I obtained my PhD under the supervision of Prof. Benjamin List from 2005 to 2008. My professor went on to win the Nobel Prize in Chemistry for 2021 alongside Prof David WC MacMillan in asymmetric catalysis.
When the announcement about the Nobel Prize was made, I was at the Howrah Station waiting to board a train. Suddenly, I started receiving several phone calls and this information about the Nobel Prize was shared on WhatsApp.
I was ecstatic that my PhD supervisor Ben is a Nobel Laureate now. I congratulated him and cherished the memorable time I have spent with him especially during his trip to IIT Guwahati in 2018.
fond memories
After going to the Max-Planck Institute for Kohlenforschung, Muelheim a der Ruhr, Germany in 2005, I was overwhelmed by the excellent facilities there and also fortunate to get Ben as my PhD guide.
He was a down-to-earth person and I was free to discuss any topic with him. He told me that he visited India a long time ago when he was a kid and he liked India very much.
He used to practice yoga and was fascinated with the Indian culture and also liked Indian food very much. I heard that his wife used to cook Indian food in their home.
We used to have boat trips every year and I remember that he used to interact with us wholeheartedly. At times, I used to dive from the boat to swim in the sea.
We also used to have an annual soccer competition every year and he was part of our team. I have encouraged us to play well and once, we even won the trophy.
Professor and Nobel Laureate Benjamin List at IIT Guwahati
Professor Benjamin’s IIT Guwahati visit
In 2018, when he visited IIT Guwahati, I learned ta hat he had turned vegetarian. He ate vegetarian dishes in our quarters and enjoyed the food very much.
I have interacted with the faculty and students of our department separately and it was a pleasant experience.
I have stayed in our guesthouse at IIT Guwahati. I was worried whether everything was ok there and in reply, he told me that he could adjust to any atmosphere and then called himself a “global man”.
He also visited the Kamakhya temple and got interested to know the history of the Devi Kamakhya.
Why did Prof Benjamin List win the Chemistry Nobel?
Prof Benjamin List shared the Chemistry Nobel 2021 with Prof David WC MacMillan for his work in asymmetric catalysis.
Asymmetric synthesis or enantioselective synthesis is a key process in modern chemistry and is particularly important in the field of pharmaceuticals, as different enantiomers or diastereomers of a molecule, considered as mirror images, often have different biological activity.
The term ‘asymmetric’ means lack of equality or equivalence between parts or aspects of something. That something could be anything like nature, chiral molecule or human body.
For example, oranges and lemons smell different, being the left- and right-handed version of the same molecule ie they are the enantiomeric form of Limonene.
If enantiomers are chemically identical, how is it possible that we can distinguish them with our noses?
Enantiomers are identical until they are placed in a chiral environment. Synthesis which favors the formation of one stereoisomer (enantiomer or diastereomer) over another is known as asymmetric synthesis.
When designing small molecules to interact with these targets, one should consider stereoselectivity. Proteins are often enantioselective towards their binding partners.
As considerations for exploring structure space evolve, chirality is increasingly important. Binding affinity for a chiral drug can differ for diastereomers and between enantiomers.
Chemists will attempt synthesis and modification of the promising compounds in order to perform structure-activity relationship (SAR) analysis around the compound’s scaffold to optimize the compound for desired characteristics, while minimizing detrimental aspects.
Asymmetric catalysis is a type of catalysis in which a chiral catalyst directs the formation of a chiral compound such that formation of one particular stereoisomer is favoured.
Since the catalyst is not consumed in this process it may be used in a sub-stoichiometric quantity potentially improving efficiency and avoiding waste.
There were two types of catalysis- enzyme and metal catalysis. In 2000, Ben came up with a third type of catalysis which is asymmetric ‘organocatalysis’ with small organic molecules.
He wanted to design small organic molecules that can act as a catalyst which was then an unknown territory. What was known of the aldose enzyme, whose antibody analog Ben knows by heart during his work at Scripps, was the amino group and acid which was located at the active center.
Ben noticed in a reaction the namely Hajos-Parrish-Eder-Sauer-Wiechert reaction, the amino acid proline had been successfully used as a catalyst. Ben thought, what if proline worked with a similar mechanism like the enzyme in the aldol reaction.
Surprisingly, I have found that the amino acid proline is an effective asymmetric catalyst for the direct aldol reaction between unmodified acetone and a variety of aldehydes which was published in JACS, 2000.
Later, MacMillan used an amino acid analog as organocatalyst to perform asymmetric Diels-Alder reaction which proved to the world that small organic molecules can be used for asymmetric synthesis and gave a new era known as ‘Organocatalysis’.
Ben often reminisces that he achieved “something big” after getting success in the proline catalyzed aldol reaction. Thomson Reuters predicted his name as Nobel laureate in 2010.
I was also asked many times the if the ‘Organocatalysis’ field would win a Nobel Prize. I crossed my fingers and am now, I am happy that my anticipation was correct.
In the last 22 years, this field has progressed enormously and a good number of scientists all over the world are actively involved. Now getting “>99% ee” is not difficult as we have access to different types of organocatalysts. We can prepare a diverse range of molecules with these catalysts.
This field allows us a huge direct benefit in the production of pharmaceutical intermediates when compared with (transition) metal catalysts. Unlike enzymatic and metal catalysis, organocatalysis includes their lack of sensitivity to moisture and oxygen, their ready availability, low cost, and low toxicity.
This concept for catalysis is as simple as it is ingenious, and the fact is that many people have wondered why we didn’t think of it earlier.
Now, Ben is thinking about catalytic drugs: monoclonal antibodies armed with a catalyst that bond to cancer cells and convert a non-toxic active substance into a toxic drug only when it actually arrives at the tumor.
– Article by Prof Subhas Chandra Pan, FRSC, Department of Chemistry, IIT Guwahati
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