- Solid-phase supported chiral lithium amides used in deprotonation reactions
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The lithium salt of polymer supported phenylethyl amine showed surprisingly high enantioselectivity in the asymmetric deprotonation reaction of cyclohexene oxide. The polymer supported chiral lithium amide base also proved to be more reactive compared to the free chiral lithium amide base. This is a new insight in the development and mechanism of chiral lithium amide bases used in asymmetric reactions.
- Johansson, Anna,Abrahamsson, Peter,Davidsson, Oejvind
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Read Online
- Screening and characterization of a diverse panel of metagenomic imine reductases for biocatalytic reductive amination
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Finding faster and simpler ways to screen protein sequence space to enable the identification of new biocatalysts for asymmetric synthesis remains both a challenge and a rate-limiting step in enzyme discovery. Biocatalytic strategies for the synthesis of chiral amines are increasingly attractive and include enzymatic asymmetric reductive amination, which offers an efficient route to many of these high-value compounds. Here we report the discovery of over 300 new imine reductases and the production of a large (384 enzymes) and sequence-diverse panel of imine reductases available for screening. We also report the development of a facile high-throughput screen to interrogate their activity. Through this approach we identified imine reductase biocatalysts capable of accepting structurally demanding ketones and amines, which include the preparative synthesis of N-substituted β-amino ester derivatives via a dynamic kinetic resolution process, with excellent yields and stereochemical purities. [Figure not available: see fulltext.]
- Marshall, James R.,Yao, Peiyuan,Montgomery, Sarah L.,Finnigan, James D.,Thorpe, Thomas W.,Palmer, Ryan B.,Mangas-Sanchez, Juan,Duncan, Richard A. M.,Heath, Rachel S.,Graham, Kirsty M.,Cook, Darren J.,Charnock, Simon J.,Turner, Nicholas J.
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p. 140 - 148
(2021/01/04)
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- CHIRALITY SENSING WITH MOLECULAR CLICK CHEMISTRY PROBES
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The present invention relates to an analytical method that includes providing a sample potentially containing a chiral analyte that can exist in stereoisomeric forms, and providing a probe selected from the group consisting of coumarin-derived Michael acceptors, dinitrofluoroarenes and analogs thereof, arylsulfonyl chlorides and analogs thereof, arylchlorophosphines and analogs thereof, aryl halophosphites, and halodiazaphosphites. The sample is contacted with the probe under conditions to permit covalent binding of the probe to the analyte, if present in the sample; and, based on any binding that occurs, the absolute configuration of the analyte in the sample, and/or the concentration of the analyte in the sample, and/or the enantiomeric composition of the analyte in the sample is/are determined. The probe may be a coumarin-derived Michael acceptor, a di nitrofluoroarene or analog thereof, an arylsulfonyl chloride or analog thereof, an arylchlorophosphine or analog thereof, an aryl halophosphite, or a halodiazaphosphite.
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- Direct Asymmetric Hydrogenation of N-Methyl and N-Alkyl Imines with an Ir(III)H Catalyst
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A novel cationic [IrH(THF)(P,N)(imine)] [BArF] catalyst containing a P-stereogenic MaxPHOX ligand is described for the direct asymmetric hydrogenation of N-methyl and N-alkyl imines. This is the first catalytic system to attain high enantioselectivity (up to 94% ee) in this type of transformation. The labile tetrahydrofuran ligand allows for effective activation and reactivity, even at low temperatures. Density functional theory calculations allowed the rationalization of the stereochemical course of the reaction.
- Salomó, Ernest,Gallen, Albert,Sciortino, Giuseppe,Ujaque, Gregori,Grabulosa, Arnald,Lledós, Agustí,Riera, Antoni,Verdaguer, Xavier
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supporting information
p. 16967 - 16970
(2018/12/14)
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- A general and atom-efficient continuous-flow approach to prepare amines, amides and imines via reactive N-chloramines
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Chloramines are an important class of reagents, providing a convenient source of chlorine or electrophilic nitrogen. However, the instability of these compounds is a problem which makes their isolation and handling difficult. To overcome these hazards, a continuous-flow approach is reported which generates and immediately reacts N-chloramines directly, avoiding purification and isolation steps. 2-Chloramines were produced from the reaction of styrenes with N-alkyl-N-sulfonyl-N-chloramines, whilst N-alkyl or N,N’-dialkyl-N-chloramines reacted with anisaldehyde in the presence of t-BuO2H oxidant to afford amides. Primary and secondary imines were produced under continuous conditions from the reaction of N-chloramines with base, with one example subsequently reduced under asymmetric conditions to produce a chiral amine in 94% ee.
