Unified View of Oxidative C–H Bond Cleavage and Sulfoxidation by a Nonheme Iron(IV)–Oxo Complex via Lewis Acid-Promoted Electron Transfer

2014 ◽  
Vol 53 (7) ◽  
pp. 3618-3628 ◽  
Author(s):  
Jiyun Park ◽  
Yuma Morimoto ◽  
Yong-Min Lee ◽  
Wonwoo Nam ◽  
Shunichi Fukuzumi
Keyword(s):  
Electron Transfer ◽  
Lewis Acid ◽  
Bond Cleavage ◽  
Nonheme Iron ◽  
Unified View

scholarly journals Light-Driven Depolymerization of Native Lignin Enabled by Proton- Coupled Electron Transfer

2019 ◽  
Author(s):  
Suong Nguyen ◽  
Phillip Murray ◽  
Robert Knowles
Keyword(s):  
Electron Transfer ◽  
Visible Light ◽  
Bond Cleavage ◽  
Direct Conversion ◽  
Alkoxy Radical ◽  
Radical Intermediate ◽  
Polymer Backbone ◽  
Good Efficiency ◽  
Chemical Reagents ◽  
Proton Coupled Electron Transfer

<div><p>Here we report a catalytic, light-driven method for the redox-neutral depolymerization of native lignin biomass at ambient temperature. This transformation proceeds via a proton-coupled electron-transfer (PCET) activation of an alcohol O–H bond to generate a key alkoxy radical intermediate, which then drives the <i>β</i>-scission of a vicinal C–C bond. Notably, this depolymerization is driven solely by visible light irradiation, requiring no stoichiometric chemical reagents and producing no stoichiometric waste. This method exhibits good efficiency and excellent selectivity for the activation and fragmentation of <i>β</i>-O-4 linkages in the polymer backbone, even in the presence of numerous other PCET-active functional groups. DFT analysis suggests that the key C–C bond cleavage reactions produce non-equilibrium product distributions, driven by excited-state redox events. These results provide further evidence that visible-light photocatalysis can serve as a viable method for the direct conversion of lignin biomass into valuable arene feedstocks.</p></div>

scholarly journals Selective C-N σ Bond Cleavage in Azetidinyl Amides under Transition Metal-Free Conditions

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 459 ◽  
Author(s):  
Hengzhao Li ◽  
Zemin Lai ◽  
Adila Adijiang ◽  
Hongye Zhao ◽  
Jie An
Keyword(s):  
Electron Transfer ◽  
Transition Metal ◽  
Transfer Reaction ◽  
Bond Cleavage ◽  
Electron Transfer Reaction ◽  
Amide Bond ◽  
Single Electron Transfer ◽  
Reaction Conditions ◽  
Metal Free ◽  
Single Electron Transfer Reaction

Functionalization of amide bond via the cleavage of a non-carbonyl, C-N σ bond remains under-investigated. In this work, a transition-metal-free single-electron transfer reaction has been developed for the C-N σ bond cleavage of N-acylazetidines using the electride derived from sodium dispersions and 15-crown-5. Of note, less strained cyclic amides and acyclic amides are stable under the reaction conditions, which features the excellent chemoselectivity of the reaction. This method is amenable to a range of unhindered and sterically encumbered azetidinyl amides.

Properties and reactivities of nonheme iron(iv)–oxo versus iron(v)–oxo: long-range electron transfer versus hydrogen atom abstraction

2014 ◽  
Vol 16 (41) ◽  
pp. 22611-22622 ◽  
Author(s):  
Baharan Karamzadeh ◽  
Devendra Singh ◽  
Wonwoo Nam ◽  
Devesh Kumar ◽  
Sam P. de Visser
Keyword(s):  
Electron Transfer ◽  
Hydrogen Atom ◽  
Long Range ◽  
Cation Radical ◽  
Nonheme Iron ◽  
Hydrogen Atom Abstraction ◽  
Computational Studies ◽  
Radical Species ◽  
Oxo Ligand

Computational studies show that the perceived nonheme iron(v)–oxo is actually an iron(iv)–oxo ligand cation radical species.

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