o-Phosphinodiarylamides as Reductive Photocatalysts for Dehalogenative and Deaminative Cross-Couplings

The strong electron-donating ability in the photoactivated state and the structural flexibility of organic anions have led to a growing interest in utilizing photoexcited organic anions as reductive photocatalysts to activate inert chemical bonds. Phenolate and thiolate have been extensively studied and utilized as catalysts in a wide range of photocatalytic transformations. In contrast, catalysts employing nitrogen anions for radical generation have received less attention despite the vast chemical possibilities for designing and adjusting catalyst properties. In this work, we reported that diaryl amides possessing ortho-diphenylphosphaneyl substituents function as visible-light photoredox catalysts for the activation of inert aryl halides (chloride and bromide) and aryl ammonium salts to generate aryl radicals for phosphorylation, borylation, arylation, and alkylation with corresponding radical interceptors. The o-phosphinodiarylamide catalysts also activate trifluoromethyl groups in trifluoromethylarene, trifluoroacetate, and trifluoroacetamide for defluoroalkylation with alkenes. Notably, the methods using o-phosphinodiarylamides as catalysts are very efficient for radical generation from large π-extended aryl halides, spiro-conjugated aryl halides, and poly halides, indicating the advantages of the organic anion-based photocatalytic approach for application in synthesizing conjugated molecules as electronic materials and interface modification materials without recourse to transition-metal catalysis.