Application Of Cyclopalladated Ferrocenylimines In Transmetallation And Heck Reactions

In this thesis, the progress made in the studies of both the transmetallation reaction and Heck reaction was reviewed in detail, on the basis of which the application of cyclopalladated ferrocenylimines in transmetallation and Heck reactions were studied in the following two aspects.1. The application of cyclopalladated ferrocenylimines in transmetallation reaction.A series of opitically active cyclostannated ferrocenylimines (Sp, Sp)-2 were synthesized by transmetallation of optically active cyclopalladated ferrocenylimines. The absolute configurations of (Sp, Sp)-2 were determined by X-ray diffraction and checked by CD spectra.1. A series of optically active cyclopalladated ferrocenylimine dimers (Sp, Sp)-l were obtained via resolution of cyclopalladated ferrocenylimines by using L-leucine as chiral auxiliary (Scheme 1). The opitically active cyclostannatedferrocenylimines (Sp, Sp)-2 were obtained by the transmetallation of optically active cyclopalladated ferrocenylimine dimers (Sp, Sp)-l with metallic tin (Scheme 2).Ar=p-CH3C6H4(a), p-ClC6H4(b), m-OCH3C6H4(c) m-ClC6H4(d), o-CH3C6H4(e), w-CH3C6H4(f)Scheme 22. The composition and structure of the products (Sp, Sp)-2 were characterized by elemental analysis, IR and 'H NMR spectra. The structure and absolute configuration of (Sp, Sp)-2 were determined by X-ray diffraction and checked by CD spectra. The result shows that the transmetallation proceeded with the retention of the absolute configuration of the ferrocene moieties. The N-Sn distances of 0.2521nm [N(l)Sn(l)J and 0.2497nm [N(2)Sn(l)] were more shorter than the sum of the van der Walls radii of N, Sn (about 0.36nm), indicating a substantial intramolecular coordination between N and Sn.2. The application of cyclopalladated ferrocenylimines in Heck reaction.1. Cyclopalladated ferrocennylimines 1-9 (Scheme 3) were synthesizedand applied to Heck reaction. All of them could catalyze the arylation of ethyl acrylate with iodobenzene, and the yields were not significantly influenced by substituent effect (Scheme 4).2. Low-polarity solvent, 1, 4- dioxane was proved as appropriate as high-polarity solvent such as DMF.3. The coupling reactiortfof iodobenzene, aryl bromides and aryl chlorides with different olefins catalyzed by catalyst 2 were studied. It was found that catalyst 2 was also efficient to catalyze the Heck reaction in the case of aryl bromides and aryl chlorides (Scheme 5).Scheme 54. Optimal results of the coupling of iodobenzene with ethyl, butyl acrylate were obtained with 7.36xl06 turnover number and 92% yield.5. The catalyst 2 used to catalyze the coupling of iodobenzene with ethyl acrylate could be reused at least five times.6. Some of the reactions were followed by HPLC (Fig. 1 and Fig. 2). The mechanism based on Pd(0)/Pd( II) circle was proposed (Fig. 3).Fig. 1 Plot of percentages of yield (? and unconvertedsubstrate(H) vs time for Heck reaction of iodobenzenewith butyl acrylate (reaction 1 of table 6)Fig. 2 Plot of percentage yield vs time for Heck reaction of 1 (? and 2 (? of table 7Fig. 3 Proposed mechanism for Heck reaction catalyzedby cyclopalladated ferrocenylimines.a, preactivation; b, oxidative addition; c, coordination and migratory insertion; d, /^-hydrogen elimination; e, neutralization and reduction.This Palladacycle catalyzed Heck reaction was characterized by a wide variety of substrates, mildness of reaction conditions, freedom from protection of inert gases and high catalytic activity retainable after repeated uses.7. The coupling of iodobenzene with styrene was studied by perpendicularity experiment.8. Cyclopalladated ferrocenylimines 2 was applied to catalyzing Heck reactions in neat water. Some commercial surfactants, including the commonly used quaternary ammonium salts, have been proved good to excellent in promoting the reactions. Similar to Heck reactions conducted in the organic solvents, Et3N and NaO Ac were proved to be the...