The Nobel Prize in Chemistry 1950 was awarded jointly to Otto Paul Hermann Diels and Kurt Alder "for their discovery and development of the diene synthesis".
 

The 1950 Nobel Prize in Chemistry acknowledged one of the most powerful and versatile reactions chemists have in their toolbox. Otto Diels and his then student Karl Alder noticed a peculiar interaction between two compounds – one molecule containing four carbon atoms linked by two double bonds separated by a single bond, known as a diene, and another molecule containing two carbon atoms linked by a double bond. Diels and Alder provided the first description of how this proceeds in practice, and consequently the reaction was named after them. Diels and Alder also showed that their reaction had broad application, enabling the creation of a host of ring structures found regularly in natural compounds.