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Nobel Prize in Chemistry 2021


Benjamin List (Germany) and David W.C. MacMillan (USA) were announced joint winners of Nobel Prize in Chemistry 2021 “for the development of asymmetric organocatalysis”.

(Image Source: cen.acs.org)

Research

  • The type of catalysis developed independently by Benjamin List and David MacMillan, called organocatalysis, uses small organic molecules that are generally both environmentally friendly and inexpensive to produce. The use of organocatalysts has rapidly expanded since 2000. This is largely due to their ability to drive asymmetric synthesis.
  • List and MacMillan have shown that organic catalysts can be used for a wide range of chemical reactions. Using this approach, researchers can construct anything from new drugs to molecules that can capture light in solar cells.

Work of Benjamin List

  • Many enzymes catalyze chemical reactions without the help of metals. Instead, the reactions are mostly driven by a small number of amino acids in the enzyme. Benjamin List wondered whether amino acids have to be part of an enzyme to catalyze a chemical reaction. He tested whether proline could catalyze an intermolecular aldol reaction—which it did. List showed not only that proline is an efficient catalyst, but also that it can be used in asymmetric catalysis. Compared to metals and enzymes, proline is very simple, cheap, and environmentally friendly.

Work of David MacMillan

  • David MacMillan had worked on improving asymmetric catalysis using metals. However, many metal-based catalysts are easily destroyed by moisture, which hinders their use in large-scale industrial manufacturing. MacMillan developed simple organic molecules that could temporarily provide or accommodate electrons—similar to metals. This was achieved by choosing compounds that can form an iminium ion. He found that a chiral imidazolidinone can catalyze a Diels-Alder reaction between α,β-unsaturated aldehydes and cyclopentadiene in this way. MacMillan coined the term organocatalysis to describe the general method.