- Synthesis method of silodosin
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The invention discloses a synthesis method of silodosin. The synthesis method comprises the following steps of: sequentially performing amino protection, bromination and deprotection on indoline serving as a raw material; carrying out an SN2 reaction to o
- -
-
Paragraph 0068; 0086-0088
(2021/07/24)
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- 1,3,2-Diazaphospholenes Catalyze the Conjugate Reduction of Substituted Acrylic Acids
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The potent nucleophilicity and remarkably low basicity of 1,3,2-diazaphospholenes (DAPs) is exploited in a catalytic, metal-free 1,4-reduction of free α,β-unsaturated carboxylic acids. Notably, the reduction occurs without a prior deprotonation of the carboxylic acid moiety and hence does not consume an additional hydride equivalent. This highlights the excellent nucleophilic character and low basicity of DAP-hydrides. Functional groups such as Cbz group or alkyl halides which can be problematic with classical transition-metal catalysts are well tolerated in the DAP-catalyzed process. Moreover, the transformation is characterized by a low catalyst loading, mild reaction conditions at ambient temperature as well as fast reaction times and high yields. The proof-of-principle for a catalytic enantioselective version is described.
- Reed, John H.,Cramer, Nicolai
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p. 4262 - 4266
(2020/07/13)
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- A palladium nanoparticle-nanomicelle combination for the stereo-selective semihydrogenation of alkynes in water at room temperature
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The addition of NaBH4 to Pd(OAc) 2 in water containing nanomicelles leads to the generation of H2 and Pd nanoparticles. Subsequent reduction of disubstituted alkynes affords Z-alkenes in high yields. These reactions are general, take place in water at ambient temperatures, and offer recycling of the aqueous reaction mixture along with low overall E Factors.
- Slack, Eric D.,Gabriel, Christopher M.,Lipshutz, Bruce H.
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supporting information
p. 14051 - 14054
(2015/02/19)
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- Regioselective double Boekelheide reaction: First synthesis of 3,6-dialkylpyrazine-2,5-dicarboxaldehydes from dl-alanine
-
Pyrazine-2,5-dicarboxaldehyde was synthesized on a multi-gram scale by MnO2 oxidation of 2,5-bis(hydroxymethyl)pyrazine, which in turn was obtained from 2,5-dimethylpyrazine employing double Boekelheide reaction as a key step as reported previously. This reaction was subsequently utilized in a regioselective fashion as a key step to synthesize efficiently, for the first time, 3,6-di(long-chain)alkylpyrazine-2,5-dicarboxaldehydes starting from dl-alanine. These monomers are certain to have importance as electron deficient and chemically versatile components for new materials development.
- Das, Sajal Kumar,Frey, Joseph
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scheme or table
p. 3869 - 3872
(2012/08/14)
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- Papain-Specific Activating Esters in Aqueous Dipeptide Synthesis
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Enzymatic peptide synthesis has the potential to be a viable alternative for chemical peptide synthesis. Because of the increasing commercial interest in peptides, new and improved enzymatic synthesis methods are desirable. In recently developed enzymatic strategies such as substrate mimetic approaches and enzyme-specific activation, use of the guanidinophenyl ester (OGp) group has been shown to suffer from some drawbacks. OGp esters are sensitive to spontaneous chemical hydrolysis and the group is expensive to synthesize and therefore not suitable for large-scale applications. On the basis of earlier computational studies, we hypothesized that OGp might be replaceable by simpler ester groups to make the enzyme-specific activation approach to peptide bond formation more accessible. To this end, a set of potential activating esters (Z-Gly-Act) was designed, synthesized, and evaluated. Both the benzyl (OBn) and the dimethylaminophenyl (ODmap) esters gave promising results. For these esters, the scope of a model dipeptide synthesis reaction under aqueous conditions was investigated by varying the amino acid donor. The results were compared with those obtained from a previous study of Z-XAA-OGp esters. Computational docking analysis of the set of esters was performed in order to provide insight into the differences in the reactivities of all the potential activating esters. Finally, selected ODmap- and OBn-activated amino acids were applied in the synthesis of two biologically active dipeptides on preparative scales.
- de Beer, Roseri J.A.C.,Zarzycka, Barbara,Mariman, Michiel,Amatdjais-Groenen, Helene I.V.,Mulders, Marc J.,Quaedflieg, Peter J.L.M.,van Delft, Floris L.,Nabuurs, Sander B.,Rutjes, Floris P.J.T.
