- Efficient Palladium(0) supported on reduced graphene oxide for selective oxidation of olefins using graphene oxide as a ‘solid weak acid’
-
Selective oxidation of olefin derivatives to ketones has made innovative development over palladium(0) supported on reduced graphene oxide. Compared to traditional Wacker oxidation, the novel method offers an economical and environment-friendly option by using graphene oxide (GO) as a ‘solid weak acid’ instead of classical homogeneous catalysts like H2SO4 and CF3COOH. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope and transmission electron microscopy images of Pd0/RGO showed that the nanoscaled Pd particles generated at the flake structure of reduced graphene oxide. Under optimized condition, up to 44 kinds of ketones with different structures can be prepared with excellent yields.
- Gao, Xi,Zhou, Jianhao,Peng, Xinhua
-
-
- Imido-P(v) trianion supported enantiopure neutral tetrahedral Pd(II) cages
-
Charge-neutral chiral hosts are attractive due to their ability to recognize a wide range of guest functionalities and support enantioselective processes. However, reports on such charge-neutral cages are very scarce in the literature. Here, we report an enantiomeric pair of tetrahedral Pd(ii) cages built from chiral tris(imido)phosphate trianions and oxalate linkers, which exhibit enantioselective separation capabilities for epichlorohydrin, β-butyrolactone, and 3-methyl- and 3-ethyl cyclopentanone.
- Rajasekar, Prabhakaran,Pandey, Swechchha,Paithankar, Harshad,Chugh, Jeetender,Steiner, Alexander,Boomishankar, Ramamoorthy
-
supporting information
p. 1873 - 1876
(2018/02/23)
-
- The Cu-catalyzed asymmetric conjugate addition with chiral diphosphite ligands derived from D-(-)-tartaric acid
-
A series of diphosphite ligands, which were derived from D-(-)-tartaric acid, have been synthesized and successfully applied in the Cu-catalyzed asymmetric conjugate addition of organozincs to enones. There was a synergic effect between the stereogenic ce
- Pang, Zeng-Bo,Tian, Mi,Li, Hai-Feng,Wang, Lai-Lai
-
supporting information
p. 618 - 627
(2017/03/15)
-
- Novel MOP-type H8-binaphthyl monodentate phosphite ligands and their applications in transition metal-catalyzed asymmetric 1,4-conjugate additions and hydroformylations
-
A new series of monodentate phosphites based on the rigid, axially chiral monoesterified H8-BINOL, which are easy to prepare from the readily accessible phosphorylating reagents (Sa)- or (Ra)-1,1′-binaphthyl-2,2′-diylchlorophosphite and (Sa)- or (Ra)-1,1′-H8-binaphthyl-2,2′-diylchlorophosphite, have been synthesized. All ligands were purified on a silica gel column under a nitrogen atmosphere with moderate yields, and were white solids and air-stable at room temperature. These ligands afforded good to excellent enantioselectivities in the Cu-catalyzed 1,4-conjugate addition of 2-cyclohexenone with nucleophiles Et2Zn (96% ee) and with Ph2Zn (65% ee), 2-cyclopentenone with Et2Zn (95% ee), 2-cycloheptenone with Et2Zn (76% ee), and 5,6-dihydro-2H-pyran-2-one with Et2Zn (90% ee). In the Rh-catalyzed asymmetric hydroformylation of styrene, these ligands showed a chemoselectivity of >99% in aldehydes, and a satisfactory branched over linear ratio (96/4). Moreover, the sense of the enantiodiscrimination of the products was mainly determined by the configuration of the BINOL-based or H8-BINOL-based phosphocycle.