- Jolley, Katherine E.,Chapman, Michael R.,John Blacker
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p. 2220 - 2228
(2018/09/04)
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- Selective Monomethylation of Amines with Methanol as the C1 Source
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The N-monomethyl functionality is a common motif in a variety of synthetic and natural compounds. However, facile access to such compounds remains a fundamental challenge in organic synthesis owing to selectivity issues caused by overmethylation. To address this issue, we have developed a method for the selective, catalytic monomethylation of various structurally and functionally diverse amines, including typically problematic primary aliphatic amines, using methanol as the methylating agent, which is a sustainable chemical feedstock. Kinetic control of the aliphatic amine monomethylation was achieved by using a readily available ruthenium catalyst at an adequate temperature under hydrogen pressure. Various substrates including bio-related molecules and pharmaceuticals were selectively monomethylated, demonstrating the general utility of the developed method.
- Choi, Geunho,Hong, Soon Hyeok
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supporting information
p. 6166 - 6170
(2018/04/30)
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- Imine Reductase-Catalyzed Intermolecular Reductive Amination of Aldehydes and Ketones
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Imine reductases (IREDs) have emerged as promising biocatalysts for the synthesis of chiral amines. In this study, the asymmetric imine reductase-catalyzed intermolecular reductive amination with NADPH as the hydrogen source was investigated. A highly chemo- and stereoselective imine reductase was applied for the reductive amination by using a panel of carbonyls with different amine nucleophiles. Primary and secondary amine products were generated in moderate to high yields with high enantiomeric excess values. The formation of the imine intermediate was studied between carbonyl substrates and methylamine in aqueous solution in the pH range of 4.0 to 9.0 by 1H NMR spectroscopy. We further measured the kinetics of the reductive amination of benzaldehyde with methylamine. This imine reductase-catalyzed approach constitutes a powerful and direct method for the synthesis of valuable amines under mild reaction conditions. IRED all about it: The intermolecular asymmetric reductive amination of carbonyls catalyzed by a stereoselective imine reductase produces chiral amines in high yields with high enantioselectivities. The reaction efficiency is attributed to its remarkable tolerance to high concentrations of amine nucleophiles, high pH values, high chemoselectivity towards imines, and high stereoselectivity of the biocatalyst.
- Scheller, Philipp N.,Lenz, Maike,Hammer, Stephan C.,Hauer, Bernhard,Nestl, Bettina M.
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p. 3239 - 3242
(2015/10/28)
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- Chiral molecular tweezers: Synthesis and reactivity in asymmetric hydrogenation
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We report the synthesis and reactivity of a chiral aminoborane displaying both rapid and reversible H2 activation. The catalyst shows exceptional reactivity in asymmetric hydrogenation of enamines and unhindered imines with stereoselectivities of up to 99% ee. DFT analysis of the reaction mechanism pointed to the importance of both repulsive steric and stabilizing intermolecular non-covalent forces in the stereodetermining hydride transfer step of the catalytic cycle.
- Lindqvist, Markus,Borre, Katja,Axenov, Kirill,Kótai, Bianka,Nieger, Martin,Leskel?, Markku,Pápai, Imre,Repo, Timo
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supporting information
p. 4038 - 4041
(2015/04/14)
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- Disulfonimide-Catalyzed Asymmetric Reduction of N-Alkyl Imines
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A chiral disulfonimide (DSI)-catalyzed asymmetric reduction of N-alkyl imines with Hantzsch esters as a hydrogen source in the presence of Boc2O has been developed. The reaction delivers Boc-protected N-alkyl amines with excellent yields and enantioselectivity. The method tolerates a large variety of alkyl amines, thus illustrating potential for a general reductive cross-coupling of ketones with diverse amines, and it was applied in the synthesis of the pharmaceuticals (S)-Rivastigmine, NPS R-568 Hydrochloride, and (R)-Fendiline. A chiral disulfonimide (DSI)-catalyzed asymmetric reduction of N-alkyl imines with Hantzsch esters as a hydrogen source in the presence of Boc2O was developed. The reaction delivers Boc-protected N-alkyl amines with excellent yields and enantioselectivity. The method was successfully applied to the synthesis of the pharmaceuticals (S)-Rivastigmine, NPS R-568 Hydrochloride, and (R)-Fendiline.
