Organocatalyzed Birch Reduction Driven by Visible Light

Justin P. Cole; Dian-Feng Chen; Max Kudisch; Ryan M. Pearson; Chern-Hooi Lim; Garret M. Miyake

doi:10.1021/jacs.0c05899

Organocatalyzed Birch Reduction Driven by Visible Light

10.26434/chemrxiv.11860221 ◽

2020 ◽

Author(s):

Justin P. Cole ◽

Dian-Feng Chen ◽

Max Kudisch ◽

Ryan M. Pearson ◽

Chern-Hooi Lim ◽

...

Keyword(s):

Visible Light ◽

Alkali Metals ◽

High Energy ◽

Cryogenic Liquid ◽

Solvated Electrons ◽

Mole Percent ◽

Birch Reduction ◽

Application Potential ◽

Molecular Complexity ◽

High Energy Chemical

<p>The Birch reduction is a powerful synthetic methodology that uses solvated electrons to convert inert arenes to 1,4-cyclohexadienes—valuable intermediates for building molecular complexity. This reaction historically requires dangerous alkali metals and cryogenic liquid ammonia as the solvent, severely limiting application potential and scalability. Here, we introduce benzo[ghi]perylene imides as new organic photoredox catalysts for Birch reductions performed at ambient temperature and driven by visible light. Using low catalyst loadings (<1 mole percent), benzene and other functionalized arenes can be selectively transformed to 1,4-cyclohexadienes in good yields. Mechanistic studies support that this unprecedented visible light induced reactivity is enabled by the ability of the organic photoredox catalyst to harness the energy from two visible light photons to affect a single, high energy chemical transformation, likely proceeding through a solvated electron.</p>

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Organocatalyzed Birch Reduction Driven by Visible Light

10.26434/chemrxiv.11860221.v1 ◽

2020 ◽

Author(s):

Justin P. Cole ◽

Dian-Feng Chen ◽

Max Kudisch ◽

Ryan M. Pearson ◽

Chern-Hooi Lim ◽

...

Keyword(s):

Visible Light ◽

Alkali Metals ◽

High Energy ◽

Cryogenic Liquid ◽

Solvated Electrons ◽

Mole Percent ◽

Birch Reduction ◽

Application Potential ◽

Molecular Complexity ◽

High Energy Chemical

<p>The Birch reduction is a powerful synthetic methodology that uses solvated electrons to convert inert arenes to 1,4-cyclohexadienes—valuable intermediates for building molecular complexity. This reaction historically requires dangerous alkali metals and cryogenic liquid ammonia as the solvent, severely limiting application potential and scalability. Here, we introduce benzo[ghi]perylene imides as new organic photoredox catalysts for Birch reductions performed at ambient temperature and driven by visible light. Using low catalyst loadings (<1 mole percent), benzene and other functionalized arenes can be selectively transformed to 1,4-cyclohexadienes in good yields. Mechanistic studies support that this unprecedented visible light induced reactivity is enabled by the ability of the organic photoredox catalyst to harness the energy from two visible light photons to affect a single, high energy chemical transformation, likely proceeding through a solvated electron.</p>

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Recent advances in visible light-activated radical coupling reactions triggered by (i) ruthenium, (ii) iridium and (iii) organic photoredox agents

Chemical Society Reviews ◽

10.1039/d1cs00311a ◽

2021 ◽

Author(s):

Jonathan D. Bell ◽

John A. Murphy

Keyword(s):

Visible Light ◽

Coupling Reactions ◽

Birch Reduction ◽

Radical Coupling ◽

Recent Advances

Visible light-activated reactions continue to expand and diversify. The example shown here is a Birch reduction achieved by organophotoredox reagents.

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Studies of metaphase chromosomes in the scanning transmission x-ray microscope: Image fidelity, radiation damage and specimen preparation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100129826 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1038-1039

Author(s):

Shawn Williams ◽

Xiaodong Zhang ◽

Susan Lamm ◽

Jack Van’t Hof

Keyword(s):

Visible Light ◽

Radiation Damage ◽

Cross Section ◽

Imaging Techniques ◽

Dose Range ◽

Specimen Preparation ◽

X Rays ◽

Metaphase Chromosomes ◽

X Ray ◽

Scanning Transmission

The Scanning Transmission X-ray Microscope (STXM) is well suited for investigating metaphase chromosome structure. The absorption cross-section of soft x-rays having energies between the carbon and oxygen K edges (284 - 531 eV) is 6 - 9.5 times greater for organic specimens than for water, which permits one to examine unstained, wet biological specimens with resolution superior to that attainable using visible light. The attenuation length of the x-rays is suitable for imaging micron thick specimens without sectioning. This large difference in cross-section yields good specimen contrast, so that fewer soft x-rays than electrons are required to image wet biological specimens at a given resolution. But most imaging techniques delivering better resolution than visible light produce radiation damage. Soft x-rays are known to be very effective in damaging biological specimens. The STXM is constructed to minimize specimen dose, but it is important to measure the actual damage induced as a function of dose in order to determine the dose range within which radiation damage does not compromise image quality.

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Scanning luminescence x-ray microscopy: Progress toward selective staining using microspheres

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100168104 ◽

1994 ◽

Vol 52 ◽

pp. 74-75

Author(s):

C. Jacobsen ◽

J. Fu ◽

S. Mayer ◽

Y. Wang ◽

S. Williams

Keyword(s):

Visible Light ◽

Active Sites ◽

Light Emission ◽

Chinese Hamster ◽

Polystyrene Spheres ◽

Good Resistance ◽

X Ray ◽

Selective Staining ◽

Visible Light Emission ◽

Specific Labelling

In scanning luminescence x-ray microscopy (SLXM), a high resolution x-ray probe is used to excite visible light emission (see Figs. 1 and 2). The technique has been developed with a goal of localizing dye-tagged biochemically active sites and structures at 50 nm resolution in thick, hydrated biological specimens. Following our initial efforts, Moronne et al. have begun to develop probes based on biotinylated terbium; we report here our progress towards using microspheres for tagging.Our initial experiments with microspheres were based on commercially-available carboxyl latex spheres which emitted ~ 5 visible light photons per x-ray absorbed, and which showed good resistance to bleaching under x-ray irradiation. Other work (such as that by Guo et al.) has shown that such spheres can be used for a variety of specific labelling applications. Our first efforts have been aimed at labelling ƒ actin in Chinese hamster ovarian (CHO) cells. By using a detergent/fixative protocol to load spheres into cells with permeabilized membranes and preserved morphology, we have succeeded in using commercial dye-loaded, spreptavidin-coated 0.03μm polystyrene spheres linked to biotin phalloidon to label f actin (see Fig. 3).

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Photocatalyst-free decarboxylative aminoalkylation of imidazo[1,2-a]pyridines with N-aryl glycines enabled by visible light

Organic Chemistry Frontiers ◽

10.1039/c9qo00935c ◽

2019 ◽

Vol 6 (21) ◽

pp. 3693-3697 ◽

Cited By ~ 11

Author(s):

Jiu-Jian Ji ◽

Zhi-Qiang Zhu ◽

Li-Jin Xiao ◽

Dong Guo ◽

Xiao Zhu ◽

...

Keyword(s):

Visible Light

A novel, green and efficient visible-light-promoted decarboxylative aminoalkylation reaction of imidazo[1,2-a]pyridines with N-aryl glycines has been described.

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