scholarly journals Recent application of visible-light induced radicals in C–S bond formation

RSC Advances ◽  
2020 ◽  
Vol 10 (34) ◽  
pp. 20046-20056 ◽  
Author(s):  
Vishal Srivastava ◽  
Pravin K. Singh ◽  
Arjita Srivastava ◽  
Praveen P. Singh
Keyword(s):  
Electron Transfer ◽  
Visible Light ◽  
Organic Compounds ◽  
High Efficiency ◽  
Bond Formation ◽  
Single Electron ◽  
Single Electron Transfer ◽  
Recent Application

The sulphur centered radicals, produced from various organic compounds, in high efficiency by single-electron-transfer (SET) oxidation.

scholarly journals Intermolecular oxyarylation of olefins with aryl halides and TEMPOH catalyzed by the phenolate anion under visible light

2020 ◽  
Vol 11 (27) ◽  
pp. 6996-7002
Author(s):  
Kangjiang Liang ◽  
Qian Liu ◽  
Lei Shen ◽  
Xipan Li ◽  
Delian Wei ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Visible Light ◽  
Aryl Halides ◽  
Single Electron ◽  
Single Electron Transfer ◽  
Strong Reduction ◽  
Aryl Radicals ◽  
Reduction Potentials

The phenolate anion was developed as a new photocatalyst with strong reduction potentials (−3.16 V vs. SCE) to reduction of aryl halides to aryl radicals through single electron transfer.

scholarly journals Alcohol-Initiated Dediazoniation of Aryldiazonium Ions to Aryl Radicals: A Simple and Efficient Route to Arylboronates

2018 ◽  
Vol 42 (9) ◽  
pp. 481-485
Author(s):  
Xiulian Zhang ◽  
Zhicheng Zhang ◽  
Yongbin Xie ◽  
Yujie Jiang ◽  
Ruibo Xu ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Bond Formation ◽  
Single Electron ◽  
Single Electron Transfer ◽  
Aryl Radical ◽  
Radical Species ◽  
Aryl Radicals ◽  
Efficient Access ◽  
Efficient Route ◽  
Operational Simplicity

A simple and efficient access to arylboronates was achieved with methanol-initiated borylation of aryldiazonium salts. Reduction of aryldiazonium ions by single electron transfer from methanol affords aryl radical species, which undergo a subsequent C–B bond formation with bis(pinacolato)diboron. This highly practical borylation process, which can be carried out on the gram-scale, enjoys operational simplicity as well as mild and catalyst-free conditions.

Electronically Asynchronous Transition States for C-N Bond Formation by Electrophilic [Coᴵᴵᴵ(TAML)]-Nitrene Radical Complexes Involving Substrate-to-Ligand Single-Electron Transfer and a Cobalt-Centered Spin Shuttle

2019 ◽  
Author(s):  
Nicolaas P. van Leest ◽  
Martijn A. Tepaske ◽  
Jarl Ivar van der Vlugt ◽  
Bas de Bruin
Keyword(s):  
Electron Transfer ◽  
Bond Formation ◽  
Macrocyclic Ligand ◽  
Transition States ◽  
Lone Pair ◽  
Single Electron ◽  
Nucleophilic Attack ◽  
Single Electron Transfer ◽  
Radical Species ◽  
Nitrene Transfer

