Nordic Life Science 1
A “chiral” molecule is one that is not superposab
le with its mirror image. Like left and right hands that have a thumb, fingers in the same order, but are mirror images and not the same, chiral molecules have the same things attached in the same order, but are mirror images and not the same. sually scientists only want one of these. In short, as MacMillan described in his Nobel lecture, asymmetric catalysis could be described as the science of making molecules as one mirror image instead of the other. Before scientists were able to perform asymmetric catalysis, many medicines contained both mirror images of a molecule. One was active and the other could sometimes give unwanted effects. A terrible example of this is the thalidomide catastrophe in the 1960s. The drug thalidomine was approved in the 1950s for a number of indications including morning sickness and anxiety, and it was prescribed to women all around the world. However, one of the mirror molecules in the medicine was found to cause serious deformities in thousands of developing human embryos. Children around the world were born with a range of severe deformities, including phocomelia (a condition that involves malformations of human arms and legs), and many women had miscarriages. It is not known exactly how many worldwide victims there were, although estimates range from 10,000 to 20,000. Another example of two mirror images of a molecule with very different effects is L-DOPA and D-DOPA. L-DOPA is used for the treatment of Parkinson’s disease while D-DOPA can decrease the white blood cell count of a patient and lead to an increased risk of infection. By using asymmetric organocatalysis scientists today can much more easily produce large volumes of one of two mirror versions; the version wanted in a new drug, for example. Existing pharmaceuticals, such as paroxetine, for treatment of anxiety and depression, and the antiviral medicine oseltamivir, for respiratory infections, are more efficiently produced using asymmetric organocatalysis. It is also possible to artificially produce potentially curative substances that can otherwise only be isolated in small amounts from rare plants or deep-sea organisms, described the Royal Swedish Academy for Sciences. Since the Laureate’s discoveries in 2000, the use of asymmetric organocatalysis has rapidly increased. In just two decades, the field had become very dynamic and important, and the advantages are many. As described by List in his Nobel lecture, catalysis itself is one of our key technologies, perhaps our most important one. Around 90% of industrial-scale chemical reactions use catalysis and 35% of our global GDP is based on catalysis. When it comes to asymmetric organocatalysis, besides being a more effective way of producing pharmaceuticals, the method has also given us a green alternative for molecule production, since organic catalysts are more environmentally friendly than their metal counterparts. The catalysts are also a greener option because they can work on a sort of conveyor belt. Before 2000, a lot of chemical substances were lost during the chemical construction process of molecules, because each intermediate product had to be isolated and purified. Organocatalysts are also much easier to work with, and with their help the production process can be carried out in an unbroken sequence. This is called a cascade reaction, which can considerably reduce waste in chemical manufacturing. With less interference in the process, less chemical waste is produced. The Laureates also showed that this is a method that any chemist can do, without fancy equipment. Overall, the title of MacMillan’s Nobel lecture summarizes the importance of the Nobel discovery in Chemistry 2021 very well: “Democratizing catalysis for a sustainable world.” NLS ILLUSTRATION WIKIPEDIA