The Royal Swedish Academy of Sciences awarded the 2021 Nobel Prize in Chemistry to Benjamin List and David W.C. MacMillan "for the development of asymmetric organocatalysis." The prize amount was 10 million Swedish kronor, shared equally between the laureates.
Asymmetric Organocatalysis: The 2021 Nobel Prize in Chemistry
Abstract: The 2021 Nobel Prize in Chemistry was awarded to Benjamin List and David W.C. MacMillan for the development of asymmetric organocatalysis, a precise tool for molecular construction based on small organic molecules. This article summarizes the scientific basis of the award and its significance.
1. The Prize
2. The Scientific Problem
Building molecules requires catalysts—substances that accelerate chemical reactions without being consumed. Before 2000, researchers recognized only two categories of catalysts: metals and enzymes. Metal catalysts often require carefully maintained, energy-intensive conditions and can be harmful to the environment; enzymes are large, complex biomolecules. A third option was not considered feasible.
3. The Discovery
In 2000, List and MacMillan independently demonstrated that small organic molecules could function as efficient asymmetric catalysts. List used proline to catalyze an aldol reaction; MacMillan developed iminium-based catalysts for Diels–Alder reactions. MacMillan coined the term "organocatalysis" for this concept. The Nobel Committee described the concept as "as simple as it is ingenious," noting that many had wondered why it was not discovered earlier.
4. Why It Matters
The significance lies in two properties: accessibility and asymmetry. Organic catalysts are built on stable carbon frameworks with common elements such as oxygen, nitrogen, sulfur, or phosphorus, making them cheap and environmentally friendly to produce. More importantly, they enable asymmetric catalysis—the selective formation of one mirror-image molecule over another. This is critical for pharmaceutical research, where the two mirror images of a molecule (enantiomers) can have drastically different biological effects.
5. Conclusion
The 2021 Nobel Prize recognized a fundamental shift in how chemists approach molecular construction. By demonstrating that small organic molecules could serve as a third pillar of catalysis alongside metals and enzymes, List and MacMillan provided a precise, accessible, and environmentally benign tool for building the molecules that underpin modern science.