The oxidation state of the redox non-innocent TAML (Tetra-Amido Macrocyclic Ligand) scaffold was recently shown to affect the formation of nitrene radical species on cobalt(III) upon reaction with PhI=NNs [J. Am. Chem. Soc. 2020, DOI: 10.1021/jacs.9b11715]. For the neutral [Co<sup>III</sup>(TAMLsq)] complex this leads to the doublet (S = ½) mono-nitrene radical species [Co<sup>III</sup>(TAMLq)(N<sup>•</sup>Ns)], while a triplet (S = 1) bis-nitrene radical species [Co<sup>III</sup>(TAML<sup>q</sup>)(N<sup>•</sup>Ns)<sub>2</sub>]<sup>‒</sup> is generated from the anionic [Co<sup>III</sup>(TAML<sup>red</sup>)]<sup>‒</sup> complex. The one-electron reduced Fischer-type nitrene radicals (N<sup>•</sup>Ns<sup>‒</sup>) are formed through single (mono-nitrene) or double (bis-nitrene) ligand-to-substrate single-electron transfer (SET). In this work we describe the reactivity and mechanisms of these nitrene radical complexes in catalytic aziridination. We report that [Co<sup>III</sup>(TAML<sup>sq</sup>)] and [Co<sup>III</sup>(TAML<sup>red</sup>)]<sup>‒</sup> are both effective catalysts for chemoselective (C=C versus C‒H bonds) and diastereoselective aziridination of styrene derivatives, cyclohexene and 1-hexene under mild and even aerobic (for [Co<sup>III</sup>(TAML<sup>red</sup>)]<sup>‒</sup>) conditions. Experimental (Hammett plots, radical inhibition, catalyst decomposition tests) and computational (DFT, CASSCF) studies reveal that [Co<sup>III</sup>(TAML<sup>q</sup>)(N<sup>•</sup>Ns)], [Co<sup>III</sup>(TAML<sup>q</sup>)(N<sup>•</sup>Ns)<sub>2</sub>]<sup>‒</sup> and [Co<sup>III</sup>(TAML<sup>sq</sup>)(N<sup>•</sup>Ns)]<sup>–</sup> are key electrophilic intermediates in the aziridination reactions. Surprisingly, the electrophilic one-electron reduced Fischer-type nitrene radicals do not react as would be expected for nitrene radicals (i.e. via radical addition and radical rebound). Instead, nitrene transfer proceeds through unusual electronically asynchronous transition states, in which (partial) styrene substrate to TAML ligand (single) electron transfer precedes C-N coupling. The actual C-N bond formation processes are best described as involving a nucleophilic attack of the nitrene (radical) lone pair at the thus (partially) formed styrene radical cation. These processes are coupled to TAML-to-cobalt and cobalt-to-nitrene single-electron transfer, effectively leading to formation of an amido-[gamma]-benzyl radical (Ns–N–CH<sub>2</sub>–<sup>•</sup>CH–Ph) bound to an intermediate spin (S = 1) cobalt(III) center. Hence, the TAML moiety can be regarded to act as a transient electron acceptor, the cobalt center behaves as a spin shuttle and the nitrene radical acts as a nucleophile. Such a mechanism for (cobalt catalyzed) nitrene transfer was hitherto unknown and complements the known concerted and stepwise mechanisms for N-group transfer.

scholarly journals Exploiting single-electron transfer in Lewis pairs for catalytic bond-forming reactions

2020 ◽  
Vol 11 (17) ◽  
pp. 4305-4311 ◽  
Author(s):  
Yoshitaka Aramaki ◽  
Naoki Imaizumi ◽  
Mao Hotta ◽  
Jun Kumagai ◽  
Takashi Ooi
Keyword(s):  
Electron Transfer ◽  
Bond Formation ◽  
Ion Pair ◽  
Single Electron ◽  
Single Electron Transfer ◽  
Carbon Bond ◽  
Bond Forming ◽  
Carbon Carbon Bond ◽  
Pair Generation ◽  
Lewis Pairs

Radical–ion pair generation from common Lewis pairs and its application to catalytic carbon–carbon bond formation.

Visible Light-Promoted Photocatalytic C-5 Carboxylation of 8-Aminoquinoline Amides and Sulfonamides via a Single Electron Transfer Pathway

2019 ◽  
Vol 84 (16) ◽  
pp. 9869-9896 ◽  
Author(s):  
Chiranjit Sen ◽  
Tapan Sahoo ◽  
Harshvardhan Singh ◽  
Eringathodi Suresh ◽  
Subhash Chandra Ghosh
Keyword(s):  
Electron Transfer ◽  
Visible Light ◽  
Single Electron ◽  
Single Electron Transfer ◽  
Electron Transfer Pathway
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