- Tian, Mi,Pang, Zeng-bo,Li, Hai-feng,Wang, Lai-lai
-
supporting information
p. 330 - 337
(2017/02/18)
-
- Inversions in asymmetric conjugate addition reaction of cyclic enones catalyzed by the Cu/NHC-AgX system: Factors affecting the stereoselective formation of both enantiomers
-
A switchable enantioselectivity was achieved in a Cu-catalyzed asymmetric conjugate addition (ACA) reaction. The ethylene-bridged, hydroxyamide-functionalized NHC-AgI complex, readily accessible from a chiral β-amino alcohol, was found to be a versatile c
- Nakano, Yuki,Sakaguchi, Satoshi
-
p. 407 - 416
(2017/07/28)
-
- Synthesis of epimer of Taniaphos ligand
-
The spatial arrangement of groups within a chiral ligand is essential for its catalytic performance. This work describes convenient synthesis of (R,Sp)-1-(2-(diphenylphosphano)ferrocenyl)-1-(2-diphenylphosphanophenyl)-N,N-dimethylmethanamine, a
- Almássy, Ambroz,Rakovsky, Erik,Malastová, Andrea,Sorádová, Zuzana,?ebesta, Radovan
-
supporting information
p. 130 - 138
(2016/02/05)
-
- Enantioselectivity switch in copper-catalyzed conjugate addition reactions under the influence of a chiral N-heterocyclic carbene-silver complex
-
The asymmetric 1,4-addition of Et2Zn to 2-cyclohexen-1-one using a Cu(i) salt/N-heterocyclic carbene (NHC)-Ag complex catalytic system afforded optically active 3-ethylcyclohexanone. The reversal of enantioselectivity using the same catalytic s
- Matsumoto, Keitaro,Nakano, Yuki,Shibata, Naoatsu,Sakaguchi, Satoshi
-
p. 7755 - 7759
(2016/02/05)
-
- Tartaric acid derivative of the chiral phosphorous ester ligand and its preparation and use
-
The invention relates to two tartaric acid-derived chiral phosphite ligands as well as a synthetic method and application thereof in asymmetric 1,4-conjugated addition reaction of diethylzinc cyclic ketene. The chiral ligands are white solids, and can sta
- -
-
Paragraph 0034; 0059; 0060
(2017/02/09)
-
- Synthesis of novel cyclohexanediol-derived chiral phosphite ligands and their application in the Cu-catalyzed conjugate addition of organozinc to cyclic enones
-
A series of novel chiral diphosphite ligands have been synthesized from (1R,2R)-trans-1,2-cyclohexanediol, (1S,2S)-trans-1,2-cyclohexanediol, racemic trans-1,2-cyclohexanediol and chlorophosphoric acid diary ester, and were successfully employed in the Cu
- Pang, Zeng-Bo,Li, Hai-Feng,Wang, Lai-Lai
-
supporting information
p. 271 - 276
(2018/03/22)
-
- Towards quantitative and scalable transformation of furfural to cyclopentanone with supported gold catalysts
-
Given the vital importance of furfural (FFA) upgrading towards a sustainable bio-based economy, an eco-friendly aqueous route to produce a sole valuable product from FFA is highly desirable. We herein describe an efficient approach to quantitatively convert FFA into cyclopentanone (CPO) in neat water, employing H2 as the clean reductant and supported gold nanoparticles as a simple yet versatile catalyst. The use of anatase TiO2 featuring only mild Lewis acidic sites as the underlying support is essential, not only for preventing undesirable side reactions, but also for attaining high CPO selectivity. The feasibility of using biogenic CPO and CO2 as benign carbon sources to synthesize the industrially important feedstock dimethyl adipate is also demonstrated.
- Zhang, Gao-Shuo,Zhu, Ming-Ming,Zhang, Qi,Liu, Yong-Mei,He, He-Yong,Cao, Yong
-
p. 2155 - 2164
(2016/04/19)
-
- Selective nickel-catalyzed conversion of model and lignin-derived phenolic compounds to cyclohexanone-based polymer building blocks
-
Valorization of lignin is essential for the economics of future lignocellulosic biorefineries. Lignin is converted into novel polymer building blocks through four steps: catalytic hydroprocessing of softwood to form 4-alkylguaiacols, their conversion into 4-alkylcyclohexanols, followed by dehydrogenation to form cyclohexanones, and Baeyer-Villiger oxidation to give caprolactones. The formation of alkylated cyclohexanols is one of the most difficult steps in the series. A liquid-phase process in the presence of nickel on CeO2 or ZrO2 catalysts is demonstrated herein to give the highest cyclohexanol yields. The catalytic reaction with 4-alkylguaiacols follows two parallel pathways with comparable rates: 1) ring hydrogenation with the formation of the corresponding alkylated 2-methoxycyclohexanol, and 2) demethoxylation to form 4-alkylphenol. Although subsequent phenol to cyclohexanol conversion is fast, the rate is limited for the removal of the methoxy group from 2-methoxycyclohexanol. Overall, this last reaction is the rate-limiting step and requires a sufficient temperature (>250°C) to overcome the energy barrier. Substrate reactivity (with respect to the type of alkyl chain) and details of the catalyst properties (nickel loading and nickel particle size) on the reaction rates are reported in detail for the Ni/CeO2 catalyst. The best Ni/CeO2 catalyst reaches 4-alkylcyclohexanol yields over 80 %, is even able to convert real softwood-derived guaiacol mixtures and can be reused in subsequent experiments. A proof of principle of the projected cascade conversion of lignocellulose feedstock entirely into caprolactone is demonstrated by using Cu/ZrO2 for the dehydrogenation step to produce the resultant cyclohexanones (≈80 %) and tin-containing beta zeolite to form 4-alkyl-ε-caprolactones in high yields, according to a Baeyer-Villiger-type oxidation with H2O2.
