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Photochemical Reaction Discovery

photochemIf you want to see some folks who are really blasting away with a photochemistry setup, check out this paper from Boston University (Aaron Beeler and John Porco’s groups). They have a 1000-watt high-pressure mercury lamp going, with appropriate filters (with that sort of light flux, you have a lot of spectral windows to choose from).
They’re using this setup in both batch and flow mode to do reaction discovery – picking out starting materials with appropriate chromphores and seeing that what they get when they irradiate them under different conditions (solvent, sensitizers, residence time and so on). From my own photochemical experiences, I can assume that the results will provide plenty of material to work on – these sorts of reactions can take drastically different courses all of a sudden. The time-intensive step is not doubt the part where you figure out what the heck happened.
The scheme shown is representative – the top product is a photo-Fries rearrangement, while the bottom one is clearly a 2+2 and some sort of sulfonyl migration. There are vast unexplored swaths of territory (both in reaction space and chemical space) to be found in photochemistry, and I look forward to seeing more weird things come out of this setup.

12 comments on “Photochemical Reaction Discovery”

  1. milkshake says:

    For a synthetic organic chemist, UV-photochemistry has about the same “activation barrier” as electrochemistry. And scaling up is a bitch.

  2. pbhomeboy says:

    Not necessarily so. New systems from companies like vapourtec make it actually really easy to scale up photochemistry experiments. I have run >50g overnight batches using photochemistry and flow.

  3. MA says:

    Worked with this group my senior year at BU (on an unrelated project). Great group of people and scientists.
    @1, my project involved exactly that. Not necessarily difficult from a process stand point, very amenable to flow chemistry.

  4. Anonymous says:

    @1 Please check out this photochemical reaction performed in 600kg scale. With a big plus it is employed for the synthesis of the highly complex natural product – artemisinin. Do not be afraid of problems. As chemists we are trained to solve problems.
    http://pubs.acs.org/doi/abs/10.1021/op4003196

  5. Anonymous says:

    thumbs up to @ 2, 3, and 4!

  6. Nick K says:

    #4: Very impressive work. I’m looking forward to seeing more large-scale photochemistry.

  7. Anonymous says:

    Big pharma have been investing in photochemistry in flow for years. I am a med chemist and I use photochemistry in flow to gerante new cores/bulk building blocks for med chem programs scale is no longer an issue if you are not using flow photochemistry you are falling behind, electrochemistry is the next challange to scale.
    Over view who’s doing what:-
    Vertex: Uniqsis FlowSyn to generate photochemical libraries.
    Roche: in-house designed photochemical equipment and publishing on novel scaffolds; Collaborated with Thorsten Bach.
    Novartis: in-house designed photochemical equipment.
    Pfizer: had a photochemistry group at Sandwich, UK.
    Abbott Laboratories: in-house designed photochemical equipment Lophtor®.
    Sanofi-Aventis: produced 35 tons of Artemisinin in 2013 & plans to produce 50 to 60 tons in 2014 photochemically at its Italian manufacturing site at Garessio.
    Companies cited for their interest in photochemical synthesis without divulging details of their actives AZ, BASF, Bayer, Bristol Myers Squibb, Clariant & GSK.

  8. simpl re #4 says:

    Great progress on artemisinin, especially for a not-for-profit launch.
    The WHO list referred to in the article is interesting (linked to my handle).
    Firstly, the WHO has also made progress, though their priorities differ markedly from R&D Pharma who are present with one or two substances, if at all.
    Secondly, they are using FDA reviews to recommend for international use, even if the product is tied up for the US market by US patent protection.

  9. marta says:

    Didn’t anyone notice that Scheme 1 and Scheme 2 are exactly the same even though they are supposed to be describing 2 different mechanisms? That is probably why they are referencing compounds in the paper that we don’t see anywhere but the experimentals, including a reaction scheme not described.

  10. Anonymous says:

    Vapourtec have shown a range of photochemical applications with their UV-150 in collaboration with a couple of research groups very active in this area. This looks very promising with excellent wavelength filtering and single wavelength LEDs available. This might be an easy way to overcome the ‘activation energy’.

  11. Anonymous says:

    Vapourtec have shown a range of photochemical applications with their UV-150 in collaboration with a couple of research groups very active in this area. This looks very promising with excellent wavelength filtering and single wavelength LEDs available. This might be an easy way to overcome the ‘activation energy’.

  12. Anonymous says:

    Oops, I only meant to post once.

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