Irina Geibel and Anna Dierks have discovered a new chemical reaction - an absolute rarity these days. With their discovery, the two chemists could contribute to the development of new medicines.
A PhD student, a student and chemical compounds - in the case of Irina Geibel and Anna Dierks, these are the ingredients for a recipe for success. Together, the two young scientists from Oldenburg have succeeded in discovering a new way to produce lactones. These naturally occurring chemical compounds are important for the development of new medicines, for example. The chemists recently published their findings in "The Journal of Organic Chemistry" - an internationally renowned scientific journal.
Doctoral student Irina Geibel made the discovery by chance while researching a cerium catalyst for linking individual chemical building blocks to form valuable products at the Institute of Chemistry. In the process, she observed a side reaction that produced the lactone. "The moment when we realised that it really was a new reaction was special - our hard work paid off," says the doctoral student. Student Dierks adds: "I never expected to be able to work on something like this during my studies." What characterises the production of lactone using this process is that "there are no large quantities of unpleasant waste, as is the case with other processes," explains Geibel.
Dierks was the one who optimised the reaction for her bachelor's thesis after Geibel's discovery so that the lactone emerged as the main product. Oldenburg crystallographer Dr Marc Schmidtmann supported her in determining the structure of the products produced. Lactones are an important class of chemical compounds that occur naturally in food and give various types of fruit their flavour, for example.
The remarkable thing about the newly discovered reaction is that in addition to the linking of two carbon atoms, an oxygen atom from the air is incorporated, resulting in a lactone as a product. The new reaction could play a major role in the development of new, more effective drugs, which is why the chemists now want to analyse and find out exactly how it works in detail. "However, it may take a few more years before we have fully elucidated the reaction," says Geibel.
Anna Dierks explains how the discovery was made with the help of a vivid example: "You can imagine it like cooking. We take different ingredients, stir them together at a certain temperature and see what comes out. However, it is important that the catalyser is right, because without it, no reaction takes place."
The catalyst is a new metal compound developed by the Oldenburg scientists that makes the reaction possible in the first place. The discovery is also something special for Geibel and Dierk's supervisor, Prof Dr Jens Christoffers, Professor of Chemistry at the university. "It is a very rare event that new chemical reactions are still being discovered these days. It is thanks to the great powers of observation of the two employees that this has been achieved as part of a doctoral thesis," says Christoffers.
Publishing their findings was a major - and not entirely uncomplicated - step for the two chemists. Firstly, with the help of their supervisor Christoffers, they wrote a manuscript which they sent to a specialist journal. However, the reviewers requested the reaction mechanism, which is still unknown. As a result, the publication was rejected. "But that's not so unusual," says Geibel. "We then revised the manuscript and sent it to the even more prestigious Journal of Organic Chemistry - and were successful." As soon as the two young scientists have further insights into their new reaction, they want to publish it again.
"Formation of δ-Lactones by Cerium-Catalyzed, Baeyer-Villiger-Type Coupling of β-Oxoesters, Enol Acetates and Dioxygen", Irina Geibel, Anna Dierks, Marc Schmidtmann and Jens Christoffers, J. Org. Chem. 2016, 81, 7790-7798. DOI: 10.1021/acs.joc.6b01441