- Schutyser, Wouter,Van Den Bosch, Sander,Dijkmans, Jan,Turner, Stuart,Meledina, Maria,Van Tendeloo, Gustaaf,Debecker, Damien P.,Sels, Bert F.
-
p. 1805 - 1818
(2015/06/02)
-
- Cu-catalyzed asymmetric conjugate addition of dialkylzincs to enones using a (±)- trans -1,2-cyclohexanediamine-based bis(NHC) derived from l -leucinol
-
A hydroxyamide-functionalized azolium salt as the precursor of a (±)-trans-1,2-cyclohexanediamine-based bis(NHC) ligand was designed and synthesized from readily accessible l-leucinol. The combination of a Cu salt with this chiral ligand precursor promote
- Kamihigashi, Shun,Shibata, Naoatsu,Sakaguchi, Satoshi
-
supporting information
p. 2933 - 2937
(2015/02/02)
-
- Chiral phosphite ligands derived from l-(+)-tartaric acid: Synthesis and application in the Cu-catalyzed 1,4-conjugate addition of organozincs to cyclic enones
-
A new series of chiral phosphite ligands derived from readily available l-(+)-tartaric acid and binaphthol derivatives were designed and prepared in convenient synthetic routes. These ligands were successfully employed in the Cu-catalyzed asymmetric conju
- Xing, Ai-Ping,Bai, Cui-Bing,Wang, Lai-Lai
-
supporting information
p. 455 - 459
(2013/02/23)
-
- Ferrocene phosphane-carbene ligands in Cu-catalyzed enantioselective 1,4-additions of Grignard reagents to α,β-unsaturated carbonyl compounds
-
Chiral ferrocene phosphane-carbenes are good ligands for the copper-catalyzed 1,4-addition of Grignard reagents to various Michael acceptors. The products were obtained in high enantiomeric purity (up to e.r. = 95:5) and excellent regioselectivity (r.r. =
- Csizmadiová, Jana,Me?iarová, Mária,Almássy, Ambroz,Horváth, Branislav,?ebesta, Radovan
-
-
- Tropanes as scaffolds for phosphorus-olefin ligands and their application in asymmetric catalysis
-
Tropane-derived phosphorus-olefin hybrid ligands bearing various combinations of P-units (chiral BINOL-derived units/achiral PPh 2-units) with a tropene skeleton (chiral/achiral) have been synthesized and used in Cu-catalysed conjugate 1,4-addi
- Vlahovic, Sandra,Schaedel, Nicole,Tussetschlaeger, Stefan,Laschat, Sabine
-
supporting information
p. 1580 - 1590
(2013/04/23)
-
- Enantioselective copper-catalyzed 1,4-addition of dialkylzincs to enones using a novel N,N,P-Cu(II) complex
-
Enantioselective copper-catalyzed 1,4-additions of dialkylzincs to enones were carried out in the presence of 1 mol % of Cu(OTf)2 and 2.5 mol % of an N,N,P-ligand possessing a tert-butyl group at the adjacent position of the nitrogen of pyridin
- Ebisu, Yasuhiro,Kawamura, Kenjiro,Hayashi, Masahiko
-
experimental part
p. 959 - 964
(2012/09/25)
-
- Hydroxy-amide functionalized azolium salts for Cu-catalyzed asymmetric conjugate addition: Stereocontrol based on ligand structure and copper precatalyst
-
A series of hydroxy-amide functionalized azolium salts have been designed and synthesized for Cu-catalyzed asymmetric conjugate addition reaction. The (CH2)2-bridged hydroxy-amide functionalized azolium ligand precursors 2, in addition to the previously reported CH2-bridged azolium salts 1, have been prepared from readily available enantiopure β-amino alcohols. The combination of a Cu species with 1 or 2 efficiently promoted the 1,4-addition reaction of cyclic enones with dialkylzincs. For example, the reaction of 2-cyclohepten-1-one (17) with Bu2Zn in the presence of catalytic amounts of Cu(OTf)2 and 1 gave (S)-3-butylcycloheptanone (20) in 99% yield and 96% ee. On the other hand, when the reaction was carried out under the influence of Cu(OTf)2 combined with 2, (R)-20 in preference to (S)-20 was obtained in 98% yield and 80% ee. In this manner, the enantioselecvity was switched by controlling the structure of chiral ligand. Additionally, the reversal of enantioselectivity was also achieved by changing the Cu precatalyst from Cu(OTf)2 to Cu(acac)2 with the same ligand. The combination of Cu(acac) 2 with CH2-bridged azolium salt 1 in the reaction of 17 with Bu2Zn led to formation of (R)-20 as a major product in 55% yield and 80% ee. This result was in contrast to the Cu(OTf)2/1 catalytic system, where the 1,4-adduct with opposite configuration was obtained. Moreover, use of the Cu(acac)2/2 catalytic system produced (S)-20, while (R)-20 was formed by the Cu(OTf)2/2 catalytic system. Thus, it was found that either varying the linker of the chiral ligands or changing the counterion of Cu species between a OTf and acac ligand initially on the metal led to dual enantioselective control in the 1,4-addition reaction.
