Better ways to fluorinate
There is at least one fluorine atom in 30-40 % of agrochemicals and in 20 % of pharmaceuticals. They provide solubility, bioavailability and metabolic stability, as well as being useful for radioactive labelling and imaging. Despite this, there is no easy method to add fluorine atoms in a specific orientation to organic molecules during industrial synthesis. The EU-funded project 'A transition metal approach to benzylic fluorination' (BENFLU) has addressed the problem by testing a number of new ways to achieve this specificity. Researchers began by testing different sources of fluorine for the reaction. This process yielded Selectfluor, a commercially available fluorine donor, as the best source of fluorine. The next part of BENFLU looked at different sources for hydride, the class of organic chemical needed for this type of reaction. Triethylsilane proved to be the most promising source of the hydride structure required. Further testing and optimisation provided BENFLU researchers with the reaction conditions that gave the best overall yields of specific fluorinated compounds. These were validated using palladium catalysts on a different class of compounds, and proved generally effective. BENFLU work will pave the way to more effective fluorination during industrial chemical synthesis. This will have a far-reaching impact on manufacturing and pharmaceutical industries.
Keywords
Fluorine, industrial synthesis, benzylic fluorination, Selectfluor, triethylsilane
