Arylazoindazole Photoswitches: Facile Synthesis and Functionalization via SNAr Substitution

• Published in: Journal of the American Chemical Society Vol. 139; no. 9; pp. 3328 - 3331
• Main Authors: Travieso-Puente, Raquel, Budzak, Simon, Chen, Juan, Stacko, Peter, Jastrzebski, Johann T. B. H, Jacquemin, Denis, Otten, Edwin
• Format: Journal Article
• Language: English
• Published: American Chemical Society 08-03-2017
• Subjects: Chemical Sciences; Communication
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.6b12585

A straightforward synthetic route to arylazoindazoles via nucleophilic aromatic substitution is presented. Upon deprotonation of the NH group, a C6F5-substituted formazan undergoes facile cyclization as a result of intermolecular nucleophilic substitution (SNAr). This new class of azo photoswitches containing an indazole five-membered heterocycle shows photochemical isomerization with high fatigue resistance. In addition, the Z-isomers have long thermal half-lives in the dark of up to several days at room temperature. The fluorinated indazole group offers a handle for further functionalization and tuning of its properties, as it is shown to be susceptible to a subsequent, highly selective nucleophilic displacement reaction.