- Wakchaure, Vijay N.,Kaib, Philip S. J.,Leutzsch, Markus,List, Benjamin
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supporting information
p. 11852 - 11856
(2015/10/05)
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- Synthesis and characterization of chiral guanidines und guanidinium salts derived from 1-phenylethylamine
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The synthesis of two new chiral guanidines 5 and 12 and derived guanidinium salts 6, 11, 13 -15 with one and three N-(1-phenylethyl) substituents is described. In both cases, the well-precedented, reliable route via chloro-formamidines was taken. Since di
- Castiglia, Amelie,El Sehrawi, Hend M.,Orbegozo, Thomas,Spitzner, Dietrich,Claasen, Birgit,Frey, Wolfgang,Kantlehner, Willi,Jaeger, Volker
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body text
p. 337 - 346
(2012/07/14)
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- Studies on the configuration of nitrogenous stereogenic centres in adducts of rhodium(II) tetraacylates with chiral amines: the application of 1H and 13C NMR spectroscopy
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The 1H and 13C NMR spectra of enantiomerically pure amines (S)-N,N-dimethyl-1-phenylethylamine, (S)-N-methyl-1-phenylethylamine, (S)-N-ethyl-1-phenylethylamine and (S)-N-ethyl-N-methyl-1-phenylethylamine in the presence of a twofold molar excess of dirhodium(II) tetratrifluoroacetate and dirhodium(II) Mosher's acid derivatives [(4S) and (4R)] were measured in CDCl3 as a solvent. The amines having various substituents at the nitrogen atom (H, CH3 and CH2CH3) formed in such conditions as an equilibrium mixture of CSNR and CSNS 1:1 adducts. The signals of both diastereoisomers were observed in NMR spectra at either room temperature (303 K) or moderately decreased temperatures (263-273 K). The rates of mutual diastereoisomer conversion were estimated by selective inversion recovery experiments and varied from less than 0.1 to ca. 10 s-1, depending on the ligand and temperature. Analysis of 13C NMR data and NOE experimental data resulted in the unambiguous determination of the configuration at the nitrogen atom with respect to the carbon stereogenic centre. Modelling of adduct structures and calculations of molecular energy and NMR parameters (GIAO) using Density Functional Theory (DFT) were performed in order to support the experimental findings. The calculations were carried out using 3-21G//B3LYP (structure optimizing) and 311G(2d,p)/LanL2DZ//B3LYP theory levels (molecular energy and NMR shielding).
- Jazwinski, Jaroslaw,Sadlej, Agnieszka
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experimental part
p. 2331 - 2343
(2010/03/25)
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- CATALYST COMPOSITIONS AND THEIR USE IN THE DE-ENRICHMENT OF ENANTIOMERICALLY ENRICHED SUBSTRATES
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There is provided a process for the de-enrichment of enantiomerically enriched compositions which comprises reacting an enantiomerically enriched composition comprising at least a first enantiomer or diastereomer of a substrate comprising a carbon-heteroatom bond, wherein the carbon is a chiral centre and the heteroatom is a group V heteroatom, in the presence of a catalyst system and optionally a reaction promoter to give a product composition comprising first and second enantiomers or diastereomers of the substrate having a carbon-heteroatom bond, the ratio of second to first enantiomer or disatereomer in the product composition being greater than the ratio of second to first enantiomer or disatereomer in the enantiomerically enriched composition. Preferred catalyst systems include transition metal halide complex of the formula MnXpYr wherein M is a transition metal; X is a halide; Y is a neutral optionally substituted hydrocarbyl complexing group, a neutral optionally substituted perhalogenated hydrocarbyl complexing group, or an optionally substituted cyclopentadienyl complexing group; and n, p and r are integers. The reaction promoter is preferably a halide salt.
