Copper-catalyzed oxidative coupling of quinoxalin-2(1H)-ones with alcohols: access to hydroxyalkylation of quinoxalin-2(1H)-ones

Abstract

An efficient protocol for the synthesis of hydroxyl-containing quinoxalin-2(1H)-ones has been developed via the copper-catalyzed cross-coupling reaction of quinoxalin-2(1H)-ones with alcohols with moderate to good yields.

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

“…[2] Traditionally, Nfunctionalized quinoxaline-2,3-diones are prepared through base-promoted condensation reaction between mono N-substituted 1,2-diaminobenzenes and oxalyl chloride (or ethyl chloroglyoxalate) (Scheme 1a). Given the readily available quinoxalin-2(1H)-ones, significant progress has been achieved on the CÀ H bond functionalization of quinoxalin-2(1H)-ones, including the regioselective alkylation, [3] alkoxylation, [4] arylation, [5] acylation, [6] amination, [7] trifluoromethylation [8] and phosphonation reaction [9] . Given the readily available quinoxalin-2(1H)-ones, significant progress has been achieved on the CÀ H bond functionalization of quinoxalin-2(1H)-ones, including the regioselective alkylation, [3] alkoxylation, [4] arylation, [5] acylation, [6] amination, [7] trifluoromethylation [8] and phosphonation reaction [9] .…”

“…[2a,b] However, from a practical and eco-friendly point of view, those procedures still suffer from some drawbacks, such as the difficulties of preparation and isolation of mono N-substituted substrates, the usage of toxic oxalyl chloride and volatile organic solvent, and harsh reaction conditions. Given the readily available quinoxalin-2(1H)-ones, significant progress has been achieved on the CÀ H bond functionalization of quinoxalin-2(1H)-ones, including the regioselective alkylation, [3] alkoxylation, [4] arylation, [5] acylation, [6] amination, [7] trifluoromethylation [8] and phosphonation reaction [9] . During the past decade, water has received much attention as the expected reaction medium for organic reactions due to safety, cost and environmental concerns.…”

Metal‐Free Hydroxyalkylation‐Initiated Radical Cyclization of 1,6‐Enynes with Alcohols

“…Direct α ‐C(sp 3 )−H functionalization of alcohols by oxidative radical reaction leading to the construction of C−C bonds still belongs to a vital and challenging area in modern synthetic chemistry . In this context, a variety of effective α ‐C(sp 3 )−H functionalization of alcohols strategies, including the reaction with alkynes, alkenes, carboxylic acids, phosphonates, vinyl isocyanides and quinoxalin‐2(1 H )‐ones, have been well documented. Among these, the oxidative functionalization of alkenes is of particular synthetic value because of its simple and efficient nature.…”

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

“…[4] So, the efficient synthetic means for introduction of sulfonamide groups into (hetero) aromatic rings have received widespread attention and significant achievements in this field have been accomplished in the last several years. [5][6] On the other hand, the direct C3À H bond functionalizations of the quinoxalin-2(1H)-ones have emerged as powerful tools to synthesize complex quinoxalin-2(1H)-one derivatives, [7][8][9][10][11][12][13][14] especially the 3-aminoquinoxalin-2(1H)-one derivatives. The pioneering studies focused on oxidative cross-dehydrogenation coupling of quinoxalin-2(1H)-ones with primary or secondary amines as the nitrogen sources, and Gulevskaya, Cui, Jain or Phan group independently reported the manganese, copper, iodine or copper-organic framework catalytic systems for this transformation (Scheme 1a).…”