Alkyl Carbazates for Electrochemical Deoxygenative Functionalization of Heteroarenes

Gao, Yongyuan; Wu, Zheng‐Guang; Yu, Lei; Wang, Yi; Pan, Yi

doi:10.1002/anie.202001571

Cited by 82 publications

(57 citation statements)

References 104 publications

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“…In 2020, Wang, Pan et al. 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.…”

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

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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%

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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“…b) Proposed mechanism for alkyl radical generation and anodic coupling. c) Control experiments to determine the mechanism [96] …”

Section: C‐centered Radicalsmentioning

confidence: 99%

Electrochemical Generation and Use in Organic Synthesis of C‐, O‐, and N‐Centered Radicals

Chicas-Baños

Frontana‐Uribe

2021

The Chemical Record

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During the last decade several research groups have been developing electrochemical procedures to access highly functionalized organic molecules. Among the most exciting advances, the possibility of using free radical chemistry has attracted the attention of the most important synthetic groups. Nowadays, electrochemical strategies based on these species with a synthetic purpose are published continuously in scientific journals, increasing the alternatives for the synthetic organic chemistry laboratories. Free radicals can be obtained in organic electrochemical reactions; thus, this review reassembles the last decade's (2010–2020) efforts of the electrosynthetic community to generate and take advantage of the C‐, O‐, and N‐centered radicals’ reactivity. The electrochemical reactions that occur, as well as the proposed mechanism, are discussed, trying to give clear information about the used conditions and reactivity of these reactive intermediate species.

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“…Notably, tert-butyl carbazate was also compatible with this reaction, furnishing the alkylated product 3r in 26% yield through a decarboxylation process. 11 To demonstrate a potential synthetic application of this reaction, we hydrolyzed 3a at room temperature in 1:1 EtOH-H 2 O (4 mL). The reaction proceeded efficiently to give the expected free acid 3s in 93% yield (Scheme 3).…”

Section: Letter Synlettmentioning

confidence: 99%