Azoacetylenes for the Synthesis of Arylazotriazole Photoswitches

Abstract

We report a modular approach toward novel arylazotriazole photoswitches and their photophysical characterization. Addition of lithiated TIPS-acetylene to aryldiazonium tetrafluoroborate salts gives a wide range of azoacetylenes, constituting an underexplored class of stable intermediates. In situ desilylation transiently leads to terminal arylazoacetylenes that undergo copper-catalyzed cycloadditions (CuAAC) with a diverse collection of organoazides. These include complex molecules derived from natural products or drugs, such as colchicine, taxol, tamiflu, and arachidonic acid. The arylazotriazoles display near-quantitative photoisomerization and long thermal Z -half-lives. Using the method, we introduce for the first time the design and synthesis of a diacetylene platform. It permits implementation of consecutive and diversity-oriented approaches linking two different conjugants to independently addressable acetylenes within a common photoswitchable azotriazole. This is showcased in the synthesis of several photoswitchable conjugates, with potential applications as photoPROTACs and biotin conjugates.

Photocontrolled Energy Storage in Azobispyrazoles with Exceptionally Large Light Penetration Depths

“…Following growing understanding of their structure–property relationships, many derivatives of azoheteroarene switches have been recently developed, incorporating various heteroarenes such as pyrazole, − triazole, − tetrazole, pyrrole, , imidazole, , and isoxazole. , Studies on the PT-MOST properties of azoheteroarene compounds have been rarely conducted, except for arylazopyrazole derivatives with long alkyl functional groups. − Designing photoswitchable azoheteroarenes to enable condensed-phase switching with appropriate phase transitions is a key challenge to overcome in realizing efficient PT-MOST compounds with high energy densities. In this work, we present the design principles of azobispyrazole switches that allow for a reversible phase transition at room temperature upon light irradiation, a substantial heat storage (>300 J/g), and an exceptionally large effective light penetration depth of UV (>1400 μm) and visible light (>1400 μm).…”

Room-Temperature Copper-Mediated Radiocyanation of Aryldiazonium Salts and Aryl Iodides via Aryl Radical Intermediates

“…our previous reports describing in situ generation of iodonium and organoboron precursors for Cu-mediated radiolabeling). Literature reports , have shown that nitrosonium tetrafluoroborate (NOBF 4 ) is an effective reagent for the in situ formation of aryldiazonium salts from anilines. The treatment of aryl–NH 2 with 1.1 equiv of NOBF 4 affords the aryldiazonium tetrafluoroborate salt along with H 2 O.…”

Degradation of Cyclin-Dependent Kinase 9/Cyclin T1 by Optimized Microtubule-Associated Protein 1 Light Chain 3 Beta-Recruiting Coumarin Analogs

“…2a was prepared according to the reported synthetic method . Aniline (2.2 g, 23.2 mmol) was dissolved in 11.5 mL of a 50% aqueous solution of HBF 4 under an ice bath, and sodium nitrite (1.8 g, 25.5 mmol) in 3.6 mL of water was added to the reaction system.…”

“…2a was prepared according to the reported synthetic method. 40 Aniline (2.2 g, 23.2 mmol) was dissolved in 11.5 mL of a 50% aqueous solution of HBF 4 under an ice bath, and sodium nitrite (1.8 g, 25.5 mmol) in 3.6 mL of water was added to the reaction system. The mixture stayed at 0 °C for 1 h. The filter cake was washed with 50% aqueous solution of HBF 4 after filtering, then ethanol, and lastly with ether to obtain 2a (crude product, 3.1 g, yield 71%).…”