- Troeger's base-functionalised organic nanoporous polymer for heterogeneous catalysis
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An organic nanoporous polymer (BET surface area of 750 m2 g -1) containing bicovalently-bonded Troeger's base as functional moieties in the network was synthesized, characterised, and further applied as a promising heterogeneous catalyst in the addition reaction of diethylzinc to aromatic aldehyde. The Royal Society of Chemistry 2010.
- Du, Xin,Sun, Yalei,Tan, Bien,Teng, Qingfeng,Yao, Xiaojun,Su, Chengyong,Wang, Wei
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Read Online
- Cluster-organic framework materials as heterogeneous catalysts for high efficient addition reaction of diethylzinc to aromatic aldehydes
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To explore the catalytic activity of heterometallic cluster-organic frameworks, three 3d-3d heterometallic cluster-organic frameworks based on the cooperative assembly of tetrahedral Cu4I4 and metal-carboxylate clusters with potential open metal sites were synthesized and described in detail. The structure of 1 consists of tetrahedral [Cu 4I4(INA)4]4- metalloligands (INA = isonicotinate) linking unusual Zn8(μ4-O)(COO) 12(H2O)4 clusters into a (4,12)-connected network. Compound 2 features a 2-fold interpenetrating 4-connected bbf-type framework based on new [Cu4I4(INA)2(DBO) 2]2- metalloligands (DBO = 1,4-diazabicyclo[2.2.2]octane) and paddle-wheel Zn2(COO)4 units. The 2-fold interpenetrating diamond-type framework 3 is constructed from tetrahedral [Cu4I4(INA)4]4- metalloligand and Mn2(COO)4(H2O)2(DMF) unit with potential open Mn centers. All three framework materials have notable catalytic activity on the diethylzinc addition to aromatic aldehydes, and the catalytic properties of compound 1 have been studied in detail. The results reveal that the heterogeneous catalysis of the diethylzinc addition to aromatic aldehydes by using cluster-organic framework as catalyst is determined by several experimental factors, such as temperature, reaction time, and the incorporation of electron-withdrawing groups in aromatic aldehydes.
- Tan, Yan-Xi,He, Yan-Ping,Zhang, Jian
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Read Online
- An asymmetric catalytic carbon-carbon bond formation in a fluorous biphasic system based on perfluoroalkyl-BINOL
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Asymmetric diethylzinc addition to arylaldehydes in a fluorous biphasic system catalyzed by perfluoroalkyl-BINOL has been accomplished. (C) 2000 Elsevier Science Ltd.
- Tian,Kin Shing Chan
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Read Online
- Grignard reagents in ionic liquids
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Grignard reagents were generated from magnesium and organic iodides in the ionic liquid n-butylpyridinium tetrafluoroborate, [bpy][BF4], and they showed different reactivity from classical Grignard reagents in organic solvents. The Royal Society of Chemistry 2006.
- Law, Man Chun,Wong, Kwok-Yin,Chan, Tak Hang
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Read Online
- Copper-Catalyzed Enantioconvergent Cross-Coupling of Racemic Alkyl Bromides with Azole C(sp2)?H Bonds
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The development of enantioconvergent cross-coupling of racemic alkyl halides directly with heteroarene C(sp2)?H bonds has been impeded by the use of a base at elevated temperature that leads to racemization. We herein report a copper(I)/cinchona-alkaloid-derived N,N,P-ligand catalytic system that enables oxidative addition with racemic alkyl bromides under mild conditions. Thus, coupling with azole C(sp2)?H bonds has been achieved in high enantioselectivity, affording a number of potentially useful α-chiral alkylated azoles, such as 1,3,4-oxadiazoles, oxazoles, and benzo[d]oxazoles as well as 1,3,4-triazoles, for drug discovery. Mechanistic experiments indicated facile deprotonation of an azole C(sp2)?H bond and the involvement of alkyl radical species under the reaction conditions.
- Chang, Xiao-Yong,Chen, Ji-Jun,Gu, Qiang-Shuai,Jiang, Sheng-Peng,Li, Zhong-Liang,Liu, Lin,Liu, Xiao-Dong,Liu, Xin-Yuan,Su, Xiao-Long,Wang, Fu-Li,Yang, Chang-Jiang,Ye, Liu
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supporting information
p. 380 - 384
(2020/10/30)
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- Half-sandwich rhodium complexes with phenylene-based SCS ligands: Synthesis, characterization and catalytic activities for transfer hydrogenation of ketones
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A series of half-sandwich rhodium complexes with tridentate phenylene-based bis(thione) (SCS) ligand have been synthesized and characterized. Both half-sandwich rhodium complexes and phenylene-based bis(thione) compounds were fully characterized by 1H and 13C NMR spectra, mass spectrometry and single-crystal X-ray diffraction method. The catalytic activities of half-sandwich rhodium complexes toward the transfer hydrogenation of ketones to their corresponding alcohols were explored using 2-propanol as hydrogen source and solvent. And the half-sandwich rhodium complexes exhibited high catalytic activity for transfer hydrogenation of ketones with a broad functional group tolerance.
