Deciphering single electron transfer ability of fluorene under photoredox conditions Abhishek Kundu, Debashis Adhikari IISER MOHALI, India The synthesis of biaryls bears great importance in organic chemistry, as the unit is seen in a large number of core structural motifs that are found in molecules having tremendous medicinal, agrochemical, and harmaceutical importance. Henceforth, there is a strong interest in furnishing C−C bonds in biaryls by easily accessible routes. Thus, direct C−H arylation of arenes has gained tremendous attention as it can bypass double preactivation for both participating substrates. In the domain of single electron transfer catalysis, simple organic additives in conjunction with KO t Bu are very effective for facile electron transfer. Herein we report fluorene as a radical initiator in its deprotonated form, to promote single electron transfer (SET) under photochemical condition, leading to C–C cross-coupling reactions. A thorough mechanistic probation including Stern-Volmer experiment reveals the photoinduced electron transfer. Multiple key species en route to electron transfer have been isolated or separately synthesized to emphasize the radical amplifying effect of fluorene by offering an initiation mechanistic network, rather than a unique single initiation pathway.
References 1. Murphy.J. A.;Discovery and Development of Organic Super-Electron-Donors. J. Org. Chem. , 2014 , 79 , 3731-3746. 2. Kundu. A. ; Dey. D.; Pal. S.;Adhikari. D.*; Pyrazole-Mediated C−H Functionalization of Arene and Heteroarenes for Aryl− (Hetero)aryl Cross-Coupling Reactions. J. Org. Chem. 2021 , 86 , 15665. 3. Dey. D.; Kundu. A. ; Roy. M.; Pal. S.; Adhikari. D.* Aromatization as the driving force for single eletron transfer towards C–C cross-coupling reactions. Catal. Sci. Technol. , 2022 , 12 , 1934.
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