Synthese von 2-Fluorenonen

Synthesis of 2-fluoroenones Fluorinated molecules are of increasing importance in our lives, especially in pharmaceutics and agra chemicals. In the first part of the thesis, a new method is reported for the synthesis of 2-fluoroenones from enones. The enones react with TMSOTf and a nucleophile (pyridine or DMAP) to an intermediate enolether, which then is fluorinated with selectfluor to the corresponding 2-fluoroketone. The elimination of the nucleophile is performed with NaOH to gain the desired 2-fluoroenones. The 2-fluoroenones thus can be obtained in moderate to good yields. In the second part of this thesis, the asymmetric trifluormethylation of carbonyles and imines was investigated. This should be achieved by using chiral metal-trifluormethyl-complexes, chiral Lewis acids or chiral (thio)urea catalysed reactions. None of these reactions led to the desired enantioenriched product. Only the chiral Lewis acid catalysed reaction lead to racemic product. But the investigation showed, that only the anion of the Lewis acid is needed to promote the trifluormethylation reaction. In the next chapter, the asymmetric total synthesis of mevalonic acid should be accomplished. It was planed to use the well established method of the rhodium/BINAP-catalyzed 1,2-addition of trimethylaluminium to enones followed up by a Tamao-Fleming oxidation. On the first route the Tamao-Fleming oxidation and on the second route the ring closing metathesis couldn't be realized. In the fourth part of this thesis, the rhodium/BINAP-catalyzed 1,2-addition or the copper/phosphoramidite catalyzed asymmetric 1,4-additions of dialkylzinc reagents to iminium ions was investigated. At first, the substrate scope of the Reetz synthesis of iminium ions was expanded. Then, the iminium ion was used as the starting material in the copper/phosphoramidite catalyzed asymmetric 1,4-addition which, after hydrolysis, gave the 1,4-adduct of the corresponding ketone in 20% yield with 40% ee. The addition of Grignard reagents, in the absence of catalyst, also led to the 1,4-adduct in moderate yields. In the last part, a new synthetic route for the synthesis of Iromycin-Piericidin hybrides is reported. In the first step, the pyridon is O,O-protected with MOMCl diprotected in 88% yield and then chlorinated with C2Cl6 in 88% yield. This chloride is coupled in a nickel-catalysed reaction with an alane in 69% yield and then quantitatively deprotected with HCl to yield the Iromycin-Piericidin hybride.