Aerobic Visible‐Light Induced Intermolecular S−N Bond Construction: Synthesis of 1,2,4‐Thiadiazoles from Thioamides under Photosensitizer‐Free Conditions

Abstract

Aerobic visible-light induced intermolecular SÀ N bond construction has been achieved without the addition of photosensitizer, metal, or base. With this strategy, 1,2,4-thiadiazoles can be obtained from thioamides. Preliminary mechanistic investigation suggested that the excited state of thioamides undergoes a single-electron-transfer (SET) process to afford thioamidyl radicals, which can be further transformed into a 1,2,4-thiadiazole through desulfurization and oxidative cyclization. The reaction has good functional group tolerance and represents a green method for the construction of SÀ N bonds.

Visible photons as ideal reagents for the activation of coloured organic compounds

“…The mechanism hypothesized indicated a PET reaction between 47.1 and oxygen to deliver the thioamidyl radical 47.3 that was captured by another molecule of 47.1 , generating the heterocycle via an intermolecular nucleophilic addition and desulfurization. 193…”

Sulfur‐Centered Radicals in Visible Light Isocyanide Photochemistry

“…While visible light photoredox reactions involving thioketones, thioamides, and benzothioates mainly afforded desulfurization products [67,68] and heterocyclic compounds such as thiazoles [69] and thiadiazoles, [70,71] the current section will highlight the handful of transformations harnessing C=S containing compounds to form C-centered radicals, such as xanthates and Nhydroxy-2-thiopyridones.…”