- Shibata, Naoatsu,Yoshimura, Misato,Yamada, Haruka,Arakawa, Ryuichi,Sakaguchi, Satoshi
-
experimental part
p. 4079 - 4086
(2012/06/04)
-
- Chiral phosphine-phosphite ligands in the enantioselective 1,4-addition of Grignard reagents to α,β-unsaturated carbonyl compounds
-
A library of chiral phosphine-phosphite ligands was evaluated in the Cu-catalyzed asymmetric 1,4-addition of Grignard reagents to cyclopentenone, cycloheptenone and 5,6-dihydro-2H-pyran-2-one. TADDOL-based ligands 1a and 1b with a bulky substituent at the
- Naeemi, Qaseem,Robert, Tobias,Kranz, Darius P.,Velder, Janna,Schmalz, Hans-Guenther
-
scheme or table
p. 887 - 892
(2011/08/22)
-
- Enantioselective copper-catalyzed 1,4-addition of dialkylzincs to enones followed by trapping with allyl iodide derivatives
-
Enantioselective copper-catalyzed 1,4-addition of dialkylzincs to enones proceeded in the presence of 0.1 mol% of Cu(OTf)2 and 0.25 mol% of an N,N,P-ligand containing a quinoline moiety to afford the corresponding conjugated adducts in 99%ee. The intermediate zinc enolates were trapped with substituted allyl iodides to give disubstituted ketones with high diastereoselectivity and enantioselectivity.
- Kawamura, Kenjiro,Fukuzawa, Hitomi,Hayashi, Masahiko
-
experimental part
p. 640 - 647
(2011/08/06)
-
- New chiral monophosphite ligands containing BINOL and/or H 8-BINOL bearing adamantyl substituents: Effect of ligand scaffold on the enantioselective 1,4-conjugate addition of diethylzinc to cyclic enones
-
A series of new bulky monophosphite ligands were synthesized from axially chiral BINOL/H8-BINOL (BINOL: 1-(2-hydroxynaphthalen-1-yl)naphthalen- 2-ol) and highly sterically hindered adamantylcarbonyl chloride. The effectiveness of these ligands
- Wan, Bo,Kwong Fuk, Yee,Wang, Lailai,Xu, Lijin,Zhao, Qinglu,Xing, Aiping
-
experimental part
p. 80 - 85
(2011/10/05)
-
- Asymmetric conjugate addition to cyclic enone catalyzed by Cu-NHC complexes with C2 symmetry
-
A series of chiral, C2 symmetric tridentate N-heterocyclic carbene precursors, containing two N-functionalized hydroxyl or alkoxyl groups, were synthesized. They were applied to catalyze the asymmetric conjugate addition of diethylzinc to cyclo
- Shan, Fengjun,Jiang, Lan,Li, Zhengning,Zhao, Defeng
-
scheme or table
p. 973 - 977
(2012/01/05)
-
- Synthesis of novel chiral bidentatephosphite ligands derived from the pyranoside backbone of monosaccharides and their application in the Cu-catalyzed conjugate addition of dialkylzinc to enones
-
A series of novel bidentatephosphite ligands, derived from methyl 3,6-anhydro-α-d-glucopyranoside and chlorophosphoric acid diaryl ester, were easily synthesized. These ligands were successfully employed in the Cu-catalyzed asymmetric conjugate 1,4-additi
- Zhao, Qing-Lu,Wang, Lai-Lai
-
experimental part
p. 1885 - 1890
(2012/02/05)
-
- Syntheses of simple TADDOL-like phosphite, phosphonite and phosphonate chiral ligands
-
New simple phosphite, phosphonite and phosphonate chiral ligands derived from DIMPTH(OH)2 and rigid bis-DIMPTH(OH)2 were prepared with moderate to good yields (35-86%) from readily available starting materials. The syntheses of the new chiral ligands requ
- Perotti, Jesica P.,Cravero, Raquel M.,Luna, Liliana E.,Grau, Ricardo J. A.,Vaillard, Santiago E.
