construction of photoacid generators (PAGs). Based on the performed research, a synthetic methodology was developed leading to series of 23 novel polycyclic photoproducts and a set of thiazole-containing salts with a quinoxaline part.