Asymmetric alkylation of remote C(sp3)–H bonds by combining proton-coupled electron transfer with chiral Lewis acid catalysis

2017 ◽  
Vol 53 (64) ◽  
pp. 8964-8967 ◽  
Author(s):  
Wei Yuan ◽  
Zijun Zhou ◽  
Lei Gong ◽  
Eric Meggers
Keyword(s):  
Electron Transfer ◽  
Hydrogen Atom ◽  
Visible Light ◽  
Lewis Acid ◽  
Acid Catalysis ◽  
Hydrogen Atom Transfer ◽  
Lewis Acid Catalysis ◽  
Asymmetric Alkylation ◽  
Proton Coupled Electron Transfer ◽  
Chiral Lewis Acid

The catalytic asymmetric alkylation of the remote, unactivated δ-position of N-alkyl amides was enabled by the combination of visible-light-induced proton-coupled electron transfer, 1,5-hydrogen atom transfer, and chiral Lewis acid catalysis.

scholarly journals Evaluation of excited state bond weakening for ammonia synthesis from a manganese nitride: stepwise proton coupled electron transfer is preferred over hydrogen atom transfer

2019 ◽  
Vol 55 (39) ◽  
pp. 5595-5598 ◽  
Author(s):  
Florian Loose ◽  
Dian Wang ◽  
Lei Tian ◽  
Gregory D. Scholes ◽  
Robert R. Knowles ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Hydrogen Atom ◽  
Visible Light ◽  
Driving Force ◽  
Ammonia Synthesis ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Proton Coupled Electron Transfer ◽  
Manganese Nitride

Concepts for the thermodynamically challenging synthesis of weak N–H bonds by photoinduced proton coupled electron transfer are explored. By harvesting visible light as driving force, ammonia synthesis was achieved and mechanistically elucidated.

Chiral Lewis Acid Catalysis in Nitrile Oxide Cycloadditions

2004 ◽  
Vol 126 (17) ◽  
pp. 5366-5367 ◽  
Author(s):  
Mukund P. Sibi ◽  
Kennosuke Itoh ◽  
Craig P. Jasperse
Keyword(s):  
Lewis Acid ◽  
Acid Catalysis ◽  
Nitrile Oxide ◽  
Lewis Acid Catalysis ◽  
Chiral Lewis Acid

Atmospheric formation of the NO3 radical from gas-phase reaction of HNO3 acid with the NH2 radical: proton-coupled electron-transfer versus hydrogen atom transfer mechanisms

2014 ◽  
Vol 16 (36) ◽  
pp. 19437-19445 ◽  
Author(s):  
Josep M. Anglada ◽  
Santiago Olivella ◽  
Albert Solé
Keyword(s):  
Electron Transfer ◽  
Hydrogen Atom ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Phase Reaction ◽  
Electron Transfer Mechanism ◽  
Proton Coupled Electron Transfer ◽  
No3 Radical ◽  
Transfer Mechanisms ◽  
Atmospheric Formation

The amidogen radical abstracts the hydrogen from nitric acid through a proton coupled electron transfer mechanism rather than by an hydrogen atom transfer process.

scholarly journals Light-driven deracemization enabled by excited-state electron transfer

Science ◽  
2019 ◽  
Vol 366 (6463) ◽  
pp. 364-369 ◽  
Author(s):  
Nick Y. Shin ◽  
Jonathan M. Ryss ◽  
Xin Zhang ◽  
Scott J. Miller ◽  
Robert R. Knowles
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Hydrogen Atom ◽  
Visible Light ◽  
Asymmetric Synthesis ◽  
Hydrogen Atom Transfer ◽  
Product Distributions ◽  
Reaction Proceeds ◽  
Molecular Catalysts ◽  
Distinct Approach

Deracemization is an attractive strategy for asymmetric synthesis, but intrinsic energetic challenges have limited its development. Here, we report a deracemization method in which amine derivatives undergo spontaneous optical enrichment upon exposure to visible light in the presence of three distinct molecular catalysts. Initiated by an excited-state iridium chromophore, this reaction proceeds through a sequence of favorable electron, proton, and hydrogen-atom transfer steps that serve to break and reform a stereogenic C–H bond. The enantioselectivity in these reactions is jointly determined by two independent stereoselective steps that occur in sequence within the catalytic cycle, giving rise to a composite selectivity that is higher than that of either step individually. These reactions represent a distinct approach to creating out-of-equilibrium product distributions between substrate enantiomers using excited-state redox events.

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