Pentafluorethyllithium: Untersuchung von Eigenschaften und Reaktivität

Abstract

Perfluoroalkylated compounds have become of great importance in life sciences and technical development as effective and selective pharmaceuticals and pesticides or liquid crystals in active matrix displays. An in this context important novel and green pentafluoroethylating reaction, that lacks the use of environmentally harmful chlorinated or iodinated alkanes was investigated in this dissertation.The stability of pentafluoroethyl lithium (PFELi), which is formed as reactive moiety in this reaction, was investigated by low temperature 19F- and 13C-NMR-spectroscopy. Reactions with various carbonyls have been carried out. Ketones can be transformed into pentafluorinated alcohols. 1,4-cyclohexanedione reacts to the trans product exclusively. The regioselectivity of the reaction of PFELi with 1,4-unsaturated carbonyls can be shifted by usage of bulky aluminium Lewis-acids. Epoxides can be opened with PFELi via activation with TiCl4. Pentafluoroethylated ketones can be synthesised by reaction of PFELi with the corresponding esters in presence of LiBr at -110°C. Some of these ketones can be transformed to pentafluorinated cinnamon acids under conditions of Perkin-reaction. In the BF3 mediated reaction of PFELi and imines a novel pentafluoroethylated borane could be isolated and investigated by X-ray analysis. Chloro phosphines and phosphites could also pentafluoroethylated in a substitution reaction.Pentafluoroethylated carbamoyl phosphonates, potentiell matrix metallo protease inhibitors (MMPI) could synthesised in a convenient one pot reaction.