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Utilization of Stop-flow Micro-tubing Reactors for the Development of Organic Transformations
Published on: January 4, 2018
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Organic Synthesis Away from Equilibrium: Contrathermodynamic Transformations Enabled by Excited-State Electron
Angela Lin1, Sumin Lee1, Robert R Knowles1
1Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.
Accounts of Chemical Research
|June 21, 2024
Summary
Visible light photoredox catalysis drives organic synthesis using excited-state electron transfer (ET) to achieve challenging transformations. This approach enables contrathermodynamic reactions and unique selectivity, expanding synthetic possibilities beyond conventional methods.
Area of Science:
- Organic Chemistry
- Photochemistry
- Catalysis
Background:
- Biological photosynthesis inspires chemists to use light-driven electron transfer (ET) for energy conversion.
- Adapting light-driven charge transfer for organic synthesis offers potential for novel transformations and selectivities.
- Conventional thermal chemistry faces limitations in achieving certain uphill reactions and specific selectivities.
Purpose of the Study:
- To highlight the application of visible light photoredox catalysis in driving organic transformations away from equilibrium.
- To showcase methods addressing long-standing synthetic challenges using excited-state ET.
- To demonstrate photon-driven, redox-neutral reactions accessing non-equilibrium product distributions.
Main Methods:
- Utilizing excited-state electron transfer (ET) with iridium(III) photocatalysts for anti-Markovnikov hydroamination.
- Employing excited-state proton-coupled electron transfer (PCET) for light-driven C-C bond cleavage in alcohols.
- Cooperative photoredox and chromium(II) catalysis for contrathermodynamic olefin isomerization.
- Visible light irradiation with chiral catalysts for light-driven deracemization of urea substrates.
Main Results:
- Developed general methods for catalytic anti-Markovnikov hydroamination of unactivated alkenes.
- Achieved light-driven C-C bond cleavage in alcohols, leading to isomeric carbonyl products and polymer depolymerization.
- Enabled contrathermodynamic positional isomerization of olefins, accessing less stable isomers.
- Demonstrated efficient light-driven deracemization of a racemic urea substrate with high enantioselectivity.
Conclusions:
- Excited-state ET events are powerful tools for accessing non-equilibrium product distributions in organic synthesis.
- Visible light photoredox catalysis provides unique solutions for challenging synthetic problems.
- Photons serve as the sole stoichiometric reagent in these versatile catalytic transformations.
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