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Page/Page column 13-15
(2008/06/13)
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- ASYMMETRIC IMINE HYDROGENATION PROCESSES
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A process for the catalytic hydrogenation or asymmetric hydrogenation of imines of Formula (I) to the corresponding amines of Formula (II) is provided in which R1 is aryl ; R2 is aryl, cyclic, alkyl, alkenyl or alkynyl; and R3 is alky l. The catalytic system includes a ruthenium complex containing (1) a diamine and (2) a diphosphine or two monodentate phosphines ligands. Such process also relates to the asymmetric hydrogenation of prochiral imines to the chiral amines using chiral ruthenium complexes bearing chiral diphosphines or chiral monodentate phosphines and chiral diamines.
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Page/Page column 27
(2008/06/13)
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- Asymmetric reduction of ketoxime derivatives and N-alkylketimines with borane-oxazaborolidine adducts
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Oxime ethers of acetophenone, isopropyl methyl ketone, and tert-butyl methyl ketone were reduced to the corresponding hydroxylamine ethers of 45-94% ee with borane-oxazaborolidine 1 derived from (-)-norephedrine. A one-pot reduction of acetophenone oxime with 1 to 1-phenylethylhydroxylamine of 87% ee is described. The reduction of 6-methyl-2,3,4,5-tetrahydropyridine and N-methylimines of the above mentioned ketones with borane-B-methyloxazaborolidine adduct 2, derived from (-)-diphenylprolinol, gave the corresponding amines of 40-74% ee.
- Krzeminski, Marek P.,Zaidlewicz, Marek
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p. 1463 - 1466
(2007/10/03)
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- Synthesis of N-Methyl-N-{(1S)-1-[(3R)-pyrrolidin-3-yl]ethyl} amine
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N-Methyl-N-{(1S)-1-[(3R)-pyrrolidin-3-yl]ethyl} amine (1)1 is a key intermediate in the preparation of premafloxacin (2), which was under development as an antibiotic for use against pathogens of veterinary importance. This paper describes the development of a practical, efficient, and stereoselective process for the preparation of 1 from isobutyl (3S)-3-{methyl[(1S)-1-phenylethyl]-amino}butanoate (5c). The key steps in the synthetic sequence are an asymmetric Michael addition, which yields 5c, and a stereoselective alkylation, which yields (3S,4S)-3-allyl-1,4-dimethylazetidin-2-one (17).
- Fleck, Thomas J.,McWhorter Jr., William W.,DeKam, Richard N.,Pearlman, Bruce A.
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p. 9612 - 9617
(2007/10/03)
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- 1,5-Asymmetric Induction in Squarate Cascades. Conformational Control of Helicity by Chiral Amino Substituants during Conrotatory Octatetraene Cyclization Prior to β-Elimination
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Both the sigmatropic and electrocyclic rearrangement pathways that can arise when a pair of alkenyl anions are added to a squarate ester have high stereochemical demands. The distinction is nontrivial. When cis addition occurs initially, the stereoinduction that materializes at this point is fully transmitted into the product (s). The more commonly observed trans addition exhibits fleeting stereochemical consequences because of rapid equilibration of the octatetraenyl intermediates. In this instance, product distribution is governed by the relative rates of conrotatory cyclization at this advanced stage. Herein reported is a complete dissection of a squarate cascade when a stereogenic center attached to an amino substituent effects 1,5-asymmetric induction prior to β-elimination of the entire fragment. Deuterium labeling permits a direct measure of the contrasting kinetic imbalances associated with the two possible modes of alkenyl anion addition. Furthermore, quantitative analysis of the partitioning experienced by the two helical octatetraenes is readily accomplished. This work constitutes the first example where a complete dynamic profile for these complex processes has been possible. The fact that long-range asymmetric induction has been instrumental in solving the mechanistic puzzle is noteworthy.
- Paquette, Leo A.,Tae, Jinsung
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p. 2022 - 2030
(2007/10/03)
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- The effects of the nature of catalyst and of the solvent on the stereoselectivity in amine-catalyzed asymmetric synthesis of substituted cyclohexa-1,3-dienes from prenal and monoesters of ylidenemalonic acids
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In the amine-catalyzed reactions of prenal with (Z)-5-methyl-2-(methoxycarbonyl)hexa-2,4-dienoic or (Z)-3-phenyl-2-(ethoxycarbonyl)prop-2-enoic acid chiral β-amino alcohols provide for higher enantiomeric purity of the resulting alkyl 4-methyl-6-(2-methylprop-1-enyl)- and 4-methyl-6-phenylcyclohexa-1,3-dienoates than that provided by related chiral amines without hydroxy group. The values of ee attained in nonpolar solvents are higher than those observed in the polar ones. Substituting stoichiometric amounts of a chiral 1-amino-3-methylbuta-1,3-diene for a combination of prenal with 0.1 equiv. of the corresponding chiral amine results in the products of much lower enantiomeric purity.
