ortho‐Alkylation of Pyridine N‐Oxides with Alkynes by Photocatalysis: Pyridine N‐Oxide as a Redox Auxiliary

Markham, Jonathan P. J.; Wang, Ban; Stevens, Edwin D.; Burris, Stuart C.; Deng, Yongming

doi:10.1002/chem.201901065

Cited by 36 publications

(18 citation statements)

References 63 publications

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“…During the same period, Deng and co-workers described C-2 alkylation of pyridine N-oxides 12 by reacting with aryl acetylenes 38 under visible light illumination (Scheme 16 (a)). [39] The reaction parameters implied that the employment of a protic solvent significantly suppressed the reaction. Pyridine Noxides containing the alkyl-and halogens substituents at ortho-, meta-, and para-positions worked smoothly, while the electron-withdrawing groups (CO 2 Me, NO 2 ) at the para-position furnished the products in poor yields.…”

Section: Alkylation and Acylationmentioning

confidence: 99%

Visible‐Light‐Mediated C‐2 Functionalization and Deoxygenative Strategies in Heterocyclic N‐Oxides

2022

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Heterocyclic N-oxides are prevalent in numerous natural products with broad applications in pharmaceuticals, agrochemicals, material sciences, and asymmetric synthesis. Owing to their profound biological and physiological activity and unique chemical reactivity, the importance of these compounds has stimulated substantial interest among organic synthetic chemists. More importantly, C-2 functionalization of heterocyclic N-oxides, including pyridine-, isoquinoline-, pyrazine-, quinoxaline-, and quinoline N-oxides, is among the most important strategies for heterocyclic functionalization. Besides, deoxygenation of heterocyclic N-oxides has also emerged as a reaction of significance in organic chemistry. In the past decade, visible light photoredox catalyzed C-2 functionalization and deoxygenation of these heterocyclic N-oxides have drawn substantial attention owing to their mild reaction conditions. This review has been categorized based on visiblelight-mediated nondeoxygenative C-2 functionalization (alkylation, fluoroalkylation, arylation, acylation, and amination), deoxygenative C-2 functionalization (sulfonylation, alkynylation, alkylation, and acylation), and deoxygenation (without CÀ H functionaliza-tion) of heterocyclic N-oxides. For most part of the work, the substrate scope, limitation, and mechanism of the reactions have been discussed.

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Section: Alkylation and Acylationmentioning

confidence: 99%

Visible‐Light‐Mediated C‐2 Functionalization and Deoxygenative Strategies in Heterocyclic N‐Oxides

2022

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“…al studied the photocatalyzed orthoalkylation of pyridine N-oxides with ynamides (62), which was also applied to arylacetylenes. [34] Under blue light irradiation in the presence of an acridinium dye, the reaction between various oxazolidinone-and sulfonamide-based ynamides and pyridine or quinolone N-oxides leads to the formation of α-(2-pyridinyl) benzyl amides 66 (Scheme 26). plex 67, through π-π interaction between the phenyl and triple bond of the ynamides with the pyridine.…”

Section: Photocatalyzed Generation Of Radicalsmentioning

confidence: 99%

Ynamides in Free Radical Reactions

Mahe

Cariou

2020

Adv Synth Catal

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In this review we present the transformations that have been developed with ynamides and free radicals. These reactions involve carbon-, heteroatom-or even metalloid-centered radicals and include inter-and intra-molecular reactions. The scope and mechanism of these transformations are discussed in details, including the most recent examples relying on photoredox catalysis. 2.3. Initiation Through the Addition of an External Radical Species 3. Intermolecular Addition of Radicals on the Alkyne Moiety 3.1. Addition of Thiyl Radicals 3.2. Addition of Silyl and Germyl Radicals 3.3. Addition of Carbon Centered Radicals 3.4. Photocatalyzed Generation of Radicals 4. Conclusion

