Ferrocenyl imidazoline palladium Synthesis and catalytic reaction .
|Keywords||Ferrocenyl imidazoline palladium compounds . Aza - Claisen rearrangement reaction Suzuki coupling reaction Aryl bromides Arylboronic acid|
In this thesis, the properties and synthesis of ferrocenylimidazolines and their cyclopalladated complexes, the palladacycle-catalyzed Aza-Claisen rearrangement reaction, Suzuki reaction have been studied as follows:1) Synthesis and characterization of novel ferrocenylimidazolinesA series of novel ferrocenylimidazolines （5） were synthesized by the condensation of ferrocenylimidic acid methyl ester hydrochloride （3） with corresponding diamines （4） （Scheme 1）. The products were characterized by elemental analysis, IR and NMR spectra. The synthetic methods of ferrocenylimidazolines with different substituents in the imidazoline ring have been developed.2) Synthesis and characterization of cyclopalladated ferrocenylimidazolinesThe reaction of the compounds 5 with Li2PdCl4 in the presence of sodium acetate gave seven novel chloride-bridged palladacycle dimers 6, which was treated with 2 equivalent of triphenylphosphine （PPh3） in methanol at room temperature to produce the corresponding triphenylphosphine （PPh3） adduct 7 （Scheme 2）. These new cyclopalladated complexes were characterized by elemental analysis, IR, NMR spectra. The compounds 7a, 7d and 7g were further confirmed by single crystal X-ray diffraction.3) The appfication of ferrocenylimidazoline palladacycles in Aza-Clasien rearrangement reactionsChloride-bridged palladacycle dimers 6 have been evaluated as highly efficient catalysts for the aza-Claisen rearrangement reaction of allylic imidates without activation with silver and thallium salts. The correlation between the substituents on the imidazoline ring and catalytic activity of palladacycles was established. Additionally, the effect of nature of substrates should also be taken into account. 4) The application of new ferrocenylimidazoline palladacycles 6 in Suzuki cross coupling reactionsChloride-bridged palladacycle dimers 6, which are thermally stable and insensitive to air and moisture, have been evaluated as effective phosphine-free catalysts for the Suzuki reaction of aryl bromides with arylboronic acid. The catalyst 6b presents the highest efficiency in the coupling processes for less reactive 2-bromothiophene. K3PO4·7H2O was found to be the best base and a small amount of water was essential for this catalytic system.5) The application of ferrocenylimidazoline palladacycle 6b in catalyzed Suzuki cross coupling reaction at room temperatureThe novel ferrocenylimidazoline palladacycle 6b was successfully used in Suzuki cross coupling reaction of aryl bromide with with arylboronic acid at room temperature. The coupled products were obtained in excellent yields for the less active aryl bromides with bromides with arylboronic acids with 0.5mol% loading of 6b in the presence of 2 equivalent of K2CO3 as base and 1 equivalent TBAB as additive at room temperature. Ar-Br+Ar’B（OH）2（?）Ar’-Ar