scholarly journals Investigations on the 1,2-Hydrogen Atom Transfer Reactivity of Alkoxyl Radicals under Visible-Light-Induced Reaction Conditions

Synlett ◽  
2020 ◽  
Author(s):  
Yiyun Chen ◽  
Dan Liu ◽  
Jing Zhang
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Atom ◽  
Visible Light ◽  
Organic Synthesis ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Reaction Conditions ◽  
Alkoxyl Radical ◽  
Induced Reaction ◽  
Key Questions

AbstractThe alkoxyl radicals have demonstrated superior hydrogen atom transfer reactivity in organic synthesis due to the strong oxygen–hydrogen bond dissociation energy. However, only the intermolecular hydrogen atom transfer (HAT) and intramolecular 1,5-HAT have been widely studied and synthetically utilized for C(sp3)–H functionalization. This Account summarizes our investigations on the unusual 1,2-HAT reactivity of alkoxyl radicals under visible-light-induced reaction conditions for the α-C–H functionalization. Various mechanistic investigations were discussed in this Account to address three key questions to validate the 1,2-HAT reactivity of alkoxyl radicals.1 Introduction2 Could Aldehydes/Ketones Be the Sole Reaction Intermediate for the α-C–H Allylation? NO3 Is the Alkoxyl Radical Absolutely Involved in the Reaction? YES4 Does the 1,2-HAT of Alkoxyl Radicals Irrefutably Exist? YES5 Conclusion

1.9 Oxygen-Centered Radicals

2021 ◽  
Author(s):  
J. Zhang ◽  
D. Liu ◽  
Y. Chen
Keyword(s):  
Hydrogen Atom ◽  
Visible Light ◽  
Organic Synthesis ◽  
Reactive Intermediates ◽  
Radical Addition ◽  
Hydrogen Atom Transfer ◽  
Reaction Conditions ◽  
Recent Advances ◽  
Carbon Carbon Bonds ◽  
Induced Reaction

AbstractOxygen-centered radicals (R1O•) are reactive intermediates in organic synthesis, with versatile synthetic utilities in processes such as hydrogen-atom transfer (HAT), β-fragmentation, radical addition to unsaturated carbon–carbon bonds, and rearrangement reactions. In this review, we focus on recent advances in the generation and transformation of oxygen-centered radicals, including (alkyl-, α-oxo-, aryl-) carboxyl, alkoxyl, aminoxyl, phenoxyl, and vinyloxyl radicals, and compare the reactivity of oxygen-centered radicals under traditional reaction conditions with their reactivity under visible-light-induced reaction conditions.

Direct Cyclization of Alkenyl Thioester via Transition Metal‐hydrogen Atom Transfer/radical‐polar Crossover Mechanism

2019 ◽  
Author(s):  
Shiori Date ◽  
Kensei Hamasaki ◽  
Karen Sunagawa ◽  
Hiroki Koyama ◽  
Chikayoshi Sebe ◽  
...  
Keyword(s):  
Natural Products ◽  
Hydrogen Atom ◽  
Transition Metal ◽  
Hydrogen Atom Transfer ◽  
Synthetic Method ◽  
Atom Transfer ◽  
Reaction Conditions ◽  
Hydride Hydrogen ◽  
Sulfur Heterocycles ◽  
One Step

<div>We report here a catalytic, Markovnikov selective, and scalable synthetic method for the synthesis of saturated sulfur heterocycles, which are found in the structures of pharmaceuticals and natural products, in one step from an alkenyl thioester. Unlike a potentially labile alkenyl thiol, an alkenyl thioester is stable and easy to prepare. The powerful Co catalysis via a cobalt hydride hydrogen atom transfer and radical-polar crossover mechanism enabled simultaneous cyclization and deprotection. The substrate scope was expanded by the extensive optimization of the reaction conditions and tuning of the thioester unit.</div>

Visible light photoredox-catalysed remote C–H functionalisation enabled by 1,5-hydrogen atom transfer (1,5-HAT)

2021 ◽  
Author(s):  
Weisi Guo ◽  
Qian Wang ◽  
Jieping Zhu
Keyword(s):  
Hydrogen Atom ◽  
Visible Light ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer

The generation of heteroatom-centred radicals followed by intramolecular 1,5-HAT and functionalisation of the translocated carbon-centred radical is an efficient way to functionalize chemo- and regio-selectively the remote unactivated C(sp3)–H bond.