-
experimental part
p. 92 - 104
(2012/02/01)
-
- Thieme chemistry journal awardees - Where are they now? Asymmetric br?nsted acid catalyzed transfer hydrogenations
-
Asymmetric hydrogenations are of great importance in the synthesis of optically active amines. This account highlights the development of the first metal-free transfer hydrogenation that is both highly enantioselective and inspired by natures dehydrogen?ase. Further focus is given to the extension of this bioinspired process to provide a variety of valuable, biologically active products and natural products under mild reaction conditions. Georg Thieme Verlag Stuttgart - New York.
- Rueping, Magnus,Sugiono, Erli,Schoepke, Fenja R.
-
scheme or table
p. 852 - 865
(2010/07/06)
-
- Preparation of S-containing aminophosphine and phosphoramidite ligands and their applications in enantioselective C-C bond forming reactions
-
A series of phosphorus/sulfur ligands were readily prepared and successfully applied in the Pd-catalyzed enantioselective allylic substitution and Cu-catalyzed conjugated additions of cyclic enones, respectively. The Pd-catalyzed enantioselective allylic
- Zeng, Ju-Lan,Yu, Sai-Bo,Cao, Zhong,Yang, Dao-Wu
-
experimental part
p. 243 - 248
(2010/08/22)
-
- Copper-catalyzed asymmetric 1,4-conjugate addition of dialkylzinc to enones
-
Asymmetric 1,4-conjugation addition of dialkylzinc (diethylzinc and dimethylzinc) to cyclic enones, chalcone and nitroalkenes was achieved by a 25 mol% (R)-6,6'-Br2-BINOL(1f), 25 mol% CuSPh and 100 mol% dicyclohexylmethylamin(Cy2NMe) catalyst system. The Cu(I) catalyst system enables the cyclic enone, chalcone and nitroalkene generality with high enantioselectivity (up to84%ee) and isolated yield (up to 94%) under mild reaction conditions.
- Gou, Shaohua,Ye, Zhongbin,Shi, Leiting,Qing, Dayong,Zhang, Wen,Wang, Yuliang
-
experimental part
p. 517 - 522
(2010/10/18)
-
- Synthesis of diphosphite ligands derived from glucopyranoside and their application in the Cu-catalyzed asymmetric 1,4-addition of organozinc to enones
-
Novel chiral diphosphite ligands derived from glucopyranoside and H 8-binaphthol were synthesized, and successfully employed in the Cu-catalyzed asymmetric 1,4-addition of organozinc reagents dimethylzinc, diethylzinc, and diphenylzinc to cycli
- Zhao, Qing-Lu,Tse, Man Kin,Wang, Lai-Lai,Xing, Ai-Ping,Jiang, Xianxing
-
experimental part
p. 2788 - 2793
(2011/03/18)
-
- Synthesis of novel diphosphite ligands derived from d-mannitol and their application in Cu-catalyzed enantioselective conjugate addition of organozinc to enones
-
A series of novel chiral diphosphite ligands have been synthesized from d-mannitol derivatives and chlorophosphoric acid diary ester, and were successfully employed in the copper catalyzed enantioselective conjugate addition of organozinc reagents diethyl
- Zhao, Qing-Lu,Wang, Lai-Lai,Xing, Ai-Ping
-
experimental part
p. 2993 - 2998
(2011/03/22)
-
- Copper-catalyzed asymmetric conjugate addition with Grignard reagents and SimplePhos ligands
-
Herein we report the copper-catalyzed asymmetric conjugate addition of Grignard reagents to cyclic and acyclic enones, with SimplePhos as chiral ligands. A variety of Grignard reagents can be added to a range of cyclic and acyclic enones, with moderate to good enantioselectivities (ee's up to 86%).
- Palais, Laetitia,Alexakis, Alexandre
-
experimental part
p. 2866 - 2870
(2010/04/05)
-
- ORGANIC SALTS AND METHOD FOR PRODUCING CHIRAL ORGANIC COMPOUNDS
-
The invention relates to a method for producing chiral organic compounds by asymmetric catalysis, using ionic catalysts comprising a chiral catalyst anion. The claimed method is suitable for reactions which are carried out over cationic intermediate stages, such as iminium ions or acyl pyridinium ions. The invention enables the production of chiral compounds with high ee values, that until now could only be obtained by means of costly purification methods.