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scheme or table
p. 1319 - 1326
(2012/08/28)
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- Papain-catalyzed peptide bond formation: Enzyme-specific activation with guanidinophenyl esters
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The substrate mimetics approach is a versatile method for small-scale enzymatic peptide-bond synthesis in aqueous systems. The protease-recognized amino acid side chain is incorporated in an ester leaving group, the substrate mimetic. This shift of the specific moiety enables the acceptance of amino acids and peptide sequences that are normally not recognized by the enzyme. The guanidinophenyl group (OGp), a known substrate mimetic for the serine proteases trypsin and chymotrypsin, has now been applied for the first time in combination with papain, a cheap and commercially available cysteine protease. To provide insight in the binding mode of various Z-XAA-OGp esters, computational docking studies were performed. The results strongly point at enzyme-specific activation of the OGp esters in papain through a novel mode of action, rather than their functioning as mimetics. Furthermore, the scope of a model dipeptide synthesis was investigated with respect to both the amino acid donor and the nucleophile. Molecular dynamics simulations were carried out to prioritize 22 natural and unnatural amino acid donors for synthesis. Experimental results correlate well with the predicted ranking and show that nearly all amino acids are accepted by papain.
- de Beer, Roseri J.A.C.,Zarzycka, Barbara,Amatdjais-Groenen, Helene I.V.,Jans, Sander C.B.,Nuijens, Timo,Quaedflieg, Peter J.L.M.,van Delft, Floris L.,Nabuurs, Sander B.,Rutjes, Floris P.J.T.
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experimental part
p. 2201 - 2207
(2012/05/05)
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- ALKYL-SUBSTITUTED 3' COMPOUNDS HAVING 5-HT6 RECEPTOR AFFINITY
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The present disclosure provides compounds having affinity for the 5-HT6 receptor which are of the formula (I): wherein R1, R2, Ar, m and n are as defined herein. The disclosure also relates to methods of preparing such compounds, compositions containing such compounds, and methods of use thereof.
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-
Page/Page column 35-36
(2010/02/17)
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- COMPOSITIONS AND METHODS FOR CYCLOFRUCTANS AS SEPARATION AGENTS
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The present invention relates to derivatized cyclofructan compounds, compositions comprising derivatized cyclofructan compounds, and methods of using compositions comprising derivatized cyclofructan compounds for chromatographic separations of chemical species, including enantiomers. Said compositions may comprise a solid support and/or polymers comprising derivatized cyclofructan compounds.
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Page/Page column 45-49; 51
(2010/12/31)
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- Development of new HPLC chiral stationary phases based on native and derivatized cyclofructans
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An unusual class of chiral selectors, cyclofructans, is introduced for the first time as bonded chiral stationary phases. Compared to native cyclofructans (CFs), which have rather limited capabilities as chiral selectors, aliphatic-and aromatic-functionalized CF6s possess unique and very different enantiomeric selectivities. Indeed, they are shown to separate a very broad range of racemic compounds. In particular, aliphatic-derivatized CF6s with a low substitution degree baseline separate all tested chiral primary amines. It appears that partial derivatization on the CF6 molecule disrupts the molecular internal hydrogen bonding, thereby making the core of the molecule more accessible. In contrast, highly aromaticfunctionalized CF6 stationary phases lose most of the enantioselective capabilities toward primary amines, however they gain broad selectivity for most other types of analytes. This class of stationary phases also demonstrates high "loadability" and therefore has great potential for preparative separations. The variations in enantiomeric selectivity often can be correlated with distinct structural features of the selector. The separations occur predominantly in the presence of organic solvents.
- Sun, Ping,Wang, Chunlei,Breitbach, Zachary S.,Zhang, Ying,Armstrong, Daniel W.
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experimental part
p. 10215 - 10226
(2010/05/01)
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- Resolution of non-proteinogenic amino acids via microbial lipase-catalyzed enantioselective transesterification
-
A number of non-proteinogenic amino acids bearing aliphatic side chains were resolved with moderate to good enantioselectivities (E = 15-42) through the Burkholderia cepacia lipase-catalyzed enantioselective transesterification of the 2,2,2-trifluoroethyl esters of their N-benzyloxycarbonyl derivatives with methanol as a nucleophile in diisopropyl ether.
