The 2021 Nobel Prize in Chemistry was awarded jointly to Benjamin List and David MacMillan “for the development of asymmetric organocatalysis”.
To read about the science behind the prize in more detail, check out the Nobel Prize press release here, or the more detailed scientific background here (note that I feel obliged to point out that the latter link includes an example of limonene as a ‘mirror image molecule’ and repeats the false claim that one mirror image is responsible for the smell of oranges while the other is responsible for the smell of lemons. As lovely a story as this would be, it’s simply not true, and it’s a bit bizarre to see the Nobel Prize perpetuating this myth!)