- -
-
Page/Page column 7; 8
(2009/02/11)
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- New bis(1-ferrocenylethyl)amine-derived monodentate phosphoramidite ligands for highly enantioselective copper-catalyzed 1,4-conjugate addition
-
A new family of chiral bis(1-ferrocenylethyl)amine-derived monodentate phosphoramidite ligands has been prepared and successfully applied in the Cu-catalyzed asymmetric 1,4-conjugate addition of diethylzinc to a variety of α,β-unsaturated compounds, in wh
- Zou, Dong-Yun,Duan, Zheng-Chao,Hu, Xiang-Ping,Zheng, Zhuo
-
supporting information; experimental part
p. 235 - 239
(2009/06/06)
-
- Synthesis of copper(I) complexes of N-heterocyclic carbene-phenoxyimine/ amine ligands: Structures of mononuclear copper(II), mixed-valence copper(I)/(II), and copper(II) cluster complexes
-
Copper(I) bromide complexes (2a and 2b) of NHC-phenol-imine ligand precursors {3-[(1R,2R)-2-{[1-(3,5-di-tert-butyl-2-hydroxyphenyl)meth-(E)- ylidene] amino}cyclohexyl] -1-iso-propyl-4-phenyl-3H-imidazol-1-ium bromide (1a) and 3-[(1R,2R)-2-{[1-(2-hydroxyphenyl)meth-(E)-ylidene] amino}-cyclohexyl] -1-isopropyl-4-phenyl-3H-imidazol-1-ium bro-mide (1b), respectively} have been prepared. Complexes 2aand 2b exhibit copper coordination only through the carbenecarbon atom (C) and do not spontaneously eliminate HBr togive additional phenoxyimine (NO) bonds, which is attrib-uted to intramolecular hydrogen bonding. Crystallisation of2a and 2b gives 2a-and 2b-, respectively, that contain (C) copper(I) bromide and (NO)2 copper(II) coordination. Com-plex 2b-also exhibits intermolecular CuIBr interactions giv-ingaCu2Br2 bridge that links two molecules of 2b resulting in an ellipse motif. Reduction of the ligand precursor iminegroup of 1a allows synthesis of silver(I) and copper(I) NHC-phenolamine complexes 6 and 7, respectively, that also retainthe phenol hydrogen atom. Attempts to selectively prepare2a-gave a copper(II) complex 9 that exhibits an (NO)2CuIIstructure with pendant imidazolium salt groups. Reaction be-tween the silver(I) bromide derivative of 1a and CuCl2·2H2Ogives a complex derived from a Cu6(O)(OH)4Cl3 core and two(NO) and one (CNO) ligands, respectively. The use of 2a and7 as precatalysts for 1,4-conjugate addition to enones andaziridination of alkenes was studied, showing that, whilstboth catalysts are active, enantioselectivities are low, whichis attributed to the lack of Cu-(NO) coordination. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009.
- Simonovic, Stevan,Whitwood, Adrian C.,Clegg, William,Harrington, Ross W.,Hursthouse, Michael B.,Male, Louise,Douthwaite, Richard E.
-
experimental part
p. 1786 - 1795
(2009/09/06)
-
- Novel N,N,P-tridentate ligands for the highly enantioselective copper-catalyzed 1,4-addition of dialkylzincs to enones
-
(Chemical Equation Presented) Use of 0.25 mol % of the N,N,P-tridentate ligand containing the 2-quinolyl moiety (1 and 2) and 0.1 mol % of Cu(OTf) 2 enabled the enantioselective 1,4-addition of dialkylzincs to cyclic enones to produce 1,4-adduc
- Kawamura, Kenjiro,Fukuzawa, Hitomi,Hayashi, Masahiko
-
supporting information; scheme or table
p. 3509 - 3512
(2009/05/07)
-
- Cu-catalyzed enantioselective conjugate addition of diethylzinc to cyclic enones with chiral phosphite ligands derived from 1,2:5,6-di-O-cyclohexylidene-d-mannitol
-
A new and readily in situ prepared catalytic system of copper salts with chiral P,N-ligands or aryl diphosphite ligand, which derived from 1,2:5,6-di-O-cyclohexylidene-d-mannitol, 1,1′-binaphthol, and phenyl isocyanate derivatives, were successfully emplo
- Zhao, Qing-Lu,Wang, Lai-Lai,Kwong, Fuk Yee,Chan, Albert S.C.
