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1.
The first highly enantioenriched and enantiopure planar chiral 2-phosphino-1-aminoferrocene ligands and their Ir(COD)BArF complexes are reported. The ligands display bidentate coordination behavior towards iridium, as indicated by trends in 31P and 1H NMR spectra of the phosphine moieties and the α to nitrogen substituents of the amines. All of the new complexes showed good reactivity as catalysts in promoting asymmetric hydrogenation of several prochiral alkenes, with enantioselectivities up to 92%. Iridium complexes of dimethylaminoferrocene derivatives containing P-Ar groups [PPh2 and P(o-tol)2] gave the highest levels of asymmetric induction. 相似文献
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Asymmetric hydrogenation of olefins is one of the most important reactions for the synthesis of optically active compounds, especially in industry. Chiral iridium catalysts based on P,N ligands have strongly expanded their application range. In contrast to rhodium and ruthenium diphosphine complexes they do not require the presence of a coordinating group near the C=C bond and, therefore, allow highly enantioselective hydrogenations of largely unfunctionalized alkenes. 相似文献
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L. O. Nindakova F. K. Shmidt E. I. Klabunovskii V. N. Sheveleva V. A. Pavlov 《Russian Chemical Bulletin》1981,30(11):2177-2178
Conclusions We were the first to effect the enantioselective hydrogenation of a mixture of isomeric 2-phenylbutenes on chiral cobalt catalytic systems of the Ziegler-Natta type in an optical yield of 25%.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2621–2622, November, 1981. 相似文献
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F. K. Shmidt Y. S. Levkovskii V. V. Saraev N. M. Ryutina O. L. Kosinskii T. I. Bakunina 《Reaction Kinetics and Catalysis Letters》1977,7(4):445-450
Coupled hydrogenation of arenes with alkenes and dienes proceeds under mild conditions in the presence of a phosphine-modified cobalt system as well as of H3Co[P(C4H9)3]3. Benzene hydrogenation products are cyclohexene (up to 25%) and cyclohexane. By the ESR method, a Co(0) complex containing P(C4H9)3, an arene molecule and AlR3 as ligands has been identified in the catalytic system Al(C2H5)3+Co(C5H7O2)2+P(C4H9)3. The nature of the active complex and the possible mechanism of the coupled process are discussed.
, , H3Co[P(C4H9)3]3 . ( 25%) . Al(C2H5)3+Co(C5H7O2)2+P(C4H9)3 Co(0), P(C4H9)3, AlR3. .相似文献
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The Cu(I) complex of (1R,3R)-bis(diphenylphosphinoxy)-1,3-diphenylpropane (BDPODP) has been prepared and used for the transfer of the ligand to Rh(I). The Rh(I) complexes of this new phosphinite obtained by this method act as efficient asymmetric homogeneous hydrogenation catalysts for (Z)-α-(acylamino)-cinnamic acids. 相似文献
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Asymmetric transfer hydrogenation of N-substituted (3S)-3-amino-1-chloro-4-phenyl-2-butanones in the presence of CpRhCl[(R,R)-Tsdpen] (S/C = 1000) with a mixture of formic acid/triethylamine gave N-substituted (2R,3S)-3-amino-1-chloro-2-hydroxy-4-phenylbutanes with up to 93% de in a quantitative yield, and reduction with the enantiomeric catalyst CpRhCl[(S,S)-Tsdpen] gave (2S,3S)-diastereomeric alcohol with up to 96% de. 相似文献
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Thomas S. Janik Michael F. Pyszczek Patrick.S. Sullivan Jim D. Atwood 《Journal of organometallic chemistry》1984,272(3):427-433
The potential of several alkylcobalt complexes as catalysts for hydrogenation and isomerization of alkenes has been investigated. The complexes CH3Co(CO)2(Pom-Pom) (Pom-Pom = 1,2 bis(dimethoxyphosphino)ethane), CH3Co(CO)3P(OMe)3 and C6H5CH2Co(CO)3PPh 3 are compared to CH3Co(CO)2(P(OMe)3)2, for their ability to function in catalytic cycles. Each is active for hydrogenation and isomerization of alkenes under conditions where the carbonylation-decarbonylation equilibrium is readily established. The lifetime for the complexes is much shorter than for CH3Co(CO)2 (P(OMe)3)2 suggesting that two phosphorus donors in trans positions in an intermediate is a requirement for catalyst stability in these alkylcobalt complexes. 相似文献
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The catalytic homogeneous hydrogenation of electron‐deficient alkenes (nucleophilic hydrogenation) was achieved in the presence of iridium complexes and a base as co‐catalyst. Contrary to hydrogenation of electron‐rich alkenes, which is inactivated by bases, the hydrogenation of the electron‐deficient alkenes turned out to be base activated. Here, we present a more thorough study on the capacities but also limitations of this new reaction mechanism using screenings of the reaction conditions as well as different Ir complexes and substrates. The formation of a catalytically active Ir complex is proposed. The active complex usually attacks a soft electron‐deficient atom, if more than one possibility exists (as shown by density functional theory computations). Additionally, first examples of enantiomeric enrichments in the presence of chiral Ir complexes are presented. The high catalyst load needed and the moderate yields show that the active complex is very unstable under conditions of nucleophilic hydrogenation and is quickly deactivated, which has to be addressed in further studies. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Colladon M Scarso A Sgarbossa P Michelin RA Strukul G 《Journal of the American Chemical Society》2006,128(43):14006-14007
Easily accessible chiral PtII complexes 1 allow highly enantioselective and completely regioselective asymmetric epoxidation of terminal alkenes with hydrogen peroxide 相似文献
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C. Cativiela J. A. Mayoral E. Melendez R. Usón L. A. Oro M. T. Pinillos 《Reaction Kinetics and Catalysis Letters》1982,21(1-2):173-177
Z-2-benzamido(acetamido)-3-(3-indolyl)-2-propenoic acids were hydrogenated with neutral and cationic rhodium(I) complexes containing the chiral diphosphine (–) or (+)–2,3-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)-butane [(–) or (+)–DIOP].
