Electrosynthesis of C3 Alkoxylated Quinoxalin‐2(1<i>H</i>)‐ones through Dehydrogenative C–H/O–H Cross‐Coupling

Jiang, Xinpeng; Yang, Lei; Ye, Zenghui; Du, Xiaofan; Fang, Lei; Zhu, Yu; Chen, Keda; Li, Jianjun; Yu, Chuanming

doi:10.1002/ejoc.201901928

Cited by 44 publications

(14 citation statements)

References 59 publications

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“…demonstrated that the electrochemical deoxygenative functionalization with alkyl carbazates allowed the C3 alkylation of quinoxalin‐2(1 H )‐ones [22d] . Recently, electrochemical oxidative C3 thiolation, [22e] alkoxylation, [22f] decarboxylative alkylation, [22g] alkylation [22h] and phosphorylation [22i] of quinoxalin‐2(1 H )‐ones were reported by several groups. In 2018, Gooßen revealed that the direct electrochemical C−H cyanation of electron‐rich (hetero)arenes could be achieved by using NaCN as the nucleophilic cyano source [23] .…”

Section: Methodsmentioning

confidence: 99%

“…Based on the above experimental results and previous reports, a plausible mechanism for this electrochemical C−H cyanation is proposed in Scheme 6. Firstly, quinoxalin‐2(1 H )‐one 1 a would undergo a single‐electron transfer (SET) oxidation at the anode to generate the radical cation intermediate A [22a,f] . Subsequently, the intermediate A would be captured by the nucleophilic cyano source TMSCN to deliver radical B [25] .…”

Section: Methodsmentioning

confidence: 99%

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Electrochemical Oxidative C−H Cyanation of Quinoxalin‐2(1H)‐ones with TMSCN

Zhan

Tong

et al. 2021

Eur J Org Chem

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Both quinoxalin-2(1H)-ones and nitriles are valuable organic compounds, and it is an interesting task to introduce cyano into quinoxalin-2(1H)-ones. Herein a regioselective CÀ H cyanation of quinoxalin-2(1H)-ones was developed with a nucleophilic cyano source TMSCN under electrochemical oxidative conditions. This process allowed the synthesis of C3 cyanated quinoxalin-2(1H)ones in moderate to excellent yields in the absence of transition-metal catalysts and organic hydroperoxides.Quinoxalin-2(1H)-ones are present in a variety of natural products and can be widely found in pharmaceutical molecules with antimicrobial, antifungal, antithrombotic, and antitumor activities, etc. [1] Quinoxalin-2(1H)-one skeleton can also be utilized as a building block in the design of fluorescent dye and fluorogenic probe. [2] A series of active quinoxalinone derivatives bearing a C3-substituted group has been extensively studied, due to their diverse biological activities. [3] Therefore, the synthesis of C3-substituted quinoxalin-2(1H)-ones has gained much attention in recent years. One of the most efficient methods to access C3-substituted quinoxalin-2(1H)-ones is the direct transformation of quinoxalin-2(1H)-ones without prefunctionalization. [4] The past years have witnessed extensive efforts on the direct C3 arylation, [5] heteroarylation, [6] alkylation, [7] trifluoromethylation, [8a] trifluoroalkylation, [8b] difluoromethylation, [8c] acylation, [9] amination, [10] alkoxylation, [11a] fluoroalkoxylation, [11b] phosphonation [12] or sulfenylation [13] of quinoxalin-2(1H)-ones. Nevertheless, the introduction of a CN group to the C3-position of quinoxalin-2(1H)-ones is still highly desirable.Compounds containing cyano functional group, namely nitriles, are a valuable class of organic compounds due to their wide application in pharmaceuticals, agrochemicals, and materials, etc. [14] Moreover, nitriles are easily converted to other important organic compounds such as amides, carboxylic acids, esters, amines, ketones, aldehydes, etc. via the cyano transformation. [15] Therefore, the facile introduction of a cyano group to organic compounds is synthetically attractive for organic chemists. Chelation-assisted transition-metal-catalyzed CÀ H activation has been well developed for the CÀ H cyanation of arenes [16] or heteroarenes [17] in the past decade (Scheme 1a). However, this strategy required the introduction of directing groups to the substrates and the utilization of expensive Rh, Ru or Pd, etc. transition-metal catalysts. [18] Direct CÀ H cyanation of arenes [19] or heteroarenes [20] is an alternative and efficient protocol because it enables the formation of cyanated products without the prefunctionalization of substrates. In these reactions, the choice of cyano sources was significant for obtaining high efficiency. Electrophilic cyanating reagents, such as BrCN, [19a] N-cyano-N-phenyl-p-toluenesulfonamide (NCTS), [19e,20b] could smoothly react with electron-rich arenes. However, these reagents had some di...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Electrochemical Oxidative C−H Cyanation of Quinoxalin‐2(1H)‐ones with TMSCN

