Visible Light‐Induced Photocatalytic C−H Perfluoroalkylation of Quinoxalinones under Aerobic Oxidation Condition

Abstract

An efficient approach using a photocatalytic strategy for C−H perfluoroalkylation of quinoxalinones under aerobic oxidation condition has been developed. Such transformation employs readily available sodium perfluoroalkanesulfinates as perfluoroalkylation reagents and demonstrates good functional group compatibility, affording corresponding products in moderate to good yields. Compared with previous procedures, this protocol uses oxygen as oxidant, and avoids the use of external additive. A radical mechanism is involved in this perfluoroalkylation reaction.magnified image

Direct C–H difluoromethylation of heterocycles via organic photoredox catalysis

“…It should be noted that these protocols of direct difluoromethylation of heterocycles need either expensive/toxic metal catalysts or external oxidants and strictly inert conditions, which narrow the functional group tolerance and limit the substrate scope. During the submission of this manuscript, Duan and Xia reported an efficient photocatalytic strategy for C-H perfluoroalkylation of quinoxalinones under aerobic oxidation conditions, however, the corresponding difluoromethylation has not been reported 52 approaches to achieve direct C-H difluoromethylation of heterocycles, which can overcome the above-mentioned defects and avoid the safety problems with stoichiometric oxidant at a larger scale.…”

Metal‐, Photocatalyst‐, Light‐ and Electrochemical‐Free C‐3 Trifluoromethylation of Quinoxalin‐2(1H)‐ones, Imidazo[1,2‐a]pyridines and 2H‐Indazoles

“…Further, to demonstrate the synthetic utility of this method, biologically active compound caffeine ( 9 ) [39] and synthetically important starting material 6‐amino‐1,3‐dimethyluracil ( 11 ) [40] were reacted with sodium triflinate under the standard reaction conditions. Both produced the respective trifluoromethylated products 10 & 12 in 87 % (35 % yield reported in the literature [26c] ) and 82 % yield (Scheme 6).…”

Recent Advances in Photocatalytic Functionalization of Quinoxalin‐2‐ones

“…Two months later, the research group of Duan developed a protocol in which quinoxalin-2-ones could be trifluoromethylated and perfluoroalkylated using sodium sulfinates along with Eosin Y as photocatalyst and DMSO as solvent. [50] Applying these conditions, the authors could access a collection of forty differently substituted quinoxalin-2-ones with diverse perfluoroalkylsodium sulfinates in good yields (Scheme 30). The reaction tolerates the presence of several functional groups at the aromatic ring as well as at the amidic nitrogen.…”