- Miyazawa, Toshifumi,Mio, Motoe,Watanabe, Yuko,Yamada, Takashi
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p. 219 - 224
(2008/09/20)
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- Synthesis and utilization of chiral α-methylated α-amino acids with a carboxyalkyl side chain in the design of novel Grb2-SH2 peptide inhibitors free of phosphotyrosine
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The growth factor receptor-bound protein 2 (Grb2) is an SH2 domain-containing docking module that represents an attractive target for anticancer therapeutic intervention. To improve the potency and bioavailability of the Grb2-SH2 inhibitors, the chiral α-methyl-α-carboxyalkyl amino acid [(α-Me)Aa] was designed to cover dual structural and functional features separately contributed by 1-aminocyclohexanecarboxylic acid (Ac6c) and α-aminoadipic acid (Adi) in position Y + 1. The enantiopure L(or D)-(α-Me)Aa bearing various chain length carboxylalkyl side chain was conveniently synthesized by an optimized oxazolidinone methodology. The incorporation of (S)-(α-Me)Aa into the non-pTyr-containing peptide framework with a 5-amino acid sequence binding motif of X-2-Leu- (3′-substituted-Tyr)0-X+1-Asn really improved the inhibitory activity, affording potent (R)-sulfoxide-bridged cyclic and an open-chain series of pentapeptide inhibitors of Grb2-SH2 domain (IC50 = 1.1-5.8 μM). More significantly, these (α-Me)Aa incorporated peptide inhibitors showed excellent activities in inhibiting the growth of erbB2-dependent MDA-MB-453 tumor cell lines with low micromolar IC50 values, owing to the reduced peptidic nature and absence of pTyr or pTyr mimetics.
- Long, Ya-Qiu,Xue, Ting,Song, Yan-Li,Liu, Zu-Long,Huang, Shao-Xu,Yu, Qiang
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experimental part
p. 6371 - 6380
(2009/10/17)
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- A Stereoselective entry into functionalized 1,2-diamines by zinc-mediated homologation of α-aminoacids
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A general, stereoselective synthsis of 4,5-disubstituted imidazolidines-2-ones from α-aminoacids has been developed: the key steps are a Biaise reaction of bromoacetate on α-aminonitriles and further reduction. Although reduction with sodium cyanoborohydride afforded a mixture of cis and trans isomers 6a-e with moderate to good stereoselectivity, reduction with sodium in liquid ammonia gave the trans isomers 8a-e with complete stereoselectivity. Acidic hydrolysis of the urea gave 4-amino-pyrrolidinones, which can be precursors to β,γ-diaminoacids or 3-aminopyrrolidines.
- Hoang, Cam Thuy,Alezra, Valerie,Guillot, Regis,Kouklovsky, Cyrille
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p. 2521 - 2524
(2008/02/05)
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- Diastereoselective cationic tandem cyclizations to N-heterocyclic scaffolds: Total synthesis of (-)-dysibetaine PP
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Herein, we report a short and diastereoselective synthesis of the natural product (-)-dysibetaine PP. The key step in the synthetic sequence is a novel highly diastereoselective tandem-cyclization reaction of an enantiomerically pure dipeptide. This cyclization methodology is applied in the synthesis of a broader range of N-heterocyclic scaffolds.
- IJzendoorn, Denis R.,Botman, Peter N. M.,Blaauw, Richard H.
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p. 239 - 242
(2007/10/03)
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- Resolution of non-protein amino acids via Carica papaya lipase-catalyzed enantioselective transesterification
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Carica papaya lipase-catalyzed transesterification of the 2,2,2-trifluoroethyl esters of N-benzyloxycarbonylated dl-amino acids carrying aliphatic side chains proceeded smoothly and, in almost all the cases, enantiospecifically (E = >200), affording the l-methyl esters and leaving the d-trifluoroethyl esters intact.
- Miyazawa, Toshifumi,Onishi, Kazuki,Murashima, Takashi,Yamada, Takashi,Tsai, Shau-Wei
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p. 2569 - 2573
(2007/10/03)
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- A cyclic hexapeptide comprising alternating α-aminoxy and α-amino acids is a selective chloride ion receptor
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In nonpolar solvents, the cyclic hexapeptide 2, which comprises alternating D-α-amino and D-α-aminoxy acids, adopts a C3-symmetric conformation with alternating eight (N-O turns)- and seven (γ turns)-membered-ring hydrogen bonds. A series of anion-binding studies has suggested that 2 can function as an effective anion receptor that not only displays a high selectivity for chloride ions, but also the capability to extract chloride ions from aqueous solutions into organic phases.
- Yang, Dan,Li, Xiang,Sha, Yao,Wu, Yun-Dong
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p. 3005 - 3009
(2007/10/03)
-
- Synthesis and pharmacological evaluation of glycine-modified analogues of the neuroprotective agent glycyl-L-prolyl-L-glutamic acid (GPE)
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The synthesis of 10 G*PE analogues, wherein the glycine residue has been modified, is described by coupling readily accessible dibenzyl-l-prolyl-l- glutamate 2 with various analogues of glycine. Pharmacological evaluation of the novel compounds was undertaken to further understand the role of the glycine residue on the observed neuroprotective properties of the endogenous tripeptide GPE.
