Metal‐Free C3 Hydroxylation of Quinoxalin‐2(1H)‐ones in Water

Abstract

A practical protocol for the preparation of quinoxaline-2,3(1H,4H)-diones through direct C (sp 2 )À H hydroxylation of quinoxalin-2(1H)-ones in recyclable DL-α-Tocopherol methoxypolyethylene glycol succinate solution (2 wt% in water) (TPGS-750-M/H 2 O) was developed. The target products were exclusively generated and could be collected through extraction and recrystallization.

Visible-Light-Induced Recyclable g-C3N4 Catalyzed C–H Hydroxylation of Quinoxalin-2(1H)-ones

“…The 1 H, 13 C and 19 F NMR spectra were recorded at 400, 100 and 376 MHz by using a Bruker Avance spectrometer. Chemical shifts were calibrated using residual undeuterated DMSO as an internal reference ( 1 H NMR is calibrated at 2.50 ppm and 13 C NMR at 40.0 ppm). Mass spectra were performed on a spectrometer operating on ESI-TOF.…”

C−H Hydroxylation of Quinoxalin‐2(1H)‐ones through ipso‐Substitution Using tert‐Butyl Nitrite

“…In the last two decades, the direct installation of various functionalities at the C‐3 position of quinoxalin‐2(1H)‐ones has become a popular research topic [15a] . The reactions include C‐3 acylation, [18] arylation, [19] benzylation, [20] cyanation, [21] amidation, [22] hydroxylation, [23] phosphonation, [24] alkoxylation, [25] trifluoromethylation, [26] etc.…”

Metal-Free Trifluoroalkylation of Quinoxalin-2(1H)-ones with Unactivated Alkenes and Langlois’ Reagent

“…Among them, 3-substituted quinoxalin-2-ones have attracted wide interests of synthetic chemists owing to their remarkable pharmacological activity . During the past several years, a variety of C3–H functionalization reactions of quinoxalin-2­(1 H )-ones have been reported for the synthesis of 3-substituted quinoxalin-2-ones. − Very recently, the oxidative C3–H trifluoromethylation of quinoxalin-2­(1 H )-ones using CF 3 SO 2 Na or TMSCF 3 as the trifluoromethylated reagent has been developed in the presence of stoichiometric inorganic oxidants or under photoredox catalysis conditions (Scheme a) . In 2018, Xu and co-workers reported an elegant method for the preparation of C­(CF 3 )­Me 2 -substituted quinoxalin-2­(1 H )-ones via (NH 4 ) 2 S 2 O 8 -mediated decarboxylative 1,1-dimethyltrifluoroethylation of quinoxalin-2­(1 H )-ones with 3,3,3-trifluoro-2,2-dimethyl propanoic acid under a nitrogen atmosphere (Scheme b) .…”