Periodic Reporting for period 1 - ThioBioCat (Development of Biocatalytic Strategies for the Synthesis of Chiral Thiols and Thioethers)
Reporting period: 2023-02-01 to 2025-01-31
In chemistry, chiral molecules are mirror images of each other. Synthesis of the right enantiomer is of particular importance, especially for active pharmaceutical ingredients (APIs) where the biological effect of the compound is crucial. This synthesis often involves harsh conditions or toxic metals and is thus unsuitable for medical compounds, as well as harmful for the environment. Funded by the Marie Skłodowska-Curie Actions (MSCA) programme, the ThioBioCat project will exploit the power of enzymes, which accelerate chemical reactions in all living organisms, to develop new tools for the synthesis of important chemicals, such as active pharmaceutical ingredients (APIs). Enzymes have the inherent ability to facilitate chemical synthesis in a simple and environmentally friendly manner and offer an advantage in the production of compounds destined for human use.
We focussed on the biocatalytic synthesis of chiral thiols and thioethers, which are a functional group found in many APIs but with very limited enzymatic strategies for their synthesis. We explored a plethora of potential strategies which led us to find the ability of a certain class of enzyme, ene reductases, to generate α-acyl radicals as a new strategy for the synthesis of thioethers. We carried out mechanistic studies to understand this unique ability of ene reductases to control the highly reactive intermediates formed during the catalysis. This reaction was scaled up and the product isolated (10.26434/chemrxiv-2024-shnqc; 10.1021/jacs.5c00761).
In the ThioBioCat project, we also developed several other new biocatalytic strategies for the synthesis of chiral molecules, not limited to thiols and thioether. We developed a cascade combining three different types of enzymes to create a fragment of the API BMS-986278 which is currently in clinical trials, starting from a cheap and readily available precursor. Combing C-H activation by unspecific peroxygenase to install an allylic ketone, ene reduction by ene reductase, and finally keto reduction by alcohol dehydrogenase, we synthesised the final fragment containing two stereocentres with high purity (10.1021/acscatal.4c00177).
This research was also presented at several international conferences, one of which I helped organise every year since 2022, NextGenBiocat which aims to bring together early career researchers in biocatalysis. I was involved in the training of master and PhD students, and in turn received training in several techniques, most notably stopped-flow spectroscopy which allows us to follow fast processes to better understand enzyme mechanisms.
In the ThioBioCat project, we also developed several other new biocatalytic strategies for the synthesis of chiral molecules, not limited to thiols and thioether. We developed a cascade combining three different types of enzymes to create a fragment of the API BMS-986278 which is currently in clinical trials, starting from a cheap and readily available precursor. Combing C-H activation by unspecific peroxygenase to install an allylic ketone, ene reduction by ene reductase, and finally keto reduction by alcohol dehydrogenase, we synthesised the final fragment containing two stereocentres with high purity (10.1021/acscatal.4c00177).
This research was also presented at several international conferences, one of which I helped organise every year since 2022, NextGenBiocat which aims to bring together early career researchers in biocatalysis. I was involved in the training of master and PhD students, and in turn received training in several techniques, most notably stopped-flow spectroscopy which allows us to follow fast processes to better understand enzyme mechanisms.
During the two years of ThioBioCat, we developed several new enzymatic strategies to obtain chiral compounds with high selectivity, and discovered a new reactivity of ene reductases. We developed a new enzymatic strategy for the synthesis of chiral thioethers with high enantioselectivity, and with access to opposite enantiomers. This reaction currently requires very high enzyme concentrations (about 250x higher than required by industry). Further exploration of the enzyme mechanism and enzyme engineering have to be carried out in order to improve the enzyme and make this a viable strategy on process scale.