- Serebryakov,Nigmatov,Shcherbakov,Struchkova
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- Optically active 3-(1-(alkylamino))alkyl pyrrolidines
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This invention relates to processes for the synthesis of various optically active amino pyrrolidinyl stereoisomers, or enantiomers, that may be attached to quinolonecarboxylic acids or naphthyridones. Processes and essential intermediates are disclosed an
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- New asymmetric synthesis of (-)-esermethole
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A new synthesis of (-)-esermethole, based on the asymmetric alkylation at C(3) of racemic 1,3-dimethyl-5-methoxyoxindole (3), is described. The chloroacetyl derivatives of (-)-menthol and (S)-N-methyl-(1-phenylethyl) amine were chosen as chiral alkylating agents and used under different reaction conditions (temperature, solvent and base). In particular, the latter reacted with 3 in toluene at 10°C, in the presence of t-butyllitium, giving (3S,1'S)-N-methyl-N-(1'-phenylethyl)-1,3-dimethyl-5-methoxyoxindol-3-i lacetamide (10) with a 63% d.e.. This intermediate was easily separated from the undesired minor (3R,1'S) diastereomer (11) and converted to (-)-esermethole (99.6% e.e.) in two steps.
- Pallavicini,Valoti,Villa,Resta
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p. 363 - 370
(2007/10/02)
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- Asymmetric Catalysis, 77. - New Optically Active Pyrazole Derivatives for Enantioselective Catalysis
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Starting from the amines 3-6 and the dipyrazolopyrazinedione 2, the optically active (pyrazolylmethyl)amines 11-14 have been synthesized.Furthermore, the preparation of the (+)-camphor-derived optically active pyrazole 17 is described.Pyrazoles 11-13 and 17 are introduced as chiral building blocks into the 2-(1-pyrazolyl)pyridines 30-33.The optically active compounds 23-25 are formed from 2-pyridine and 2,6-bispyridine, respectively, and (+)-3-(bromomethyl)pinane.The pyrazole derivatives 27-29 contain (+)-(1-phenylethyl)hydrazine as the optically active component.Key Words: Pyrazoles, optically active / Pyridines, 2--, 2,6-bis-, 2-(1-pyrazolyl)-
- Brunner, Henri,Scheck, Thomas
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p. 701 - 710
(2007/10/02)
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- Evidence for an Intramolecular, Stepwise Reaction Pathway for PEP Phosphomutase Catalyzed P-C Bond Formation
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The Tetrahymena pyriformis enzyme, phosphoenolpyruvate phosphomutase, catalyzes the rearrangement of phosphoenolpyruvate to the P-C bond containing metabolite, phosphonopyruvate.To distinguish between an intra- and intermolecular reaction pathway for this process an equimolar mixture of 18O,C(2)-18O>thiophosphonopyruvate and (all 16O) thiophosphonopyruvate was reacted with the phosphonomutase, and the resulting products were analyzed by 31P NMR.The absence of the cross-over product 18O>thiophosphonoenolpyruvate in the product mixture was interpreted as evidence for an intramolecular reaction pathway.To distinguish between a concerted and stepwise intramolecular reaction pathway the pure enantiomers of the chiral substrate 18O>-thiophosphonopyruvate were prepared and the stereochemicalb course of their conversion to chiral 18O>thiophosphoenolpyruvate was determined.The assignments of the phosphorous configurations in the 18O>thiophosphonopyruvate enantiomers reported earlier (McQueney, M.S.; Lee, S.-l.; Bowman, E.; Mariano, P.S.; Dunaway- Mariano, D.J.Am.Chem.Soc. 1989, 111, 6885-6887) were revised according to the finding that introduction of the 18O label into the thiophosphonopyruvate precursor occurs with retention rather than with (the previously assumed) inversion of configuration.On the basis the observed conversion of (Sp)-18O>thiophosphonopyruvate to (Sp)-18O>thiophosphonoenolpyruvate and (Rp)-18O>thiophosphonopyruvate to (Rp)-18O>thiophosphonoenolpyruvate, it was concluded that the PEP phosphomutase reaction proceeds with retention of the phosphorus configuration and therefore by a stepwise mechanism.Lastly, the similar reactivity of the oxo- and thio-substituted phosphonopyruvate substrates (i.e., nearly equal Vmax) was interpreted to suggest that nucleophilic addition to the phosphorus atom is not rate limiting among the reaction steps.