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“…Sridhar 课题组 [12] 基于三氟甲磺酸铜催化炔酰胺与 2-氨基吡啶的分子间选择性胺化反应, 建立了咪唑并 [1,2-a]吡啶化合物的合成方法(Scheme 2b). Deng 课题组 [13] 基于光催化下吡啶 N-氧化物与炔酰胺的酰胺烷基化反应, 建立了 2-吡啶基酰胺化合物合成方法 (Scheme 2c). 根据已有的研究结果, 推测吡啶的氮原子能独立地与炔烃酰胺中的叁键发生加成反应, 生成一种含有烯胺结构的吡啶鎓盐.…”

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“…13 个底物的拓展, 以 65%～90%收率合成了化合物 3a～3m. 这一方法具有理想的区域选择性, 产物以 Z-式为主(Z∶E 可达到 20∶1).3 实验部分3.1 仪器与试剂红外谱图以 Nicolet-FT-IR360 傅立叶变换红外光谱仪, CH 2 Cl 2 液膜法测定; 核磁谱图以 MERCURY-400 型核磁共振仪测定, TMS 为内标, CD 3 OD 为溶剂; 高分辨质谱以 HP6890/5973 型质谱仪测定, ESI 光源.…”

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Trifluoromethyl Sulfonic Anhydride Mediated Addition of Pyridine with Ynamides

Song¹,

Sun²,

LÜ³

et al. 2022

Chinese Journal of Organic Chemistry

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A convenient approach to pyridine quaternary ammonium salts containing enamine fragment has been developed, which features a trifluoromethyl sulfonic anhydride mediated regioselective addition process of pyridine with ynamides. Using this method, a variety of substituted pyridine quaternary ammonium salts containing enamine fragment 3a～3m were prepared in moderate to excellent yields with high regioselectivities (Z∶E up to 20∶1). Keywords ynamides; pyridine; addition reaction; pyridine quaternary ammonium salt 制备简单、性质稳定的炔酰胺, 其分子中的氮原子以 σ 键形式分别与酰基和炔基相连, 产生独特 p-π 共轭体系, 该体系受吸电子型酰基调控, 直接改变了两个炔键碳的反应活性 [1][2] . 从而使炔酰胺结构中叁键 α 位碳原子具有亲电性, β 位碳原子具有亲核性 [3] . 使用不同酸、碱活化炔酰胺时, 反应活性位点会有所不同, 使炔酰胺在反应中出现较高的区域选择性(Scheme 1). 在炔酰胺参与的反应中, 多种活化模式被广泛研究, 主要包括金属试剂活化 [4] 、布朗斯特酸活化 [5] 、路易斯酸活化 [6] 、亲电试剂(卤素)活化 [7] 、碳正离子活化 [8] . 既可作为亲电试剂又可作为亲核试剂的炔酰胺被广泛用于加成反应、氧化反应、还原反应、环加成反应、关环复分解反应 (RCM)反应、自由基反应和金属催化的环异构化反应中 [9] . 近年来, 本课题组也将炔酰胺用于亚胺鎓的加成环化, 与吲哚、酮的选择性加成, 与伯胺、仲胺的氢胺化反应及叔胺导向的芳环 sp 2 杂化 C-H 活化加成反应中 [10] .图式 1 炔酰胺结构中三键的电性分析 Scheme 1 Electrical analysis of three bonds in ynamides 2-氨基吡啶、吡啶鎓盐及吡啶 N-氧化物也被用来与

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ortho‐Alkylation of Pyridine N‐Oxides with Alkynes by Photocatalysis: Pyridine N‐Oxide as a Redox Auxiliary

Cited by 36 publications

References 63 publications

Visible‐Light‐Mediated C‐2 Functionalization and Deoxygenative Strategies in Heterocyclic N‐Oxides

Visible‐Light‐Mediated C‐2 Functionalization and Deoxygenative Strategies in Heterocyclic N‐Oxides

Ynamides in Free Radical Reactions

Trifluoromethyl Sulfonic Anhydride Mediated Addition of Pyridine with Ynamides

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