- Jia, Wei-Guo,Gao, Li-Li,Zhi, Xue-Ting,Li, Xiao-Dong,Wang, Zhi-Bao,Sun, Ying
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- 2,2′-Bipyridine-α,α′-trifluoromethyl-diol ligand: Synthesis and application in the asymmetric Et2Zn alkylation of aldehydes
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A chiral 2,2′-bipyridine ligand (1) bearing α,α′-trifluoromethyl-alcohols at 6,6′-positions was designed in five steps affording either the R,R or S,S enantiomer with excellent stereoselectivities, i.e. 97% de, >99% ee and >99.5% de, >99.5% ee, respectively. The key step for reaching high levels of stereoselectivity was demonstrated to be the resolution of the α-CF3-alcohol using (S)-ibuprofen as the resolving agent. An initial application for the 2,2′-bipyridine-α,α′-CF3-diol ligand was highlighted in the ZnII-catalyzed asymmetric ethylation reaction of aromatic, heteroaromatic, and aliphatic aldehydes. Synergistic electron deficiency and steric hindrance properties of the newly developed ligand afforded the corresponding alcohols in good to excellent yields (up to 99%) and enantioselectivities (up to 95% ee). As observed from single crystal diffraction analysis, the complexation of the 2,2′-bipyridine-α,α′-CF3-diol ligand generates an unusual hexacoordinated ZnII.
- Lauzon, Samuel,Ollevier, Thierry
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supporting information
p. 11025 - 11028
(2021/11/03)
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- Regiodivergent Hydroborative Ring Opening of Epoxides via Selective C-O Bond Activation
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A magnesium-catalyzed regiodivergent C-O bond cleavage protocol is presented. Readily available magnesium catalysts achieve the selective hydroboration of a wide range of epoxides and oxetanes yielding secondary and tertiary alcohols in excellent yields and regioselectivities. Experimental mechanistic investigations and DFT calculations provide insight into the unexpected regiodivergence and explain the different mechanisms of the C-O bond activation and product formation.
- Magre, Marc,Paffenholz, Eva,Maity, Bholanath,Cavallo, Luigi,Rueping, Magnus
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supporting information
p. 14286 - 14294
(2020/09/15)
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- Efficient Transfer Hydrogenation of Ketones using Methanol as Liquid Organic Hydrogen Carrier
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Herein, we demonstrate an efficient protocol for transfer hydrogenation of ketones using methanol as practical and useful liquid organic hydrogen carrier (LOHC) under Ir(III) catalysis. Various ketones, including electron-rich/electron-poor aromatic ketones, heteroaromatic and aliphatic ketones, have been efficiently reduced into their corresponding alcohols. Chemoselective reduction of ketones was established in the presence of various other reducible functional groups under mild conditions.
- Garg, Nidhi,Paira, Soumen,Sundararaju, Basker
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p. 3472 - 3476
(2020/05/29)
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- Rhodium coordination compound as well as preparation method and application thereof
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The invention discloses a rhodium coordination compound as well as a preparation method and application thereof. The structure of the rhodium coordination compound is shown as a formula I which is described in the specification, wherein R is one of H and C1-C6 alkyl, and X is halogen. The rhodium coordination compound can efficiently catalyze a carbonyl transfer hydrogenation reaction to obtain corresponding alcohol, and meanwhile, the preparation method has the advantages of simple process and simplicity and convenience in operation.
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Paragraph 0130-0132
(2020/09/09)
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- Method for synthesizing secondary alcohol
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The invention discloses a method for synthesizing secondary alcohol, which utilizes transition metal catalysis and uses isopropanol as a hydrogen source to synthesize the secondary alcohol. The reaction not only uses inexpensive and environmentally friendly isopropanol as the hydrogen source and a solvent, but also has the advantages of high yield, environmental protection, and the like, and therefore the reaction has broad development prospects.
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Paragraph 0114; 0115; 0116; 0117
(2019/03/15)
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- Ruthenium(II)-Catalyzed β-Methylation of Alcohols using Methanol as C1 Source
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Selective introduction of methyl branches into the carbon chains of alcohols can be achieved with low loadings of ruthenium precatalyst [RuH(CO)(BH4)(HN(C2H4PPh2)2)] (Ru-MACHO-BH) using methanol both as methylating reagent and as reaction medium. A wide range of structurally divers alcohols was β-methylated with excellent selectivity (>99 %) in fair to high yields (up to 94 %) under standard conditions, and turnover numbers up to 18,000 could be established. The overall reaction rate of the complex catalytic network appears to be governed by interconnection of the individual subcycles through availability of the reactive intermediates. The synthetic procedure opens pathways to important structural motifs following the Green Chemistry principles.
- Kaithal, Akash,Schmitz, Marc,H?lscher, Markus,Leitner, Walter
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p. 5287 - 5291
(2019/05/28)
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- NBS-mediated synthesis of β-keto sulfones from benzyl alcohols and sodium arenesulfinates
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An efficient synthetic route towards the synthesis of β-keto sulfones has been developed from secondary benzyl alcohols using N-bromosuccinimide (NBS). The present protocol utilizes NBS as oxidant as well as brominating agent, readily accessible benzyl alcohols and sodium arenesulfinates as the sulfonylating reagent under mild conditions. The control experiments revealed that the reaction proceeds via oxidation of alcohol to ketone, α-bromination of ketone and nucleophilic substitution by sodium arenesulfinate. Furthermore, the efficiency of the methodology was tested with a gram scale reaction and also shown the synthetic utility.
- Muneeswara, Madithedu,Sundaravelu, Nallappan,Sekar, Govindasamy
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supporting information
p. 3479 - 3484
(2019/05/21)
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- Chiral zinc amidate catalyzed additions of diethylzinc to aldehydes
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A series of bifunctional spiro ligands bearing “carboxamide–phosphine oxide” groups and ethylzinc carboxamidates from these ligands as catalysts for Et2Zn additions to aldehydes were reported. Excellent yields were obtained with moderate ee′s in Et2Zn additions to benzaldehyde derivatives, implying effectiveness of our newly designed catalytic structures as well as mediocre stereocontrol by these chiral ligands. Possible transition states were suggested based on the crystal structures of two ligands.
