A photoredox-catalyzed approach for formal hydride abstraction to enable C –H functionalization with nucleophilic partners (F, C, O, N, and Br/Cl)

Transition-metal-free regioselective and stereoselective C(sp2)–C(sp3) coupling of enamides with ethers or alkanes via photoredox-catalyzed cross-dehydrogenative coupling reactions

“…Stern-Volmer experiments showed that only TBPB and BPO were eligible to quench the excited Eosin Y* as compared to TBHP and DTBP (see the ESI † for details). In addition, the tert-butyloxy radical was considered to be a better hydrogen abstractor than the benzoxy radical, 17 which explained the lower yield of 2a when BPO was utilized as the oxidant (Table 1, entry 15 vs. entry 5). Decreasing the amount of Eosin Y resulted in a decrease of the yield of 2a (Table 1, entries 16 and 17).…”

Benzoates as photosensitization catalysts and auxiliaries in efficient, practical, light-powered direct C(sp3)–H fluorinations

“…Although numerous methods have been developed for fluorination reactions of C–H bonds, such as the fluorination of carbanions, 1 arylpalladium complexes, 2 and the addition of electrophilic fluorine to alkenes, 3 few methods permit the direct fluorination of unactivated C(sp 3 )–H bonds. 4 Such a transformation is particularly advantageous for the late-stage functionalization (LSF) of complex molecules. Especially, since F atoms as H atom bioisosteres impart vastly different – and usually favorable – properties (physical, ADME, lipophilicity) in a pharmaceutical/agrochemical context.…”

Radical Redox Annulations: A General Light-Driven Method for the Synthesis of Saturated Heterocycles

“…Then, anti -Markovnikov addition of this nascent radical to the partner aryl alkene would forge a new bond and yield a linear intermediate bearing both a benzylic radical and the tethered nucleophile. Finally, an ORPC event would follow, wherein single-electron oxidation of the benzylic radical by the oxidized state of the photocatalyst furnishes a reactive carbocation. − Cyclization would then occur through addition of the tethered nucleophilic group to the electrophilic cation to yield the desired annulation product. Importantly, this reaction design should accommodate the use of both a variety of radical types and numerous nucleophilic functional groups with varying tether lengths.…”