Stefan Howorka

Nobel Prize in Chemistry for Bio-Inspired Catalysts

The Nobel Prize in Chemistry in 2021 has been awarded to German Benjamin List and British David MacMillan.
Prof Stefan Howorka from the ISMB at UCL Chemistry explains: ‘The two researchers have developed a new class of catalysts that are inspired by Nature. Enzymes are widely used in biology as they initiate and specifically control biochemical reactions to achieve the desired stereochemistry while limiting the creation of undesirable by-products. Reconstructing these catalytic functions with smaller and cheaper synthetic units is of considerable scientific and industrial interest. Ideally, synthetic catalysts should also avoid precious metals such as platinum which are not environmentally friendly.
List and MacMillan succeeded independently of each other in developing efficient biomimetic and “green” catalysts. In the late 1990s, List wondered whether amino acids found in the enzymes’ active site would also be able to achieve part of the same catalytic role if added in isolation. As proof-of-principle, List tested the catalytic properties of proline and related compounds in an aldol reaction. The specific question was whether the use of a chiral proline would control the stereochemical outcome of the reaction. Indeed, the chirality of the catalyst controlled which enantiomer of the aldol products was formed.
MacMillan was working in the same field. MacMillan was motivated to develop new catalysts that avoid the widely used metals. Rather, he focused on environmentally harmless and inexpensive organic frameworks that contain -in addition to carbon- oxygen, nitrogen, sulphur or phosphorous. Similar to List, MacMillan also tested chiral versions of his organic catalysts but with a different reaction, the Diels-Alder cycloaddition. The reaction was successful as enantiopure products formed depending on the chirality of the catalysts.
Reflecting the catalysts’ composition and enantioselective control, MacMillan coined the term ‘asymmetric organocatalysis’ This new field has grown dramatically and develops simple, easy-to-manufacture and environmentally friendly catalyst. This has a huge impact in science and industry to produce new pharmaceuticals or molecules that can capture light in solar cells. This year’s Nobel prize and the Nobel prize given in 2018 for ‘the directed evolution of enzymes’ underscore the importance of developing new catalytic tools, Prof Howorka concludes.

References:
J. Am. Chem. Soc. 2000, 122, 2395-2396; J. Am. Chem. Soc. 2000, 122, 4243-4244

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