Transition-metal-free direct C-3 alkylation of quinoxalin-2(1H)-ones with ethers

Abstract

An efficient protocol for the synthesis of 3-alkyl quinoxalin-2(1H)-ones has been developed via the transition-metal-free cross-coupling reaction of quinoxalin-2(1H)-ones with ethers with moderate to good yields under relatively mild conditions.

Diacetyl as a “traceless” visible light photosensitizer in metal-free cross-dehydrogenative coupling reactions

“…Traditional methods relied on thermo-cleavage of O–O bonds; however, demands of high reaction temperatures might deteriorate the reaction selectivity and functional group tolerance. Also, heating explosive peroxides could cause safety concerns and limit the reaction scale 10. To solve these issues, visible light-mediated CDC with an iridium photocatalyst [Ir(dF(CF 3 )ppy) 2 (dtbbpy)]PF 6 at room temperature was introduced by MacMillan 11.…”

Transition‐Metal‐Free Radical C−H Methylation of Quinoxalinones with TBHP

“…Based on the above‐mentioned results and previous reports, a proposed reaction pathway is proposed in Scheme . Initially, thermal decomposition of TBHP generates ter t‐butoxyl radical and hydroxyl radical.…”

“…In particular, more attention was paid to the synthesis of C3‐functionalized quinoxalin‐2(1H)‐one analogues, such as alkylation, arylation, acylation, amination, and phosphonation . Especially, the direct hydroxyalkylation, benzylation, oxyalkylation and cyanoalkylation of quinoxalin‐2(1H)‐ones synthesis of 3‐alkylquinoxalin‐2(1H)‐ones has been reported (Scheme , a–). However, to the best of our knowledge, the synthesis of quinoxalin‐2(1H)‐ones bearing a methly substituent at the C3 position via direct C–H bond functionalization has not been reported.…”

Visible Light‐Induced Regioselective Decarboxylative Alkylation of the C(sp2)−H Bonds of Non‐Aromatic Heterocycles

“…Despite these important advances, current methods suffer from elevated reaction temperatures and the use of strong oxidants. Due to the common use of peroxides as radical initiators and terminal oxidants, the substrate scope is limited to those with a relatively weak C−H bond that can be selectively and homolytically cleaved, such as alkylbenzenes, tertiary amines and (cyclo)alkyl ethers as well as cycloalkanes, restricting the application of this strategy. Therefore, the development of mild and general methods for the alkylation of these heterocyclic derivatives is still desirable.…”