Zhan

Tong

et al. 2021

Eur J Org Chem

View full text Add to dashboard Cite

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“…Jiang et al reported the coupling of quinoxalin-2(1H)-ones with alcohols to afford 3alkoxylated quinoxalin-2(1H)-ones in a simple undivided cell using Pt plate as cathode and graphite rod as an anode and lithium perchlorate as an electrolyte using 5 mA current (Scheme 61). [58] The reaction offered a wide functional group tolerance to afford variously substituted coupled products.…”

Section: Reactions Involving Radical Intermediatesmentioning

confidence: 99%

Latest Advancements in Transition‐Metal‐Free Carbon‐Heteroatom Bond Formation Reactions via Cross‐ Dehydrogenative Coupling

Batra¹,

Singh

2021

Asian J Org Chem

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The development of greener and atom economical methods for carbon-heteroatom (CÀ Het) bond formation is of significant importance in synthetic organic chemistry. In this regard, metal-free cross-dehydrogenative coupling (CDC) represents an attractive approach as it is more facile and environment friendly. This review intends to focus on the recent developments in metal-free CDC reactions for CÀ Het bond formation leading to the synthesis

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“…Generally, alcohols participate in the formation of C-O bonds as nucleophiles. In 2020, Li, Yu and co-workers [26] exploited an efficient electrochemical protocol for the synthesis of 3-alkoxylated quinoxalin-2(1H)-ones through dehydrogenative C-H/O-H cross-coupling (Scheme 21). With graphite rod as anode and Pt plate as cathode, different quinoxalin-2(1H)-ones bearing electron-rich and electronpoor substituents reacted smoothly, affording the corresponding products in moderate to good yields under standard conditions.…”

Section: Electrochemical C -H Alkoxylation Of Quinoxalin-2(1h)-onesmentioning

confidence: 99%

Recent Advances in Electrochemical C(3)—H Functionalization of Quinoxalin-2(1H)-ones

Li¹,

Wang²,

Li³

et al. 2021

Chinese Journal of Organic Chemistry

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Quinoxalinone and its derivatives are a class of important nitrogen heterocyclic compounds, which widely exist in natural products, drugs and functional materials. Therefore, the C-H functionalization of quinoxalinone has attracted extensive attention of chemical workers. In recent years, electrochemical synthesis directly uses electron as a "clean reagent" to participate in redox reaction without additional redox reagent, which has the characteristics of mild reaction conditions and good atom economy. This method meets the requirements of green chemistry and sustainable development. With the in-depth study on the mechanism of electrochemical synthesis and the standardization of reaction equipment, this method has become a powerful tool for functionalization of quinoxalineones. The recent advances in the electrochemical C(3)-H functionalization of quinoxaline-2(1H)-one are summarized. The reaction transformation conditions and mechanisms are systematically discussed, and the challenges and future directions of this field are included.

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Electrosynthesis of C3 Alkoxylated Quinoxalin‐2(1H)‐ones through Dehydrogenative C–H/O–H Cross‐Coupling

Cited by 44 publications

References 59 publications

Electrochemical Oxidative C−H Cyanation of Quinoxalin‐2(1H)‐ones with TMSCN

Electrochemical Oxidative C−H Cyanation of Quinoxalin‐2(1H)‐ones with TMSCN

Latest Advancements in Transition‐Metal‐Free Carbon‐Heteroatom Bond Formation Reactions via Cross‐ Dehydrogenative Coupling

Recent Advances in Electrochemical C(3)—H Functionalization of Quinoxalin-2(1H)-ones

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