- Zhang, Jinxia,Li, Shasha,Zheng, Xinxin,Li, Hongjie,Jiao, Peng
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supporting information
p. 1913 - 1917
(2019/06/24)
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- Synthesis and Catalytic Activity of (3,4-Diphenylcyclopentadienone)Iron Tricarbonyl Compounds in Transfer Hydrogenations and Dehydrogenations
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Four (3,4-diphenylcyclopentadienone)iron tricarbonyl compounds were synthesized, and their activities in transfer hydrogenations of carbonyl compounds and transfer dehydrogenations of alcohols were explored and compared to those of the well-established [2,5-(SiMe3)2-3,4-(CH2)4(η4-C4C=O)]Fe(CO)3 (3). A new compound, [2,5-bis(3,5-dimethylphenyl)-3,4-diphenylcyclopentadienone]iron tricarbonyl (7), was the most active catalyst in both transfer hydrogenations and dehydrogenations, and compound 3 was the least active catalyst in transfer hydrogenations. Evidence was found for product inhibition of both 3 and 7 in a transfer dehydrogenation reaction, with the activity of 3 being more heavily affected. A monomeric iron hydride derived from 7 was spectroscopically observed during a transfer hydrogenation, and no diiron bridging hydrides were found under reductive or oxidative conditions. Initial results in the transfer hydrogenation of N-benzylideneaniline showed that 3 was a significantly less active catalyst in comparison to the (3,4-diphenylcyclopentadienone)iron tricarbonyl compounds.
- Funk, Timothy W.,Mahoney, Andrew R.,Sponenburg, Rebecca A.,Zimmerman, Kathryn P.,Kim, Daniel K.,Harrison, Emily E.
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supporting information
p. 1133 - 1140
(2018/04/17)
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- Chiral 2-(2-hydroxyaryl)alcohols (HAROLs) with a 1,4-diol scaffold as a new family of ligands and organocatalysts
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Efficient and modular syntheses of chiral 2-(2-hydroxyaryl)alcohols (HAROLs), novel 1,4-diols carrying one phenolic and one alcohol hydroxyl group, have been developed which led to generation of a small library of structurally diverse HAROLs in enantiomerically pure form. Of the different HAROLs examined, a HAROL based on the indan backbone exhibited the highest activity and enantioselectivity in the 1,2-addition of certain organometallic compounds to aldehydes in the presence of Ti(OiPr)4 (up to 97% y, 88% ee) and performed as a hydrogen-bond donor organocatalyst in the Morita-Baylis-Hillman reaction, promoted by trialkylphosphines.
- Dilek, ?mer,Tezeren, Mustafa A.,Tilki, Tahir,Ertürk, Erkan
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supporting information
p. 268 - 286
(2017/12/06)
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- Central-to-Helical-to-Axial-to-Central Transfer of Chirality with a Photoresponsive Catalyst
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Recent advances in molecular design have displayed striking examples of dynamic chirality transfer between various elements of chirality, e.g., from central to either helical or axial chirality and vice versa. While considerable progress in atroposelective synthesis has been made, it is intriguing to design chiral molecular switches able to provide selective and dynamic control of axial chirality with an external stimulus to modulate stereochemical functions. Here, we report the synthesis and characterization of a photoresponsive bis(2-phenol)-substituted molecular switch 1. The unique design exhibits a dynamic hybrid central-helical-axial transfer of chirality. The change of preferential axial chirality in the biaryl motif is coupled to the reversible switching of helicity of the overcrowded alkene core, dictated by the fixed stereogenic center. The potential for dynamic control of axial chirality was demonstrated by using (R)-1 as switchable catalyst to direct the stereochemical outcome of the catalytic enantioselective addition of diethylzinc to aromatic aldehydes, with successful reversal of enantioselectivity for several substrates.
- Pizzolato, Stefano F.,?tacko, Peter,Kistemaker, Jos C. M.,Van Leeuwen, Thomas,Otten, Edwin,Feringa, Ben L.
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supporting information
p. 17278 - 17289
(2019/01/04)
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- Halogen-bonded iodonium ion catalysis: A route to α-hydroxy ketones: Via domino oxidations of secondary alcohols and aliphatic C-H bonds with high selectivity and control
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A domino synthesis of α-hydroxy ketones has been developed from benzylic secondary alcohols employing catalytic iodonium ions stabilized by DMSO. The reaction proceeds through an unprecedented sequential oxidation of alcohols to ketone and its α-hydroxylation in a controlled manner. The spectroscopic evidence establishes the possibility of formation of a stable halogen-bonded adduct between DMSO and iodonium ions.
- Guha, Somraj,Kazi, Imran,Mukherjee, Pranamita,Sekar, Govindasamy
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supporting information
p. 10942 - 10945
(2017/10/13)
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- Pure phosphotriesters as versatile ligands in transition metal catalysis: efficient hydrosilylation of ketones and diethylzinc addition to aldehydes
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This work aims to highlight the underrated role played by pure phosphotriester (or phosphate) ligands in catalysis, when compared to other phosphorus-containing donors such as phosphane oxides or phosphites. To probe this and to enlarge the very narrow catalytic scope of these Lewis bases, easily accessible mono- and bidentate phosphotriesters were tested as donors in two important transition metal-based catalytic transformations: the zinc-catalyzed hydrosilylation of ketones and the titanium-promoted diethylzinc addition to aldehydes. In both cases, the reactions were successful and the corresponding alcohols were obtained in high yields.
