Metal-free C3–H acylation of quinoxalin-2(1H)-ones with α-oxo-carboxylic acids

Abstract

Direct C3-H acylation of quinoxalin-2(1H)-ones with α-oxocarboxylic acids under thermo conditions promoted by PIDA has been achieved in moderate to good yield. Mechanistic study revealed that the reaction proceeds via...

Visible Light-Promoted Radical Relay Cyclization/C–C Bond Formation of N-Allylbromodifluoroacetamides with Quinoxalin-2(1H)-ones

“…6 Hz,1H),2H), 3.73 (t, J = 8.9 Hz, 1H), 3.49 (dd, J = 17. 5,3.6 Hz,1H),1H),2H) 3-((1-Cyclohexyl-4,4-difluoro-5-oxopyrrolidin-3-yl)methyl)quinoxalin-2(1H)-one (3la). Yellow solid: the product was purified by flash column chromatography (PE−PE/EtOAc = 1:9 to 1:4) to afford the desired product; 31.6 mg, 42% yield; mp 221−223 °C; IR (neat) v 1719, 1657, 906, 891, 753, 720, 588 cm −1 ; 1 H NMR (400 MHz, CDCl 3 ) δ 12.59 (s, 1H), 7.84 (d, J = 7.9 Hz, 1H), 7.56 (t, J = 7.…”

“…1,2 Direct functionalization of quinoxalin-2(1H)-ones, especially at the C3 position, is a convenient method to expand their structural diversity. In recent years, impressive advances have been made to access 3-substituted quinoxalin-2(1H)-ones through transition-metal-catalyzed or visible light-induced functionalization, 3 including arylation, 4 acylation, 5 phosphonation, 6 amination, 7 or trifluoromethylation 8 (Scheme 1a). 9 Despite that a range of functionalized quinoxalin-2(1H)-ones have been prepared, the structural complexity and chemical space for this class of hetereocycles are still highly expected to be expanded by exploiting new synthetic pathways.…”

Sunlight Induced and Recyclable g-C3N4 Catalyzed C-H Sulfenylation of Quinoxalin-2(1H)-Ones

“…Quinoxalin-2(1 H )-one is a privileged structural moiety, which exhibits various biological activities and pharmacological properties [ 1 , 2 ]. Consequently, a large number of 3-substituted quinoxalinones are prepared via direct C3–H functionalization of quinoxalin-2(1 H )-ones in recent years, mainly including alkylation [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ], arylation [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ], acylation [ 26 , 27 , 28 , 29 , 30 , 31 ], alkoxylation [ 32 , 33 , 34 , 35 ], sulfenylation [ 36 , 37 , 38 ], amination [ 39 , 40 , 41 , 42 , 43 , 44 ], phosphonation [ 45 , 46 , 47 , 48 , 49 ] and trifluoromethylation [ 50 , …”

Regioselective C-3-alkylation of quinoxalin-2(1H)-ones via C–N bond cleavage of amine derived Katritzky salts enabled by continuous-flow photoredox catalysis

“…More recently, Xuan et al explored a method for alkylation of quinoxalin-2(1H)-ones that utilizes 4-alkyl-1,4-dihydropyridines (R-DHPs) as alkyl radical precursors via visible light photoredox catalysis. 10 Several research groups, including Zhang, 11 Yu, 12 Zhao, 13 Li, 14 Wang 15 and Yang 16 were developed different strategies for functionalizing quinoxalin-2(1H)-ones, which are well documented in the current literature. Despite these elegant achievements, several drawbacks still remain in the previous reports including expensive starting materials, longer reaction times, limited substrate scope and use of transition metal catalysts.…”

“…9 More recently, Xuan et al explored a method for alkylation of quinoxalin-2(1 H )-ones that utilizes 4-alkyl-1,4- dihydropyridines (R-DHPs) as alkyl radical precursors via visible light photoredox catalysis. 10 Several research groups, including Zhang, 11 Yu, 12 Zhao, 13 Li, 14 Wang 15 and Yang 16 were developed different strategies for functionalizing quinoxalin-2(1 H )-ones, which are well documented in the current literature.…”