Transition-Metal-Free Direct C–H Arylation of Quinoxalin-2(1H)-ones with Diaryliodonium Salts at Room Temperature

Abstract

A method of synthesizing 3-arylquinoxalin-2(1H)-ones using diaryliodonium tetrafluoroborates under mild conditions is described. This protocol has a wide substrate scope and enables direct C-H functionalization. The synthetic potential of this coupling was explored using a range of readily accessible diaryliodonium salts and quinoxalin-2(1H)-ones.

The C3-H Bond Functionalization of Quinoxalin-2(1H)-Ones With Hypervalent Iodine(III) Reagents

“…In the same year, Zhang group reported a method for C3-H arylation of quinoxalin-2(1 H )-ones to give 3-arylquinoxalin-2(1 H )-ones with diaryliodonium salts ( Figure 1B , Equation b) (Yin and Zhang, 2017 ). Diaryliodonium salts are generally used in organic synthesis as aryl radical sources due to their easy availability (Yamaoka et al, 2013 ; Wang D. et al, 2014 ).…”

“…Because of their synthetic usefulness and potential biological importance, the introduction of functional groups into the C3-position of the quinoxalin-2(1 H )-ones has already become a research hotspot, and various protocols for the direct C3-H functionalization of quinoxalin-2(1 H )-ones have been reported (Ebersol et al, 2019 ; Gu et al, 2019 ; Hong et al, 2019 ; Li et al, 2019 ; Peng et al, 2019 ; Rostoll-Berenguer et al, 2019 ; Teng et al, 2019 ; Wang et al, 2019a , 2020 ; Xie et al, 2019b ; Zhao et al, 2019 ; Zheng and Studer, 2019 ; Tian et al, 2020 ; Yuan et al, 2020 ). In particular, the C3-H functionalization of quinoxalin-2(1 H )-ones involving hypervalent iodine reagents has drawn wide attention for the aforementioned advantages of hypervalent iodine reagents, mainly including arylation (Paul et al, 2017 ; Yin and Zhang, 2017 ), trifluoromethylation (Wang et al, 2018 ; Xue et al, 2019a ), alkylation (Wang et al, 2019b ; Xie et al, 2019a ; Xue et al, 2019b ; Shen et al, 2020 ), and alkoxylation (Xu et al, 2019 ; Yang et al, 2019 ) of quinoxalin-2(1 H )-ones, which provide convenient and environmentally friendly means for the synthesis of 3-substituted quinoxalinone derivatives. In this mini review, we will focus on the progress being made in the direct C3-H functionalization of quinoxalin-2(1 H )-ones involving the hypervalent iodine reagents and discuss their mechanisms, in order to inspire more applications of hypervalent iodine reagents in related reactions.…”

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

“…In contrast to traditional cross-coupling strategies, radical arylation has emerged as a useful synthetic method for the construction of C-C bonds in organic chemistry. 30 In this context, Zhang and Yin 31 demonstrated the first transitionmetal-free direct C3 arylation of quinoxalin-2(1H)-one derivatives.…”

“…To probe the mechanism of this reaction, Zhang and Yin 31 performed the reaction with the radical trapping reagent TEMPO, which completely inhibited the formation of the desired product. Based on these results, the following mechanism was proposed (Scheme 31).…”

Additive-Free Pd-Catalysed C-2 Arylation of Tryptophan Derivatives with Diaryliodonium Salts

“…1,2 In this regard, diaryliodonium salts are considered to be nontoxic, bench stable and readily available electrophilic arylating agents. They have been applied in a range of reactions, 3,4 such as nucleophilic substitution reactions with nitrogen nucleophiles, [5][6][7] oxygen nucleophiles, [8][9][10][11] carbon nucleophiles [12][13][14][15][16][17][18][19][20] and other systems. [21][22][23][24] As versatile arylation reagents, diaryliodonium salts have received considerable attention in the development of effective and regioselective methods of C-H bond formation.…”