Szelektív átalakulások heterogenizált fémkomplexeken = Selective transformations on heterogenized organometallic complexes

Az elvégzett munka összefoglalóját évenkénti bontásban adjuk meg. 2003: Előállítottuk Ru(OH)3/Al2O3 katalizátort és sikeresen alkalmaztuk az optikailag tiszta 1-feniletanol racemizációjában. Az alkoholok racemizációja során kapott eredményeket szteroid alkoholokra alkalmazva, sikerült egy egyszerű eljárást kidolgozni a más úton nehezen előállítható 17-ösztradiol-3-metiléter előállítására. 2004: Az enantioszelektív hidrogénezések vizsgálata során a Veszprémi Egyetemen előállított [Rh(nbd)(2S,4S)-bdpp]ClO4 komplexet heterogenizáltuk sikerrel. Az immobilizált komplexet és (Z)-acetamidofahéjsav és metil-észtere hidrogénezésében használva igazoltuk, hogy katalizátorunk megőrizte eredeti aktivitását és szelektivitását. 2005: Különbözőképpen szubsztituált [Rh(2S,4S)-bdpp]PF6 komplexeket heterogenizáltuk Al2O3 hordozón . Homogén közegben a ligandumok bázikusságával párhuzamosan nőtt a katalizátorok aktivitása és enantioszelektivitása. A heterogenizált komplexek az oldható komplexekhez hasonló aktivitást és szelektivitást mutattak. 2006: Kiterjesztettük az aszimmetrikus hidrogénezések vizsgálatát a C=O kötés hidrogénezésére. A korábban a C=C kötés hidrogénezésében aktív katalizátorokat az acetofenon és szubsztituált származékainak hirogénezésében alkalmaztuk. Eredményeink a ligandumok bázicitásának függvényében az aktivitás és a szelektivitás növekedését igazolták. | The summary of the work in each year. 2003: We have prepared the Ru(OH)3/Al2O3 catalyst and applied successfully in the racemization of optically pure 1-phenylethanol . The results obtained for the racemization of alcohols were applied in the epimerization of steroid alcohols. 2004: Studying the enantioselective hydrogenations we have heterogenized succesfully [Rh(nbd)(2S,4S)-bdpp]ClO4 complex, which was originally prepared by the University of Veszprém. The prepared catalyst was applied in the hydrogenation of (Z)-acetamidocinnamic acid and its methyl ester. 2005: We have heterogenized several differently substituted [Rh(2S,4S)-bdpp]PF6 complexes on Al2O3 support. In homogeneous condition the activity and selectivity of the complexes were increased with increasing ligand basicity. Using the heterogenized samples we have observed the same trend as in the case of the homogeneous complexes. 2006: The catalyst which were active in the hydrogenation of C=C double bond were applied in the hydrogenation of acetophenone and its substituted derivatives. Our results could prove the increase of activity and selectivity as a function of increasing ligand basicity. We have also could prove the connection between the electronic effects of substituents and the activity of the hydrogenation

Enantioselective α-Hydroxylation of 2-Arylacetic Acid Derivatives and Buspirone Catalyzed by Engineered Cytochrome P450 BM-3

Here we report that an engineered microbial cytochrome P450 BM-3 (CYP102A subfamily) efficiently catalyzes the α-hydroxylation of phenylacetic acid esters. This P450 BM-3 variant also produces the authentic human metabolite of buspirone, R-6-hydroxybuspirone, with 99.5% ee

Confirming the existence of π-allyl-palladium intermediates during the reaction of meta photocycloadducts with palladium(ii) compounds

The transient existence of π-allyl-palladium intermediates formed by the reaction of Pd(OAc)2 and anisole-derived meta photocycloadducts has been demonstrated using NMR techniques. The intermediates tended to be short-lived and underwent rapid reductive elimination of palladium metal to form allylic acetates, however this degradation process could be delayed by changing the reaction solvent from acetonitrile to chloroform

Construction of Tetrahydrofurans by Pd II /Pd IV -Catalyzed Aminooxygenation of Alkenes

No AbstractPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/56153/1/5737_ftp.pd

Construction of Tetrahydrofurans by Pd II /Pd IV -Catalyzed Aminooxygenation of Alkenes

No AbstractPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/56117/1/5839_ftp.pd

The diastereoselective Meth-Cohn epoxidation of camphor-derived vinyl sulfones

Some camphor-derived vinyl sulfones bearing oxygen functionality at the allylic position have been synthesized and their nucleophilic epoxidation reactions under Meth-Cohn conditions have been explored. The γ-oxygenated camphor-derived vinyl sulfones underwent mildly diastereoselective nucleophilic epoxidation reactions, affording the derived sulfonyloxiranes in up to 5.8:1 dr. The observed diastereoselectivities were sensitive to the reaction conditions employed. In contrast, no stereoselectivity was observed in the nucleophilic epoxidation of the corresponding γ-oxygenated isobornyl vinyl sulfone. A tentative mechanism has been proposed to explain the origins of the diastereoselectivit

The kinetics and mechanism of the organo-iridium catalysed racemisation of amines

The dimeric iodo-iridium complex [IrCp*I2 ]2 (Cp*=pentamethylcyclopentadiene) is an efficient catalyst for the racemisation of secondary and tertiary amines at ambient and higher temperatures with a low catalyst loading. The racemisation occurs with pseudo-first-order kinetics and the orresponding four rate constants were obtained by monitoring the time dependence of the concentrations of the (R) and (S) enantiomers starting with either pure (R) or (S) and show a first-order dependence on catalyst concentration. Low temperature 1H NMR data is consistent with the formation of a 1:1 complex with the amine coordinated to the iridium and with both iodide anions still bound to the metal-ion, but at the higher temperatures used for kinetic studies binding is weak and so no saturation zero-order kinetics are observed. A cross-over experiment with isotopically labelled amines demonstrates the intermediate formation of an imine which can dissociate from the iridium complex. Replacing the iodides in the catalyst by other ligands or having an amide substituent in Cp* results in a much less effective catalysts for the racemisation of amines. The rate constants for a deuterated amine yield a significant primary kinetic isotope effect kH/kD = 3.24 ndicating that hydride transfer is involved in the rate-limiting step