Herein, we have developed visible-light photoredox-catalyzed decarboxylating carboxylic acids for alkylation of heteroarenes under mild conditions. The transformation occurred smoothly without the requirement of stoichiometric oxidants in the presence of 0.3 equiv of base, which benefited from the release of hydrogen (H2) and carbon dioxide (CO2). Various substrates and functional groups were tolerated. Primary mechanistic studies suggest that an oxidative quenching pathway and a reductive quenching pathway are both possible in the catalytic cycle.

Cleavage of C–O bonds in lignin can afford the renewable aryl sources for fine chemicals. However, the high bond energies of these C–O bonds, especially the 4-O-5-type diaryl ether C–O bonds (~314 kJ/mol) make the cleavage very challenging. Here, we report visible-light photoredox-catalyzed C–O bond cleavage of diaryl ethers by an acidolysis with an aryl carboxylic acid and a following one-pot hydrolysis. Two molecules of phenols are obtained from one molecule of diaryl ether at room temperature. The aryl carboxylic acid used for the acidolysis can be recovered. The key to success of the acidolysis is merging visible-light photoredox catalysis using an acridinium photocatalyst and Lewis acid catalysis using Cu(TMHD)2. Preliminary mechanistic studies indicate that the catalytic cycle occurs via a rare selective electrophilic attack of the generated aryl carboxylic radical on the electron-rich aryl ring of the diphenyl ether. This transformation is applied to a gram-scale reaction and the model of 4-O-5 lignin linkages.

An efficients ynthesis of 2-substituted quinolines from readily availablec yclopropanols and imidamidesh as been developed, where the cyclopropanol acts as aC 3 synthon. With the assistance of ab ifunctional imidamide directing group, the reactiono ccurred via sequential C-H/C-C cleavage and C-C/C-N bond formation.

An unprecedented visible-light photoredox-catalyzed iminyl radical formation by N-H cleavage with H release has been developed. Its application in the synthesis of various isoquinolines and related polyaromatics in high atom economy at ambient temperature by applying a photosensitizer, Acr-Mes ClO, and a new cobalt catalyst, Co(dmgH)(4-CONMePy)Cl is reported. Mechanistic investigations indicated that the generated iminyl radical initiates the cascade C-N/C-C bonds formation and the catalytic cycle occurs by a simultaneous oxidative as well as reductive quenching pathway.