Irina Geibel and Anna Dierks have discovered a new chemical reaction – an absolute rarity these days. With their discovery, the two chemists could help to develop new medicines.
A doctoral candidate, an undergraduate 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 of producing lactones. These chemical compounds, which also occur naturally, are important, for example, for the development of new medicines. The chemists recently published their findings in *The Journal of Organic Chemistry* – an internationally renowned specialist journal.
Doctoral candidate Irina Geibel made the discovery rather by chance whilst conducting research at the Institute of Chemistry into a cerium catalyst for linking individual chemical building blocks to form valuable products. In the process, she observed a side reaction that produced the lactone. “The moment we realised that it really was a new reaction was special – all our hard work had paid off,” says the doctoral candidate. Student Dierks adds: “I never would have expected to be able to work on something like this whilst I was still an undergraduate.” What is distinctive about lactone production using this method is that “it does not generate large quantities of undesirable waste, as is the case with other methods,” explains Geibel.
It was Dierks who, following Geibel’s discovery, optimised the reaction for her Bachelor’s thesis in such a way that the lactone emerged as the main product. Dr Marc Schmidtmann, a crystallographer from Oldenburg, helped her to determine the structure of the products produced. Lactones are an important class of chemical compounds that occur naturally in foodstuffs; for example, they give various types of fruit their flavour.
What is remarkable about the newly discovered reaction is that, in addition to linking two carbon atoms, an oxygen atom from the air is incorporated, resulting in a lactone as the product. The new reaction could play a major role in the development of new, more effective medicines, which is why the chemists now want to analyse it in detail and find out exactly how it works. “However, it may take several more years before we have fully elucidated the reaction,” says Geibel.
Anna Dierks explains how the discovery was made using a clear example: “You can think of it as being like cooking. We take various ingredients, mix them together at a certain temperature and see what comes out. It is important, however, that the catalyst is right, because without it, no reaction takes place.”
The catalyst is a metal compound newly developed by the Oldenburg scientists, which makes the reaction possible in the first place. For Geibel and Dierks’ supervisor, Prof. Dr Jens Christoffers, a lecturer in chemistry at the university, the discovery is also something special. “It is a very rare occurrence for new chemical reactions to be discovered these days. It is thanks to the keen observational skills of the two researchers that this has been achieved as part of a PhD thesis,” said Christoffers.
Publishing their findings was a major – and not entirely straightforward – step for the two chemists. Initially, with the help of their supervisor Christoffers, the pair drafted a manuscript which they submitted to a specialist journal. However, the reviewers requested details of the reaction mechanism, which is as yet unknown. Consequently, the publication was rejected. “But that’s not all that 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 early-career researchers have further insights into their new reaction, they intend to publish these as well.
“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
