The Chemical Conundrum

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The Abstract will feature every-other-weekly posts from three undergraduate students who are doing research at McGill. This is the first post in the first of those series. Stay tuned for introductions from our other regular bloggers next week!

Hello fellow Abstract readers!

I’m Isabella Liu, a fourth year Chemistry student. I completed my honours project last summer and am currently continuing said project. I am working in the green chemistry laboratory in the Otto Maass building – basically, look up to the fourth floor,  and that’s where you’ll find me working two days a week under the supervision of Professor C.-J. Li. (In the photo above, Dr. Li is on the very left. I’m the one in pink!).

In my lab, we search for greener and more atom-efficient methodologies to replace the reactions that you’re learning in your organic chemistry courses. What I do is search for green methods of C–C bond formation, an essential task in constructing organic molecules.

Historically, C–C bond coupling has only been possible if functional groups were attached to the coupling carbons (pathway 1). An example of that would be a Grignard reaction – something that should be very familiar to people who’ve taken Organic Chemistry 2!   However, reactions that require functional groups have low atom economy (which means not 100% of your reactants are converted into your product, a.k.a. you have undesired products in your reaction). This type of C–C bond coupling requires the pre-functionalization of C–H bonds, which is time consuming. Since the use of functional groups  is not green, we use metal catalysts to activate the C—H bonds. This technique is called Cross-Dehydrogenative Coupling (CDC), and was actually developed by my supervisor! CDC reactions allow chemists to skip the pre-functionalization step (pathway 2).  The advantages of this type of reactions include: (i) fewer synthetic steps; (ii) higher atom economy; (iii) less toxic waste; and (iv)the ability to use safer and cheaper starting materials.

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What I did over the summer was an optimization process for the coupling of isochroman and dimethylmalonate. This reaction produces an enantiomer, which means the products are mirror images of each other (like your hand!). We are interested in enantioselective coupling reactions due to their potential pharmaceutical applications (many drugs only work properly if they are a specific enantiomer, – if the drug is “left-handed”, so to speak, instead of “right-handed”, it won’t work). Over the summer, we’ve optimized it using a chiral ligand, L*82, catalysing the reaction with Cu (I), which gave us a pretty good enantiomeric excess value (measures how much of a particular enantiomer we can get). Over the course of the semester, I’ll update you on my project as well as the little anecdotes of what it’s like working in an organic chemistry lab.

It was nice meeting you all, hope you enjoy the blog!

Isabella

(Photo credit: Ping Wang, a visiting scientist)

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