- Bouhachicha,Ngo Ndimba,Roisnel,Lalli,Argouarch
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p. 4767 - 4770
(2017/07/11)
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- OXADIAZINE COMPOUNDS AND METHODS OF USE THEREOF
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The present disclosure relates to oxadiazine compounds, pharmaceutical compositions comprising an effective amount of an oxadiazine compound and methods for using an oxadiazine compound in the treatment of a neurodegenerative disease, comprising administering to a subject in need thereof an effective amount of an oxadiazine compound.
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Paragraph 0774
(2017/03/14)
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- Mechanistic implications of the enantioselective addition of alkylzinc reagents to aldehydes catalyzed by nickel complexes with α-amino amide ligands
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The enantioselective alkylation of aldehydes catalysed by nickel(ii)-complexes derived from α-amino amides was studied by means of density functional theory (DFT) and ONIOM (B3LYP:UFF) calculations. A mechanism was proposed in order to investigate the origin of enantioselectivity. The chirality-determining step for the alkylation was the formation of the intermediate complexes with the involvement of a 5/4/4-fused tricyclic transition state. The predominant products predicted theoretically were of (S)-configuration, in good agreement with experimental observations. The scope of the reaction was examined and high yields and enantioselectivities were observed for the enantioselective addition of Et2Zn and Me2Zn to aromatic and aliphatic aldehydes.
- Escorihuela, Jorge,Burguete, M. Isabel,Ujaque, Gregori,Lledós, Agustí,Luis, Santiago V.
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supporting information
p. 11125 - 11136
(2016/12/07)
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- Bu4NI-Catalyzed α-Oxyacylation of Carbonyl Compounds with Toluene Derivatives
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A TBAI (tetrabutylammonium iodide)-catalyzed direct α-oxyacylation of carbonyl compounds from readily available toluene derivatives has been developed. The distinguished features of this metal-free protocol include the employment of simple starting material, a wide carbonyl compound scope, and mild reaction conditions.
- Li, Chengliang,Jin, Tao,Zhang, Xinglu,Li, Chunju,Jia, Xueshun,Li, Jian
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supporting information
p. 1916 - 1919
(2016/05/19)
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- A versatile and one-pot strategy to synthesize ?±-amino ketones from benzylic secondary alcohols using N -bromosuccinimide
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A metal-free one-pot strategy has been developed for the first time to synthesize pharmaceutically important ?±-amino ketones from readily available benzylic secondary alcohols and amines using N-bromosuccinimide. This new reaction proceeds via three consecutive steps involving oxidation of alcohols, ?±-bromination of ketones, and nucleophilic substitution of ?±-bromo ketones to give ?±-amino ketones. Importantly, this novel one-pot greener reaction avoids direct usage of toxic and corrosive bromine. This methodology has been employed efficiently to synthesize pharmaceutically important amfepramone and pyrovalerone in a single step.
- Guha, Somraj,Rajeshkumar, Venkatachalam,Kotha, Surya Srinivas,Sekar, Govindasamy
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supporting information
p. 406 - 409
(2015/03/04)
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- Novel chiral N,N′-dimethyl-1,4-piperazines with metal binding abilities
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With the objective of developing novel chiral ligands, we report an efficient strategy to prepare chiral N,N-dimethyl-1,4-piperazines, six-member heterocyclic molecules that possess metal binding features. We prepared and characterized 18 piperazines, and evaluated their ability to complex different mono- and divalent metals, using a rapid picrate extraction technique. Some newly prepared diamine ligands were used in diethylzinc alkylation of aryl aldehydes. Yields increased significantly in the presence of the diamine ligands, though enantioselectivity was low. The results demonstrate the validity of the approach for preparing and identifying useful chiral diamine ligands.
- Bérubé, Christopher,Cardinal, Sébastien,Boudreault, Pierre-Luc,Barbeau, Xavier,Delcey, Nicolas,Giguère, Martin,Gleeton, Dave,Voyer, Normand
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p. 8077 - 8084
(2015/12/30)
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- A catalytic system for the activation of diorganozinc reagents
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We report a novel catalytic system for the activation of diorganozinc reagents. We assumed that the nucleophilic activation of diethylzinc should be efficiently performed by simple alkali metal salts. Indeed, the combination of sodium salts and 15-crown-5 significantly accelerates the rate of diethylzinc addition to benzaldehyde under mild conditions. The activity of the catalytic system strongly depends on the nature of the anion, decreasing in the order I->Br->Cl->F-. Under the optimized reaction conditions, various aryl, hetero aryl, and aliphatic aldehydes were converted with diethylzinc and the corresponding product was obtained in excellent yields. The first X-ray absorption spectroscopy measurements on such type of reactions provide initial insights that support the proposed catalytic cycle and suggest the formation of a zincate complex.
- Werner, Thomas,Bauer, Matthias,Riahi, Abdol Majid,Schramm, Heiko
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p. 4876 - 4883
(2014/08/05)
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- Synthesis of 1,3-aminonaphthols by diastereoselective Betti-type aminoalkylation of dihydroxy naphthalenes; Diastereoselectivity, absolute configuration, and application
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Dihydroxy naphthalenes have been applied in Betti-type solventless condensation between aldehydes and (S)-phenylethylamine as a chiral auxiliary. A series of chiral 1,3-aminonaphthols has been synthesized and isolated in diastereoisomerically pure form. The absolute configurations of the aminonaphthols synthesized have been determined by means of advanced NMR experiments and confirmed by X-ray crystallography. The new chiral aminonaphthols have been tested as pre-catalysts for the addition of diethyl zinc and alkynyl-Zn-reagents to aldehydes with enantioselectivities of up to 98% ee.
