Palladium-katalysierte enantioselektive Synthese allylischer Thiocarboxylate und Palladium-katalysierte Deracemisierung allylischer Carbonate

The topic of this thesis is the palladium-catalyzed allylic alkylation of potassium thioacetate (KSAc) und potassium thiobenzoate (KSBz) with racemic cyclic and acyclic allylic esters having a symmetrically substituted carbon skeleton by using the Trost ligand. By this method the corresponding allylic thioesters could be achieved with high ee values and yields. The reaction of the acyclic allylic carbonates with KSAc and KSBz afforded the E- and the Z-Isomers of the thioesters. Using cyclic allylic carbonates as substrates the formation of the corresponding allylic alcohols as byproduct was observed. By using allylic acetates as substrates a highly selective kinetic resolution was determined. The palladium-catalyzed reaction of the racemic cyclopentenyl acetate with KSAc showed a strong memory effect. This effect was further probed by studies of the palladium-catalyzed reaction of both the matched acetate of > 99% ee and the mismatched acetate of > 99% ee with KSAc. The second part of this thesis describes the palladium-catalyzed deracemization of allylic carbonates. The palladium-catalyzed reaction of allylic carbonates in the presence of the Trost ligand in H2O / CH2Cl2 furnished the allylic alcohols with high yields and ee values of up to > 99%. It seems to be that the in situ formed HCO3- attacks the palladium allyl complex in order to furnish the allylic alcohol. This assumed mechanism was proved by several experiments