Z-2- ()-3-(3-)-2- () (I), (–) (+)-2,3--2,3--1,4- ()-.相似文献
13.
Iridium-based asymmetric reduction of ketones to chiral enantiomerically enriched alcohols has recently attracted attention by a number of research groups and interest in this area is growing. This review presents the different catalytic systems based on iridium complexes that have been used in asymmetric hydrosilylation, in asymmetric transfer hydrogenation (ATH) with alcohols or formic acid derivatives as reducing agents, and in asymmetric hydrogenation (H2 as reducing agent). A large variety of chiral ligands of various denticities and bearing various combination of coordinating atoms (N, P, S, O, C, …) have been used and will be presented. The last part critically reviews the mechanistic understanding of all the above transformations with specific reference to iridium catalysts. 相似文献
14.
Asymmetric hydrogenation of N-acetamidoacrylic acid derivatives has been achieved using a rhodium complex in the presence of a series of readily made chiral diphosphinites, small changes in the stereochemistry of which lead to significant difference in the optical yield of reduced product. 相似文献
15.
Hems WP McMorn P Riddel S Watson S Hancock FE Hutchings GJ 《Organic & biomolecular chemistry》2005,3(8):1547-1550
Rh diphosphine complexes using DuPhos and JosiPhos as chiral ligands have been immobilised by ion exchange into the mesoporous material MCM-41. When used as catalysts for the enantioselective hydrogenation of dimethyl itaconate and methyl-2-acetamidoacrylate, these heterogeneous catalysts give catalytic performance in terms of yield and enantioselection that are comparable to the corresponding homogeneous catalysts. Furthermore, the heterogeneous catalysts can be readily recovered and reused without loss of catalyst performance. A second immobilisation strategy is described in which [Rh(COD)2]+BF4- is initially immobilised by ion exchange and subsequently modified by the chiral diphosphine and this give comparable catalyst performance. This immobilisation strategy opens up the possibility of easy ligand-screening for parallel synthesis and libraries. 相似文献
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Several zwitterionic iridium complexes based on chiral P,N-ligands with imidazoline or oxazoline donors and anionic tetraarylborate or aryltrifluoroborate substituents have been synthesized. The corresponding cationic analogues have also been prepared, to evaluate the effect of the covalent linkage between the anion and the cationic metal complex in catalytic reactions. The respective pairs of structurally analogous precatalysts have been compared for their efficacies in the asymmetric hydrogenation of unfunctionalized olefins. In most cases, the anionic derivatization has virtually no influence on the asymmetric induction of the iridium complex. This is in accordance with X-ray structural studies, which have shown that the chiral environment of the cationic metal center is not affected by the anionic substituent. Depending on the nature of the counterion employed, the zwitterionic catalysts proved to be significantly more reactive than their cationic counterparts in nonpolar solvents. 相似文献
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《Journal of organometallic chemistry》1986,302(2):265-267
The complexes formed in situ from Ir(COD)acac and chiral menthylphenylphosphines proved to be active catalysts in the hydrogen transfer reaction from isopropanol to prochiral ketones. When acetophenone was used, optical yields of up to 42% were achieved, the configuration of the carbinols being dependent on the bulkiness of the phosphine employed. Concerning the reaction rate, the activation process and the P/Ir ratio, the two menthyl-substituted phenylphosphines display different behaviour. 相似文献
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《Tetrahedron letters》1998,39(18):2809-2812
By reaction with ammonium persulfate the easily available diselenide derived from (1R)-(+)-camphor was converted into the camphorselenenyl sulfate. This chiral electrophilic selenium reagent reacted at room temperature with alkenes in the presence of methanol to afford selenomethoxylated adducts in good yields and with moderate to good facial selectivity. The two diastereomeric addition products could be separated in most cases. 相似文献