- Marinova, Maya,Kostova, Kalina,Tzvetkova, Pavleta,Tavlinova-Kirilova, Maya,Chimov, Angel,Nikolova, Rosica,Shivachev, Boris,Dimitrov, Vladimir
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p. 1453 - 1466
(2013/12/04)
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- Air-stable, nitrile-ligated (cyclopentadienone)iron dicarbonyl compounds as transfer reduction and oxidation catalysts
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A series of air-stable, nitrile-ligated (cyclopentadienone)iron dicarbonyl compounds was synthesized and their activities as catalysts in the transfer reduction of acetophenone were explored. While all were active catalysts, the acetonitrile adduct was chosen for further study and was found to be active in the transfer reduction of aldehydes and ketones and in the Oppenauer-type oxidation of secondary alcohols. The acetonitrile catalyst exhibited activities similar to those of an analogous air-sensitive iron hydride, but unlike the iron hydride it was unreactive in carbonyl reductions using hydrogen gas. Copyright
- Plank, Taylor N.,Drake, Jessica L.,Kim, Daniel K.,Funk, Timothy W.
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supporting information; experimental part
p. 597 - 601
(2012/05/04)
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- Catalytic asymmetric addition of alkyllithium reagents to aromatic aldehydes
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Herein, we report the first efficient catalytic system for the asymmetric alkylation of aldehydes with organolithium reagents in the presence of titanium(IV) isopropoxide. A variety of alkyllithium reagents can be added to aromatic aldehydes in good yields with high enantioselectivities in a simple one-pot procedure under mild conditions. Herein, we report the first efficient catalytic system for the asymmetric alkylation ofaldehydes with organolithium reagents in the presence of titanium(IV) isopropoxide. A variety of alkyllithium reagents can be added to aromatic aldehydes in good yields with high enantioselectivities in a simple one-pot procedure under mild conditions. Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
- Fernandez-Mateos, Emilio,MacIa, Beatriz,Yus, Miguel
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supporting information; body text
p. 3732 - 3736
(2012/09/21)
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- Kinetic resolution of aryl alkenylcarbinols catalyzed by Fc-PIP
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An effective kinetic resolution of a variety of aryl alkenylcarbinols catalyzed by nonenzymatic acyl transfer catalyst Fc-PIP was developed, affording corresponding unreacted alcohols in good to excellent ee value up to 99% and with selectivity factors up to 24.
- Hu, Bin,Meng, Meng,Jiang, Shanshan,Deng, Weiping
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scheme or table
p. 1289 - 1294
(2012/08/28)
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- Phosphonium salt catalyzed addition of diethylzinc to aldehydes
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The addition of diethylzinc to aromatic, heteroaromatic, and aliphatic aldehydes at room temperature is efficiently catalyzed by 1-7 mol% tetrabutylphosphonium chloride. The corresponding addition products are obtained in good to excellent yields of up to 99%. Moreover, polymer bond phosphonium salts can be used to catalyze this reaction with excellent recovery of the polymer bond catalyst up to three cycles. The application of chiral bifunctional phosphonium salts revealed a remarkable counter anion effect. Changing the anion, the activity of the tetrabutylphosphonium salt decreased in the order Cl- > Br- > I- ≈ TsO- > BF4- ≈ PF6-. However, the nature of the cation had also significant influence. Tetraalkyl-ammonium chlorides showed similar activity compared to phosphonium chlorides, while alkaline metal chlorides proved to be considerably less active. Georg Thieme Verlag Stuttgart.
- Werner, Thomas,Riahi, Abdol Majid,Schramm, Heiko
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experimental part
p. 3482 - 3490
(2011/12/04)
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- 1, 4-butanediol as a reducing agent in transfer hydrogenation reactions
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1, 4-Butanediol is able to deliver two equivalents of H2 in hydrogen- transfer reactions to ketones, imines, and alkenes. Unlike simple alcohols, which establish equilibrium in the reduction of ketones, 1, 4-butanediol acts essentially irreversibly owing to the formation of butyrolactone, which acts as a thermodynamic sink. It is therefore not necessary to use 1, 4- butanediol in great excess in order to achieve reduction reactions. In addition, allylic alcohols are reduced to saturated alcohols through an isomerization/ reduction sequence using a ruthenium catalyst with 1, 4-butanediol as the reducing agent. Imines and alkenes are also reduced under similar conditions.
- Maytum, Hannah C.,Francos, Javier,Whatrup, David J.,Williams, Jonathan M. J.
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supporting information; experimental part
p. 538 - 542
(2010/08/06)
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- N, N′-dioxide-Cu(OTf)2 complex catalyzed highly enantioselective amination reaction of N-acetyl enamide
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The N,N′-dioxide-Cu(OTf)2 complexes were applied in the asymmetric amination reaction of N-acetyl enamides with dialkyl azodicarboxylate, giving the corresponding products in good yields with high enantioselectivities (up to 91% ee). Precursors of vicinal diamine were readily obtained with excellent diastereoselectivities (>95:5) by NaBH4 reduction.