-
p. 1899 - 1905
(2008/02/11)
-
- Enantioselective conjugate addition of dialkylzinc to cyclic enones catalyzed by chiral binaphthyldiamine-copper(I) complexes
-
The enantioselective conjugate addition of dialkylzinc (R2Zn) to cyclic enones was examined using chiral binaphthyldiamine-copper(I) catalysts. Under the present reaction conditions, chiral C2-symmetric [RZn(II)]2-diamine-
- Hatano, Manabu,Asai, Takafumi,Ishihara, Kazuaki
-
p. 8590 - 8594
(2008/03/30)
-
- Highly enantioselective transfer hydrogenation of α,β- unsaturated ketones
-
We describe an efficient and highly enantioselective conjugate transfer hydrogenation of α,β-unsaturated ketones that is catalyzed by a salt made from tert-butyl valinate and a recently introduced powerful chiral phosphoric acid catalyst (TRIP). Copyright
- Martin, Nolwenn J. A.,List, Benjamin
-
p. 13368 - 13369
(2007/10/03)
-
- Application of chiral ionic liquids in the copper catalyzed enantioselective 1,4-addition of diethylzinc to enones
-
Copper catalyzed enantioselective addition of diethylzinc to various enones has been achieved in the presence of a new class of chiral ionic liquid (ChirILs) derived from α-pinene. This first study on the application of ChirILs for the title reaction show
- Malhotra, Sanjay V.,Wang, Yun
-
p. 1032 - 1035
(2007/10/03)
-
- Highly enantioselective copper-catalyzed conjugate addition of diethylzinc to cyclic enones with spirocyclic phosphoramidite ligands
-
A series of spirocyclic phosphoramidite ligands 6-9 with different substituents on the amine moiety were synthesized from the chiral spirocyclic diol (R)-5. These monodentate ligands have been applied in copper-catalyzed conjugate addition of diethylzinc
- Zhang, Weicheng,Wang, Chun-Jiang,Gao, Wenzhong,Zhang, Xumu
-
p. 6087 - 6090
(2007/10/03)
-
- Asymmetric reduction of α,β-unsaturated carbonyl compounds with reductases from Nicotiana tabacum
-
Two reductases, p44 and p90, isolated from Nicotiana tabacum, catalyzed the asymmetric reduction of α,β-unsaturated carbonyl compounds. The p44 reductase reduced α-alkylated enones to (R)-ketones, while the reduction using the p90 reductase gave the (S)-k
- Shimoda, Kei,Kubota, Naoji,Hamada, Hiroki
-
p. 2443 - 2446
(2007/10/03)
-
- Highly enantioselective copper-catalyzed 1,4-conjugate addition of diethylzinc to cyclic enones and αβ-unsaturated lactones
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A significant improvement in enantioselectivity has been achieved in the 1,4-additions of diethylzinc to 2-cyclopentenone, 2-cyclohexenone and 5,6-hydro-2H-pyran-2-one (up to 93%, 98% and 94% ee, respectively) by using a chiral diphosphite-copper catalyst under suitable reaction conditions.
- Liang, Liang,Yan, Ming,Li, Yue-Ming,Chan, Albert S.C.
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p. 2575 - 2578
(2007/10/03)
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- Enantioselective conjugate addition of dialkylzinc and diphenylzinc to enones catalyzed by a chiral copper(I) binaphthylthiophosphoramide or binaphthylselenophosphoramide ligand system
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The enantioselective conjugate addition of dialkylzinc or diphenylzinc to enones was catalyzed by a copper(I)-axially chiral binaphthylthiophosphoramide or binaphthylselenophosphoramide ligand system at room temperature (20°C) or 0°C, affording the Michae
- Shi, Min,Wang, Chun-Jiang,Zhang, Wen
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p. 5507 - 5516
(2007/10/03)
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- Synthesis of new chiral aryl diphosphite ligands derived from pyranoside backbone of monosacharides and their application in copper-catalyzed asymmetric conjugate addition of diethylzinc to cyclic enones
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New chiral aryl diphosphite ligands based on the pyranoside backbones of glucose and galactose were prepared. These ligands were tested in the Cu-catalyzed asymmetric conjugate addition of diethyl-zinc to cyclic enones with up to 88% ee. The stereoselecti
- Wang, Lailai,Li, Yue-Ming,Yip, Chiu-Wing,Qiu, Liqin,Zhou, Zhongyuan,Chan, Albert S. C.
