Metal & Surfactant-Free oxidation of Quinoxalin-2(1H)-ones: Access to Quinoxaline-2,3-diones

Visible-Light Promoted Regioselective Oxygenation of Quinoxalin-2(1H)-ones Using O2 as an Oxidant

“…48 In addition Ji and co-workers demonstrated that (NH 4 ) 2 S 2 O 8 workerd well for same transformation. 49 We have reported recently the C-3 hydroxylation of quinoxalin-2(1H)-ones to access quinoxaline-2,3-diones using tert-butyl nitrite (TBN) via ipso. 50 However, the use of stoichiometric amount of oxidants and heating conditions were requirement in these protocols.…”

“…The classical synthesis of N -functionalized quinoxaline-2,3-diones utilize base-mediated reactions of mono N -substituted 1,2-diamino benzenes and oxalyl chloride (or ethyl chloroglyoxylate). , The disadvantages of these methods are the use of strong bases and toxic oxalyl chloride, and difficulties in synthesizing and isolating mono N -substituted substrates. , To overcome these drawbacks, He and co-workers reported the synthesis of quinoxaline-2,3-diones via C-3 hydroxylation of quinoxalin-2­(1 H )-ones using (NH 4 ) 2 S 2 O 8 . In addition Ji and co-workers demonstrated that (NH 4 ) 2 S 2 O 8 workerd well for same transformation . We have reported recently the C-3 hydroxylation of quinoxalin-2­(1 H )-ones to access quinoxaline-2,3-diones using tert -butyl nitrite (TBN) via ipso .…”

Ionic liquid-catalysed regioselective oxygenation of quinoxalin-2(1H)-ones under visible-light conditions

“…12 A few reports on the direct C–H oxygenation of quinoxalin-2(1 H )-ones are available to date, which include; (i) graphitic carbon nitride (g-C 3 N 4 ) 13 and 9-mesityl-10-methylacridinium perchlorate as photocatalysts with blue LEDs, 14 (ii) through ipso -substitution using tert -butyl nitrite, 15 and (iii) oxidative hydroxylation with ammonium persulphate as an oxidant. 16 In addition, direct synthesis of hydroxylated quinoxalin-2(1 H )-ones from o -phenylene diamines and oxalyl chloride or ethyl chloroacetate was also reported. 10 b ,17 Although some of these transformations are elegant (Scheme 1), they demand the requirement of either expensive metal catalysts or stoichiometric oxidants such as (NH 4 ) 2 S 2 O 8 and photocatalysts.…”