The ability of fluorine to alter the physical and chemical properties of organic molecules has been used in the design of drugs and new materials. Fluorinated heterocycles, especially carbohydrates, are very interesting to pharmaceutical and agrochemical industries due to their biological activity. Besides, they can also present other kinds of applications such as preparation of liquid crystals. The present known methodologies in the synthesis of fluorosugars afford mixture of several compounds, diminishing the yield of the reaction and making their purification more difficult. In this project, we propose the intramolecular palladium-catalysed cyclisation of allylic fluorides as a methodology for the preparation of fluorinated heterocycles that can be easily transformed in their corresponding carbohydrates.
The use of allyl fluorides in reactions catalyse for palladium complexes has not been well studied. With this in mind, this project will be based on finding the conditions to conduct the intramolecular palladium-catalysed cyclisation of nitrogen- or oxygen-containing allyl fluorides, affording the corresponding fluorinated 5- or 6-membered-rings. To reach these aims, two methodologies will be used, intramolecular Wacker-type reaction and preparation of allyl palladium complex by elimination of a silylated or an acetate groups, followed by intramolecular cyclisation.
The possibility of preparing the allylpalladium complex by elimination of fluorine or by elimination of the other group (silicon or acetate, depending on the reactivity of the starting material to give the fluorinated complex) will afford different ways of preparing fluorinated or nonfluorinated heterocycles. The allyl fluorides will be synthesised using methodologies developed and learnt during the postdoctoral stage. Finally, it is worthy highlighting the use of chiral ligands to obtain enantiopure compounds.
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