Novel organofluorine motifs in the service of industry

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This project aims to develop two recent discoveries from the St Andrews laboratory. Project 1: The first project develops from a recent syntheses of 1,2,3,4- and 1,2,4,5-tetrafluorocyclohexanes. Importantly the stereochemistry of the molecules has all of the fluorines on the same face of the cyclohexanes. We find that this makes these cyclohexanes very polar. TWhen cyclohexane adopts a chair conformation, then there are always two diaxial C-F bonds. This polarity renders these compounds crystalline solids, and NMR experiments reveal that the two faces are highly polarised. So the project aims now to incorporate this motif into more meaningful structures. We think that the all-syn tetrafluorocyclohexane motif can have wide ranging roles in developing performance molecules for pharmaceuticals and agrochemicals research. However in this project we will use liquid crystals as a background to explore their properties. Many liquid crystalline molecules that are used in modern displays for personal computers, smart phones and iPads etc contain fluorine atoms. This is because the C-F bond is polar, but it has low viscosity, and thus it can orientate and cycle very rapidly in changing electric fields. The all-syn tetraflurocyclohexane motifs appear to have exactly the correct caharacteristics for a particular class of LC's known as -ve dieletric anisotropic LC's. These are molecules where the dipole is orientated perpendicular to the molecular axis. The project requires that we develop chemistry around a phenyl derivative of the 1,2,4,5-tetrafluorocyclohexane. We plan to carry out a diversity of chemistry on this motif, and also to improve synthetic protocols. We want also to explore synthesis routes to other derivatives of the tetrafluorocyclohexane ring system eg. carboxylic acid and amine motifs we feel will be extremely attractive for medicinal chemistry research. One of the leading research companies and global suppliers of perfomance LC's, Merck in Darmstadt, Germany, have agreed to support the project by evaluating candidate compounds as LC's and they will assist in providing facilities to scale up the synthesis of these motifs. This aspect of the project will be successful if we can demonstrate a practical application of the all-syn tetrafluorocyclohexane and illustrate to the wider community its potential in the development of performance organic molecules. Project 2. The second project was stimulated by a new reaction carried out in the laboratory, which recognised that if an acetylenethioether is treated with an HF source, it generates a fluoroviny thioether (RS(F)=CH2). More significantly we find that the fluorovinyl thioether is a relatively stable entity. There is hardly any literature on this motif and in this research we want to explore its potential in the early stage design of enzyme inhibitors (fragment approach). We have recognised that the motif approximates the steric and electronic profile of an enol of a thioester. Thioester enols/ates are important intermediates in enzymology, eg. enzymes that process acetyl-CoA such citrate and malate synthase, acetyl-CoA carboxylase, and enoyl reductases of fatty acid biosynthesis are attractive. Therefore we want to assess if the fluorovinyl thioether moiety will be recognised and bind to these enzyme active sites by co-crystallisation X-ray studies. This requires that we synthesise appropriate motifs that represent truncated pantetheinyl moieties carrying the RS(F)=CH2 motif. These compounds will be co-crystallised with enzymes over-expressed in E. coli. In discussions with Syngenta they have suggested we explore such ligands for enoyl reductase, a target relevant to the agrochemical sector. A successful outcome will show that this motif binds to these enzyme active sites (by X-ray crystallography), and provides a starting poing for fragment based inhibitor development. The programme will introduce this motif to the wider research community.