- Chang, Lu,Kuang, Yulong,Qin, Bo,Zhou, Xin,Liu, Xiaohua,Lin, Lili,Feng, Xiaoming
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supporting information; experimental part
p. 2214 - 2217
(2010/08/06)
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- A series of isoreticular chiral metalg-organic frameworks as a tunable platform for asymmetric catalysis
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Metalg-organic frameworks, built by bridging metal ions with organic linkers, represent a new class of porous hybrid materials with attractive tunability in compositions, structures and functions. In particular, the mild conditions typically employed for their synthesis allow for the functionalization of their building blocks, and thus the rational design of novel materials. Here we demonstrate the systematic design of eight mesoporous chiral metalg-organic frameworks, with the framework formula [LCu 2(solvent)2] (where L is a chiral tetracarboxylate ligand derived from 1,1'2-bi-2-naphthol), that have the same structures but channels of different sizes. Chiral Lewis acid catalysts were generated by postsynthesis functionalization with Ti(OiPr)4, and the resulting materials proved to be highly active asymmetric catalysts for diethylzinc and alkynylzinc additions, which converted aromatic aldehydes into chiral secondary alcohols. The enantioselectivities of these reactions can be modified by tuning the size of the channels, which alters the diffusion rates of the organic substrates.
- Ma, Liqing,Falkowski, Joseph M.,Abney, Carter,Lin, Wenbin
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body text
p. 838 - 846
(2010/11/17)
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- Ruthenium-catalyzed redox isomerization/transfer hydrogenation in organic and aqueous media: A one-pot tandem process for the reduction of allylic alcohols
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The hexamethylbenzene-ruthenium(ii) dimer [{RuCl(μ-Cl) (η6-C6Me6)}2] 1 and the mononuclear bis(allyl)-ruthenium(iv) complex [RuCl2(η 3:η2:η3-C12H 18)]2, associated with base and a hydrogen donor, were found to be active catalysts for the selective reduction of the CC bond of allylic alcohols both in organic and aqueous media. The process, which proceeds in a one-pot manner, involves a sequence of two independent reactions: (i) the initial redox-isomerization of the allylic alcohol, and (ii) subsequent transfer hydrogenation of the resulting carbonyl compound. The highly efficient transformation reported herein represents, not only an illustrative example of auto-tandem catalysis, but also an appealing alternative to the classical transition-metal catalyzed CC hydrogenations of allylic alcohols. The process has been successfully applied to aromatic as well as aliphatic substrates affording the corresponding saturated alcohols in 45-100% yields after 1.5-24 h. The best performances were reached using (i) 1-5 mol% of 1 or 2, 2-10 mol% of Cs2CO3, and propan-2-ol or (ii) 1-5 mol% of 1 or 2, 10-15 equivalents of NaO2CH, and water. The catalytic efficiency is strongly related to the structure of the allylic alcohol employed. Thus, in propan-2-ol, the reaction rate essentially depends on the steric requirement around the CC bond, therefore decreasing with the increasing number of substituents. On other hand, in water the transformation is favoured for primary allylic alcohols vs. secondary ones.
- Cadierno, Victorio,Crochet, Pascale,Francos, Javier,Garcia-Garrido, Sergio E.,Gimeno, Jose,Nebra, Noel
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scheme or table
p. 1992 - 2000
(2010/06/19)
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- Efficient chemoselective addition of grignard reagents to carbonyl compounds in 2-methyltetrahydrofuran
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Compared with tetrahydrofuran (THF) as a solvent for the addition reactions between Grignard reagents and carbonyl compounds 2-methyltetrahydrofuran affords the corresponding adducts in higher yields with higher chemoselectivities. Moreover, 2-methyltetrahydrofuran can be readily recycled and reused, which lowers the cost of the process and makes the reaction greener.
- Zhong, Weihui,Wu, Yaotiao,Zhang, Xingxian
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experimental part
p. 370 - 373
(2009/12/25)
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- Synthesis and biological evaluation of novel 2,4-diaminoquinazoline derivatives as SMN2 promoter activators for the potential treatment of spinal muscular atrophy
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Proximal spinal muscular atrophy (SMA) is an autosomal recessive disorder characterized by death of motor neurons in the spinal cord that is caused by deletion and/or mutation of the survival motor neuron gene (SMN1). Adjacent to SMN1 are a variable number of copies of the SMN2 gene. The two genes essentially differ by a single nucleotide, which causes the majority of the RNA transcripts from SMN2 to lack exon 7. Although both SMN1 and SMN2 encode the same Smn protein amino acid sequence, the loss of SMN1 and incorrect splicing of SMN2 have the consequence that Smn protein levels are insufficient for the survival of motor neurons. The therapeutic goal of our medicinal chemistry effort was to identify small-molecule activators of the SMN2 promoter that, by up-regulating gene transcription, would produce greater quantities of full-length Smn protein. Our initial medicinal chemistry effort explored a series of C5 substituted benzyl ether based 2,4-diaminoquinazoline derivatives that were found to be potent activators of the SMN2 promoter; however, inhibition of DHFR was shown to be an off-target activity that was linked to ATP depletion. We used a structure-guided approach to overcome DHFR inhibition while retaining SMN2 promoter activation. A lead compound 11a was identified as having high potency (EC50 = 4 nM) and 2.3-fold induction of the SMN2 promoter. Compound 11a possessed desirable pharmaceutical properties, including excellent brain exposure and long brain half-life following oral dosing to mice. The piperidine compound 11a up-regulated expression of the mouse SMN gene in NSC-34 cells, a mouse motor neuron hybrid cell line. In type 1 SMA patient fibroblasts, compound 11a induced Smn in a dose-dependent manner when analyzed by immunoblotting and increased the number of intranuclear particles called gems. The compound restored gems numbers in type I SMA patient fibroblasts to levels near unaffected genetic carriers of SMA.