Carbonylative Coupling of Simple Alkanes and Alkenes Enabled by Organic Photoredox Catalysis

2021 ◽  
Author(s):  
Ling Chen ◽  
Jing Hou ◽  
Ming Zheng ◽  
Le-Wu Zhan ◽  
Wan-Ying Tang ◽  
...  
Keyword(s):  
Hydrogen Atom ◽  
Visible Light ◽  
Transfer Process ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Photoredox Catalysis ◽  
Visible Light Driven

A visible-light-driven direct carbonylative coupling of simple alkanes and alkenes via the combination of the hydrogen atom transfer process and photoredox catalysis has been demonstrated. Employing the N-alkoxyazinium salt as...

scholarly journals Dual Cobalt and Photoredox Catalysis Enabled Intermolecular Oxidative Hydrofunctionalization

2020 ◽  
Author(s):  
Han-Li Sun ◽  
Fan Yang ◽  
Wei-Ting Ye ◽  
Jun-Jie Wang ◽  
Rong Zhu
Keyword(s):  
Hydrogen Atom ◽  
Visible Light ◽  
Electrochemical Analysis ◽  
Hydrogen Atom Transfer ◽  
Redox Process ◽  
Photochemical Oxidation ◽  
Atom Transfer ◽  
Photoredox Catalysis ◽  
Wide Range ◽  
Selective Alkylation

A general protocol has been developed for the Markovnikov-selective intermolecular hydrofunctionalization based on visible-light-mediated Co/Ru dual catalysis. The key feature involves the photochemical oxidation of an organocobalt(III) intermediate derived from hydrogen atom transfer, which is supported by electrochemical analysis, quenching studies and stoichiometric experiments. This unique redox process enables the efficient branch-selective alkylation of pharmaceutically important nucleophiles (phenols, sulfonamides and various N-heterocycles) using a wide range of alkenes including moderately electron-deficient ones. Moreover, light-gated polar functionalization via organocobalt species was demonstrated.

Iminyl Radical-Triggered 1,5-Hydrogen-Atom Transfer/Heck-Type Coupling by Visible-Light Photoredox Catalysis

2019 ◽  
Vol 84 (10) ◽  
pp. 6475-6482 ◽  
Author(s):  
Li Chen ◽  
Li-Na Guo ◽  
Zhi-Yong Ma ◽  
Yu-Rui Gu ◽  
Junjie Zhang ◽  
...  
Keyword(s):  
Hydrogen Atom ◽  
Visible Light ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Photoredox Catalysis ◽  
Type Coupling

Benzylic C–H heteroarylation of N-(benzyloxy)phthalimides with cyanopyridines enabled by photoredox 1,2-hydrogen atom transfer

2020 ◽  
Vol 56 (61) ◽  
pp. 8671-8674
Author(s):  
Long-Jin Zhong ◽  
Hong-Yu Wang ◽  
Xuan-Hui Ouyang ◽  
Jin-Heng Li ◽  
De-Lie An
Keyword(s):  
Hydrogen Atom ◽  
Visible Light ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer

Visible light initiated α-C(sp3)–H hetroarylation of N-(benzyloxy)phthalimides with cyanopyridines via 1,2-hydrogen atom transfer is depicted.

Microsolvation, hydrogen bond dynamics and excited state hydrogen atom transfer mechanism of 2′,4′-dihydroxychalcone

2020 ◽  
Vol 739 ◽  
pp. 137030
Author(s):  
Yelechakanahalli Lingaraju Ramu ◽  
Kandigowda Jagadeesha ◽  
Tavarekere Shivalingaswamy ◽  
Mariyappa Ramegowda
Keyword(s):  
Hydrogen Bond ◽  
Excited State ◽  
Hydrogen Atom ◽  
Hydrogen Atom Transfer ◽  
Transfer Mechanism ◽  
Atom Transfer ◽  
Hydrogen Bond Dynamics

scholarly journals Photo-triggered hydrogen atom transfer from an iridium hydride complex to unactivated olefins

2020 ◽  
Vol 11 (32) ◽  
pp. 8582-8594
Author(s):  
Mirjam R. Schreier ◽  
Björn Pfund ◽  
Xingwei Guo ◽  
Oliver S. Wenger
Keyword(s):  
Hydrogen Atom ◽  
Visible Light ◽  
Electron Donor ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Hydride Complex ◽  
Proton Source

Upon irradiation with visible light, an iridium hydride complex undergoes hydrogen atom transfer (HAT) to unactivated olefins in presence of a sacrificial electron donor and a proton source.

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