Electrochemical Dehydrogenative Cross‐Coupling of Quinoxalin‐2(1H)‐ones with Amines for the Synthesis of 3‐Aminoquinoxalinones

Abstract

An efficient protocol for the synthesis of 3-aminoquinoxalinones via the electrochemical dehydrogenative C-3 amination of quinoxalin-2(1H)-ones was developed. With aliphatic amines and azoles as the nitrogen sources, a series of 3-aminoquinoxalinones was obtained in up to 99% yield. This direct electrolytic method avoids the use of transition metals and external oxidants, and represents an appealing alternative for the synthesis of 3-aminoquinoxalinones.

Electrochemically Facilitated Oxidative Coupling of Quinoxalin‐2(1H)‐Ones with Diarylphosphine Oxides and Pyrroles: A Green Protocol for C−P, C−C(sp2) Bond Formation

“…Meanwhile, substrate 2 a presented no obvious oxidation peak ranging from −1.0 to 3.0 V versus Ag/AgCl. Furthermore, the CV of mixture of 1 a with 2 a demonstrated oxidant peaks at 1.3 V and 2.1 V. These results indicated that this electrochemical oxidative coupling might begin with the oxidation of 1 a at anode, which is different from Zeng's proposed mechanism in their oxidative amination work …”

“…Compounds containing quinoxalinone moiety are frequently employed as building blocks in pharmaceutical industry. Significant achievements have been recently realized for the direct C3−H functionalization of quinoxalin‐2(1 H )‐ones, including amidation, amination, acylation, arylation, fluoroalkoxylation . Also, Cui et al .…”

Direct Introduction of Sulfonamide Groups into Quinoxalin‐2(1H)‐ones by Cu‐Catalyzed C3‐H Functionalization

“…Next, the loading of catalyst was evaluated and the result revealed that 10% of Cu(PF 6 ) • 4CH 3 CN was suitable for the reaction with the yield of 3 a increasing to 78% (Table 1, entries [12][13]. Subsequently, diverse oxidants including Na 2 S 2 O 8 , PhI(OAc) 2 and PIFA ([Bis (trifluoroacetoxy)iodo]benzene) were also tested again and the results showed that (NH 4 ) 2 S 2 O 8 still was the most appropriate oxidant among the aforementioned oxidants (Table 1, entries [14][15][16]. Finally, several bases (Cs 2 CO 3 , KOAc, etc.)…”

Recent Developments in Direct C–H Functionalization of Quinoxalin-2(1H)-ones via Radical Addition Processes

“…In the case of N-substituents, either unsubstituted, N-alkylor N-allyl-substituted derivatives reacted equally well to give the corresponding products in excellent yields. Zeng and co-workers 52 have demonstrated an electrochemical method for the direct C3 amination of quinoxalin-2(1H)-one derivatives. Many secondary amines reacted well under the optimized conditions to afford the desired 3-aminoquinoxalin-2(1H)-one derivatives (Scheme 59).…”