- Thurmond, John,Butchbach, Matthew E. R.,Palomo, Marty,Pease, Brian,Rao, Munagala,Bedell, Louis,Keyvan, Monica,Pai, Grace,Mishra, Rama,Haraldsson, Magnus,Andresson, Thorkell,Bragason, Gisli,Thosteinsdottir, Margret,Bjornsson, Jon Mar,Coovert, Daniel D.,Burghes, Arthur H. M.,Gurney, Mark E.,Singh, Jasbir
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p. 449 - 469
(2008/09/18)
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- Screening of liver acetone powders in the resolution of 1-phenylethanols and 1-phenylpropanols derivatives
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Hydrolases from the liver acetone powders (LAPs) of bovine, cat, chicken, turkey, lamb, pig, rabbit, and rat were assessed for the enantioselective hydrolysis of acetates of 1-(4-chlorophenyl)ethanol, 1-(3-bromophenyl)ethanol, 1-(4-chlorophenyl)propanol, 1-(4-bromophenyl)propanol, and 1-(3-bromophenyl)propanol. The enantioselectivity of the hydrolytic reaction was dependent upon the liver hydrolase, substrate, pH of the reaction media, and the cosolvent. The most ester selective LAP was from chicken, and the resulting alcohols had the highest ee (80% to >99%). All of the LAPs tested catalyzed the hydrolysis of 1-(4-chlorophenyl)ethanol, except for lamb LAP.
- Solis, Aida,Garcia, Susana,Perez, Herminia I.,Manjarrez, Norberto,Luna, Hector
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p. 549 - 553
(2008/09/20)
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- Ruthenium-catalyzed reduction of allylic alcohols: An efficient isomerization/transfer hydrogenation tandem process
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A simple and highly efficient method for the selective reduction of the C=C bond in allylic alcohols has been developed using the ruthenium(ii) catalyst [{RuCl(μ-Cl)(η6-C6Me6)}2]. The Royal Society of Chemistry.
- Cadierno, Victorio,Francos, Javier,Gimeno, Jose,Nebra, Noel
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p. 2536 - 2538
(2008/02/11)
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- Selective transfer hydrogenation of carbonyl compounds by ruthenium nanoclusters supported on alkali-exchanged zeolite beta
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Selective transfer hydrogenation of aromatic ketones and β-keto esters to the corresponding alcohols was achieved by using ruthenium nanoclusters supported on alkali-exchanged zeolite beta catalyst. The high activity and selectivity of the catalyst is due to the presence of highly dispersed ruthenium clusters in combination with the large number of Bronsted acidic sites of zeolite.
- Kantam, M. Lakshmi,Rao, B. Purna Chandra,Choudary,Sreedhar
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p. 1970 - 1976
(2007/10/03)
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- The synthesis of N,O-ferrocenyl pyrrolidine-containing ligands and their application in the diethyl- and diphenylzinc addition to aromatic aldehydes
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(Chemical Equation Presented) A facile route to a series of planar chiral N,O-ferrocenyl pyrrolidine-containing ligands with varying substituents at the nitrogen and oxygen donor atoms is described. The oxygen donor atom was introduced via a diastereoselective ortho-metalation of N-methylpyrrolidinyl and N-allylpyrrolidinyl ferrocene intermediates and was quenched with various ketones. The nitrogen substituent was varied through deallylation and subsequent derivatization of a secondary pyrrolidine. The efficacy of these novel ligands was investigated in the enantioselective addition of diethylzinc and diphenylzinc to aromatic aldehydes. The ligands proved highly effective in the diethylzinc addition to benzaldehyde that resulted in high yields of up to 99% and enantioselectivities (ee's) of up to 95%. The role of planar chirality was explored and the results indicated that the planar chirality, and not the central chirality, of the ferrocenyl ligands was the dominant stereo-controlling element. Employment of a mixed ethyl-phenylzinc reagent in the phenylation of aromatic aldehydes led to a mixture of the two additional products, and the phenylated product was obtained in up to 37% ee.
- Ahern, Theresa,Mueller-Bunz, Helge,Guiry, Patrick J.
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p. 7596 - 7602
(2007/10/03)
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- Wet THF as a suitable solvent for a mild and convenient reduction of carbonyl compounds with NaBH4
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NaBH4 in wet THF can readily reduce varieties of carbonyl compounds such as aldehydes, ketones, conjugated enones, acyloins, and α-diketones to their corresponding alcohols in good to excellent yields. Reduction reactions were performed at room temperature or under reflux condition. In addition, the chemoselective reduction of aldehydes over ketones was accomplished successfully with this reducing system.
- Zeynizadeh, Behzad,Behyar, Tarifeh
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p. 307 - 315
(2007/10/03)
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- NaBH4/NaHSO4·H2O a heterogeneous acidic system for a mild and convenient reduction of carbonyl compounds under protic condition
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NaBH4 in the presence of sodium bisulfate (NaHSO 4·H2O), a weakly acidic reagent, efficiently reduces a variety of carbonyl compounds such as aldehydes, ketones, α, β-unsaturated aldehydes and ketones, α-diketones and acyloins to their corresponding alcohols in acetonitrile under heterogeneous condition. Reduction reactions were accomplished at room temperature or under reflux condition.