- McQueney, Michael S.,Lee, Sheng-lian,Swartz, William H.,Ammon, Herman L.,Mariano, Patrick S.,Dunaway-Mariano, Debra
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p. 7121 - 7130
(2007/10/02)
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- CD OF PRIMARY AMINES AND 1- OR 3-SUBSTITUTED TETRAHYDROISOQUINOLINES IN PRESENCE OF
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The syntheses of (S)-(-)-1,2-dimethyl-1,2,3,4-tetrahydroisoquinoline (IX) and S-(+)-2,3-dimethyl-1,2,3,4-tetrahydroisoquinoline (XVI) in optically pure form and with known absolute configuration is described.The CD and NMR spectra of these compounds and of most of their intermediates are given, and from these data could be deduced, that the N-methyl groups of the two bases IX and XVI adopt different conformations in solution, but the same (viz. axial) in their complexes with .
- Diener, Wolfgang,Frelek, Jadwiga,Snatzke, Guenther
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p. 954 - 965
(2007/10/02)
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- Stereoselective α-Methylation of N-Methyl Benzylamine via a Combination of Chromium Tricarbonyl and Chiral Formamidine Methodologies.
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Whereas carbanions of formamidines derived from N-methyl benzylamine and L-valinol or L-leucinol undergo electrophilic benzylic methylation with poor stereoselectivities (d.e. 17-26percent), enhanced stereoselectivities (d.e. 74-84percent) are observed for the corresponding chromium tricarbonyl complexes.
- Albert, Joan,Davies, Stephen G.
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p. 5945 - 5948
(2007/10/02)
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- DERIVATIVES OF OPTICALLY ACTIVE (1-PHENYLETHYL)AMINE IN COMPLEXES WITH LITHIUM ALUMINUM HYDRIDE FOR THE ASYMMETRIC REDUCTION OF A CARBONYL GROUP
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(R)-1-Phenylethanol is formed preferentially in the reduction of acetophenone by the complexes of lithium aluminum hydride with (-)-(2-hydroxyethyl)(1-phenylethyl)amine and (-)-methyl(2-hydroxyethyl)(1-phenylmethyl)amine.
- Potapov, V. M.,Dem'yanovich, V. M.,Maleev, V. I.
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p. 1606 - 1609
(2007/10/02)
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- Optically active imidazolidin-2-one derivatives
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A novel optically active cis-4,5-disubstituted imidazolidin-2-one derivative of the formula: STR1 wherein R1 is a C1 -C4 alkyl group or benzyl and R2 is a chiral aralkyl group optionally having at least one of C1 -C4 alkyl, C1 -C4 alkoxy and hydroxyl groups is produced asymmetrically by the reaction of 1,3-dibenzyl-cis-4,5-dicarboxy-imidazolidin-2-one or its anhydride with an optically active secondary amine of the formula: STR2 wherein R1 and R2 are each as defined above and is transformed into the lactone of 1,3-dibenzyl-cis-4-carboxy-5-hydroxymethyl-imidazolidin-2-one, which is a key intermediate in the synthesis of d-biotin.
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- STEREOCHEMICAL INVESTIGATIONS. LII. CHIRAL AMIDES OF o-HYDROXY- AND o-METHOXY-SUBSTITUTED BENZOIC ACIDS
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A number of o-hydroxy- and o-methoxybenzamides have been obtained from (-)-α-phenylamine, (+)-α-benzylethylamine, and (-)-1,2-diphenylethylamine, and their UV, IR, PMR, and CD spectra have been studied.The chiral optical properties of these amides are determined primarily by the nature of the cyclic structure which can form as a result of intramolecular hydrogen bonding.
- Solov'eva, L. D.,Dem'yanovich, V. M.,Potapov, V. M.
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p. 1099 - 1105
(2007/10/02)
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