Visible light photoredox catalysis: conversion of a mixture of thiophenols and nitriles into 2-substituted benzothiazoles <i>via</i> consecutive C–S and C–N bond formation reactions

Natarajan, Palani; Manjeet,; Muskan, .; Brar, Navpreet Kaur; Kaur, Jaskamal Jot

doi:10.1039/c8qo00219c

Cited by 38 publications

(17 citation statements)

References 51 publications

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“…In 2018, Natarajan and co-workers disclosed a photocatalytic system for the modular synthesis of 2-substituted benzothiazoles from nitriles and thiophenols ( Scheme 238 ). 630 Contrary to many literature methods for the preparation of these scaffolds, which rely upon intramolecular S N Ar or cyclization of 2-aminothiophenols onto carboxylic acid derivatives, 631 Natarajan’s method obviates the need for pre-installed reactive functionality. Using a combination of thiophenol, nitrile, and EY as a photocatalyst in DMSO under air with green-light irradiation, the authors demonstrated 21 examples of benzothiazole synthesis, with good to excellent yields (68–92%).…”

Section: S -Centered Radical Generation From S–h Bonds Through Photochemical and Electrochemical Pcet Processesmentioning

confidence: 99%

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

et al. 2021

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We present here a review of the photochemical and electrochemical applications of multi-site proton-coupled electron transfer (MS-PCET) in organic synthesis. MS-PCETs are redox mechanisms in which both an electron and a proton are exchanged together, often in a concerted elementary step. As such, MS-PCET can function as a non-classical mechanism for homolytic bond activation, providing opportunities to generate synthetically useful free radical intermediates directly from a wide variety of common organic functional groups. We present an introduction to MS-PCET and a practitioner’s guide to reaction design, with an emphasis on the unique energetic and selectivity features that are characteristic of this reaction class. We then present chapters on oxidative N–H, O–H, S–H, and C–H bond homolysis methods, for the generation of the corresponding neutral radical species. Then, chapters for reductive PCET activations involving carbonyl, imine, other X=Y π-systems, and heteroarenes, where neutral ketyl, α-amino, and heteroarene-derived radicals can be generated. Finally, we present chapters on the applications of MS-PCET in asymmetric catalysis and in materials and device applications. Within each chapter, we subdivide by the functional group undergoing homolysis, and thereafter by the type of transformation being promoted. Methods published prior to the end of December 2020 are presented.

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Section: S -Centered Radical Generation From S–h Bonds Through Photochemical and Electrochemical Pcet Processesmentioning

confidence: 99%

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

et al. 2021

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“…10 More recently, a visible-light photoredox catalysis for the synthesis of 2-substituted benzothiazoles was reported by Natarajan et al using Eosin Y as a photocatalyst. 11 However, a visible-light-mediated reaction does not necessarily need a photocatalyst. The ground-state association between the electron-rich donor (a nucleophile or reducing agent) and an electron-poor acceptor (an electrophile or oxidizing agent) can generate an electron donor−acceptor (EDA) or charge-transfer (CT) complex which can absorb the visible light and undergo photoexcitation to transfer an electron.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Fu et al have developed a general and efficient visible-light photoredox cross-coupling of aryl halides with arenethiols at room temperature using [fac-Ir(ppy) 3 ] as the photocatalyst . More recently, a visible-light photoredox catalysis for the synthesis of 2-substituted benzothiazoles was reported by Natarajan et al using Eosin Y as a photocatalyst …”

Section: Introductionmentioning

confidence: 99%

Visible-Light-Driven Halogen-Bond-Assisted Direct Synthesis of Heteroaryl Thioethers Using Transition-Metal-Free One-Pot C–I Bond Formation/C–S Cross-Coupling Reaction

et al. 2021

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An efficient protocol for the synthesis of thioether directly from heteroarenes has been developed in the presence of visible light in a one-pot manner at room temperature. This method involves two sequential reactions in a single pot where the formation of the iodinated heteroarene is followed by a transition-metal-free C–S coupling reaction. A wide range of heteroarene and thiol partners (including aliphatic thiols) have been used for the synthesis of thioethers. NMR studies and DFT calculations revealed the presence of a halogen bond between the thiolate anion (halogen bond acceptor) and iodoheteroarene (halogen bond donor). This halogen bonded complex on photoexcitation facilitates the electron transfer from the thiolate anion to the iodoheteroarene at room temperature.

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“…2B, in the nucleophilic addition of nitriles, the most reported reaction partners have been focused on the highly reactive nitrogen, [44][45][46][47][48][49][50][51][52] oxygen, [53][54][55][56][57][58][59][60][61] and sulfur nucleophiles till now. [62][63][64] For carbon pronucleophiles, the related studies are only limited to sp, sp 2 , and sp 3 with α-electron withdrawing group (i.e. cyano, carbonyl, ester groups) carbons, though some elegant work has been made by using transition metal catalysts.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of densely substituted pyridine derivatives from nitriles by a non-classical [4+2] cycloaddition/1,5-hydrogen shift strategy

Wu¹,

He²,

Duan³

et al. 2021

Preprint

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A novel strategy has been established to assemble an array of densely substituted pyridine derivatives from nitriles and o-substituted aryl alkynes or 1-methyl-1,3-enynes via a non-classical [4 + 2] cycloaddition along with 1,5-hydrogen shift process. The well-balanced affinities of two different alkali metal salts enable the C(sp3)-H bond activation as well as the excellent chemo- and regioselectivities. This protocol offers a new guide to construct pyridine frameworks from nitriles with sp3-carbon pronucleophiles, and shows potential applications in organic synthesis and medicinal chemistry.

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Visible light photoredox catalysis: conversion of a mixture of thiophenols and nitriles into 2-substituted benzothiazoles via consecutive C–S and C–N bond formation reactions

Abstract: A novel, visible-light-mediated method for the synthesis of 2-substituted benzothiazoles from thiophenols and alkyl/aryl nitriles in the presence of eosin Y under air atmosphere is disclosed.

Cited by 38 publications

References 51 publications

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

Visible-Light-Driven Halogen-Bond-Assisted Direct Synthesis of Heteroaryl Thioethers Using Transition-Metal-Free One-Pot C–I Bond Formation/C–S Cross-Coupling Reaction

Synthesis of densely substituted pyridine derivatives from nitriles by a non-classical [4+2] cycloaddition/1,5-hydrogen shift strategy

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