- Zeynizadeh, Behzad,Behyar, Tarifen
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p. 453 - 457
(2007/10/03)
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- Water as a green solvent for fast and efficient reduction of carbonyl compounds with NaBH4 under microwave irradiation
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Reduction of varieties of carbonyl compounds such as aldehydes, ketones, α,β-unsaturated aldehydes and ketones, α-diketones and acyloins was carried out very fast and efficiently by sodium borohydride in water under microwave irradiation. The corresponding product alcohols were obtained in high to excellent yields.
- Zeynizadeh, Behzad,Setamdideh, Davood
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p. 1179 - 1184
(2007/10/03)
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- Formation and reactions of alkylzinc reagents in room-temperature ionic liquids
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The presence of a suitable amount of bromide or chloride ions was found to be critical in forming the alkylzinc reagents from alkyl iodides and zinc metal in the room-temperature ionic liquid, N-butylpyridinium tetrafluoroborate. β-Hydride transfer in the reactions of butylzinc reagents with aldehydes can also be reduced by a bromide ion.
- Law, Man Chun,Wong, Kwok-Yin,Chan, Tak Hang
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p. 10434 - 10439
(2007/10/03)
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- 2,4-DIAMINOQUINAZOLINES FOR SPINAL MUSCULAR ATROPHY
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2,4-Diaminoquinazolines of formulae I-IV and VI (I, II, III, IV and VI) are useful for treating spinal muscular atrophy (SMA).
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Page/Page column 43
(2010/02/15)
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- Use of diamines containing the α-phenylethyl group as chiral ligands in the asymmetric hydrosilylation of prochiral ketones
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Chiral diamines 1-7 were used in the enantioselective hydrosilylation of prochiral aromatic and aliphatic ketones. Some of these ligands combine chiral backbones and chiral N,N′-α-phenylethyl substituents that give rise to synergistic effects between these two groups and lead to catalysts that exhibit high enantioselectivity.
- Mastranzo, Virginia M.,Quintero, Leticia,De Parrodi, Cecilia Anaya,Juaristi, Eusebio,Walsh, Patrick J.
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p. 1781 - 1789
(2007/10/03)
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- Biocatalytically assisted preparation of antifungal chlorophenylpropanols
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Fermenting baker's yeast converts 4′-chloropropiophenone 1 and 3′-chloropropiophenone 2 into enantiopure (S)-(-)-1-(4′-chlorophenyl)propan-1-ol (S)-3 and (S)-(+)-1-(3′-chlorophenyl)propan-1-ol (S)-4, respectively. Application of inhibitors and organic solvents as additives enhanced the enantiomeric excesses. Enantiopure compounds (R)-(+)-1-(4′-chlorophenyl)propan-1-ol ((R)-3) and (R)-(+)-1-(3′-chlorophenyl)propan-1-ol (R)-4 were prepared by lipase-mediated esterifications of the racemic alcohols. Maximum inhibition of the growth of the phytopathogenic fungus Botrytis cinerea was shown for the (R)-enantiomers.
- Bustillo, Antonio J.,Aleu, Josefina,Hernandez-Galan, Rosario,Collado, Isidro G.
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p. 1681 - 1686
(2007/10/03)
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- Asymmetric addition of diethylzinc to aromatic aldehydes by chiral ferrocene-based catalysts
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A series of chiral C1- and C2-symmetric ferrocenyl Schiff bases (1a-c), ferrocenyl aminoalcohols (2a), ferrocenylphosphinamides (2b-c), 1,1′-ferrocenyl-diol (3), and 1,1′-ferrocenyl-disulfonamide (4) were prepared and employed as bas
- Kim, Tae-Jeong,Lee, Hee-Yeol,Ryu, Eun-Sook,Park, Dong-Kyu,Cho, Chan Sik,Shim, Sang Chul,Jeong, Jong Hwa
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p. 258 - 267
(2007/10/03)
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- Towards more chemically robust polymer-supported chiral catalysts for the reactions of aldehydes with dialkylzincs.
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N-Methyl-alpha,alpha-diphenyl-L-prolinol derivatives with para-bromo substituents in one or both of the phenyl rings are easily bound to crosslinked polystyrene beads containing phenylboronic acid residues using Suzuki reactions. When the products were used as catalysts for the reactions of aldehydes with diethylzinc in toluene at 20 degrees C, the alcohols were produced in chemical yields >90% and with ees of upto 94%. The better of the two supported catalysts gave ees only 0-9% lower than those obtained with the corresponding soluble catalyst. One of the supported catalysts was recycled successfully nine times.
- Kell, Roger J,Hodge, Philip,Nisar, Mohammad,Watson, David
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p. 1803 - 1807
(2007/10/03)
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- Planar and central chiral [2.2]paracyclophane-based N,O-ligands as highly active catalysts in the diethylzinc addition to aldehydes
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The application of planar and central chiral [2.2]paracyclophane-based N,O-ligands in asymmetric diethylzinc additions to various aldehydes is described revealing an unusual substrate spectrum for the catalysts and their remarkably high activity.
- Dahmen, Stefan,Braese, Stefan
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- Sulfonylated aminothiazoles as new small molecule inhibitors of protein phosphatases
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Based on a previously identified lead structure, SC-ααδ9, we have developed a versatile new chemical scaffold that can be readily modified to generate libraries of both Tyr and dual specificity phosphatase inhibitors with reduced molecular weight and lipophilicity. The most potent analogue identified to date, aminothiazole 8z, inhibits the dual specificity phosphatase Cdc25B with a Ki of 4.6 ± 0.4 μM and a Hill coefficient of 2.
- Wipf, Peter,Aslan, Diana C.,Southwick, Eileen C.,Lazo, John S.
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p. 313 - 317
(2007/10/03)
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