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p. 947 - 953
(2007/10/03)
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- OPTICALLY ACTIVE PHOSPHITES AND PHOSPHORAMIDITES BEARING BIPHENOL SKELETONS WITH AXIAL CHIRALITY, AND THEIR USE IN CATALYTIC ASYMMETRIC REACTIONS
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Novel optically active ligands which are mondentate phosphites and phosphoramidites, and bidentate phosphites and phosphoramidites; optically active catalysts comprising a reaction mixture of the ligand and a transition metal or its compound; and processes of using the optically active catalysts to produce optically active compounds.
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Page/Page column 74; 76
(2010/12/01)
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- Cyclic ketones, their preparation and their use in the synthesis of amino acids
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A method is provided for making an enantiomerically pure of the formula: in which R and R′ represent C1?C10 alkyl, C2?C10 alkenyl or C3?C10 cycloalkyl and the wedges signify (S)- or (R)-stereochemistry, the substituents in compound (II) being trans. Conjugate addition is carried out between an organometallic nucleophile that provides a group R as defined above and (R)-4-acetoxycyclopent-2-en-1-one, (S)-4-acetoxycyclopent-2-en-1-one or a similar compound in which acetoxy is replaced by another leaving group to give, e.g. in the case of the acetoxy compound, a trans 3,4-disubstituted addition product of formula III or IV; The acetyl group is eliminated from the addition product to give an (R)- or (S)-4-alkyl or 4-alkenyl cyclopent-2-en-1-one the compound of formula is then to be hydrogenated to give a cyclopentanone of formula (I) or conjugate addition of a second organometallic nucleophile that provides a group R′ as defined above to the compound of the above formula may be carried out to give a trans 3,4-disubstituted addition product of formula (II). One of the above compounds may be converted e.g. via an intermediate (XV)-(XVIII) (in which the substituents R and R′ and the wedges have the meanings indicated above) to a gabapentin analogue of one of the formulae shown below: in which the substituents R and R′ and the wedges also have the meanings indicated above.
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- Copper-catalyzed enantioselective conjugate addition of triethylaluminum to 2-cyclopentenone
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Bidentate phosphites were prepared starting from BINOL, H8-BINOL or 3,3′, 5,5′-tetra-tert-butyl-2,2′-biphenol. Utilization of these ligands in the copper-catalyzed enantioselective conjugate addition of triethylaluminum to 2-cyclopentenone affo
- Su, Liming,Li, Xingshu,Chan, Wing Lai,Jia, Xian,Chan, Albert S. C.
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p. 1865 - 1869
(2007/10/03)
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- Copper-catalyzed enantioselective conjugate addition of dialkylzinc reagents to enones with new peptidyl phosphane ligands
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Copper catalysts based on new peptidyl phosphane ligands have been developed for enantioselective conjugate additions of dialkylzinc reagents to cyclic enones. Enantioselectivities greater than 97% ee have been observed.
- Breit, Bernhard,Laungani, Andy Ch.
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p. 3823 - 3826
(2007/10/03)
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- Highly Enantioselective 1,4-Addition of Diorganozinc Reagents to Cyclic Enones Using Chiral Diphosphite Ligands Derived from H8-Binaphthol
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(Matrix Presented) High enantioselectivities have been achieved in the 1,4-addition of dialkylzincs to 2-cyclopentenone, 2-cyclohexenone, and 2-cycloheptenone with ee values up to 99% by using chiral aryl diphosphite ligands derived from H8-binaphthol.
- Liang, Liang,Au-Yeung, Terry T.-L.,Chan, Albert S. C.
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p. 3799 - 3801
(2007/10/03)
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- Discovery of a new efficient chiral ligand for copper-catalyzed enantioselective Michael additions by high-throughput screening of a parallel library
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A combinatorial library of 125 chiral Schiff base ligands 5 was synthesized with the use of solutionphase parallel synthesis and solid-phase extraction (SPE) techniques to scavenge excess reagents and reaction by-products and avoid chromatography. The syn
- Chataigner, Isabelle,Gennari, Cesare,Ongeri, Sandrine,Piarulli, Umberto,Ceccarelli, Simona
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p. 2628 - 2634
(2007/10/03)
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- New chiral oxazoline-phosphite ligands for the enantioselective copper- catalyzed 1,4-addition of organozinc reagents to enones
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A series of new P,N-ligands with a binaphthyl and an oxazoline moiety were prepared, which are efficient ligands for the enantioselective copper- catalyzed 1,4-addition of organozinc reagents to enones. Increasing the steric bulk in the 3,3'-position of binaphthyl from an H to a biphenylyl moiety improved the ee from 65 to 94% in the reaction of diethylzinc with cyclopentenone. (C) 2000 Elsevier Science Ltd.
- Escher, Iris H.,Pfaltz, Andreas
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p. 2879 - 2888
(2007/10/03)
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