- Lai, Michelle Y.H.,Brimble, Margaret A.,Callis, David J.,Harris, Paul W.R.,Levi, Mark S.,Sieg, Frank
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p. 533 - 548
(2007/10/03)
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- The preparation and alkylation of a butanedione-derived chiral glycine equivalent and its use for the synthesis of α-amino acids and α,α-disubstituted amino acids
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A benzyloxycarbonyl protected glycine equivalent 2 has been prepared in enantiopure form and has been used in the synthesis of both α-substituted amino acids and α,α-disubstituted amino acids. The process involved deprotonation to form the corresponding enolates which underwent stereoselective alkylation with various electrophiles and upon hydrolysis gave the corresponding amino acid derivatives as enantiomerically pure products.
- Harding, Christopher I.,Dixon, Darren J.,Ley, Steven V.
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p. 7679 - 7692
(2007/10/03)
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- A 2,3-butanedione protected chiral glycine equivalent--a new building block for the stereoselective synthesis of enantiopure N-protected alpha-amino acids.
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A new chiral glycine equivalent 7 has been synthesised from glycidol using a chiral memory protocol, and its use in the synthesis of N-Z protected alpha-amino acids was demonstrated in a series of diasteroselective lithium enolate alkylation reactions and subsequent acid hydrolyses.
- Dixon, Darren J,Harding, Christopher I,Ley, Steven V,Tilbrook, D Matthew G
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p. 468 - 469
(2007/10/03)
-
- Flash vacuum pyrolysis of stabilised phosphorus ylides. Part 17. Preparation of aliphatic amino acid derived γ-alkoxycarbonyl-amino-β-oxo ylides and pyrolysis to give α,β-acetylenic γ-amino acid and GABA analogues
-
A series of eleven α-aminoacyl stabilised phosphorus ylides 9-19 have been prepared by condensation of N-alkoxycarbonyl protected amino acids with Ph3P = CHCO2Et using a carbodiimide peptide coupling reagent. Upon flash vacuum pyrolysis at 600 °C, these undergo extrusion of Ph3PO to give the corresponding α,β-acetylenic γ-amino esters 21-29, 33 and 34 in moderate yield. In two cases the terminal alkynes 30 and 31 are also formed. The β-aminoacyl ylide 20 from β-alanine similarly gives the α,β-acetylenic δ-amino ester 35 upon pyrolysis. Regioselective addition of HBr to the triple bond of one acetylenic ester 25 was observed giving a mixture of E and Z α-bromoacrylates 36. Hydrogenation of the N-Cbz acetylenic esters 21-23 and 33 results in N-deprotection and hydrogenation of the triple bond to afford the chiral GABA analogues 37-40 in 70 ->95% ee as determined by 19F NMR of their Mosher amides. Fully assigned 13C NMR spectra of all the ylides and acetylenic ester derivatives are presented.
- Aitken, R. Alan,Karodia, Nazira,Massil, Tracy,Young, Robert J.
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p. 533 - 541
(2007/10/03)
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- Cyclodextrin-mediated deacylation of amino acid esters with marked stereoselectivity.
-
With respect to the hydrolysis (deacylation) of Z-D(L)-amino acid esters (N-(benzyloxycarbonyl)-D(L)-amino acid p-nitrophenyl esters) mediated by alpha-, beta- and gamma-cyclodextrins (CyDs), a remarkably high enantioselectivity (L/D=9.0) was observed for the deacylation of Ala substrate with gamma-CyD. The kinetic results on the basis of the Michaelis-Menten principle indicate that the enantioselectivity should be mainly originated in the deacylation process of substrates following the formation of gamma-CyD-substrate (1 : 1) complexes. The computer modeling (molecular mechanics) studies on the inclusion complexes are also described.
- Goto, Koichi,Nakashima, Kentaro,Tanoue, Osamu,Nukushina, Satoshi,Toudo, Isao,Imamura, Chikara,Ihara, Yasuji,Matsumoto, Yoko,Ueoka, Ryuichi
-
p. 1283 - 1285
(2007/10/03)
-
- Indium metal as a reducing agent in organic synthesis
-
The low first ionisation potential (5.8 eV) of indium coupled with its stability towards air and water, suggest that this metallic element should be a useful reducing agent for organic substrates. The use of indium metal for the reduction of C=N bonds in imines, the heterocyclic ring in benzo-fused nitrogen heterocycles, of oximes, nitro compounds and conjugated alkenes and the removal of 4-nitrobenzyl protecting groups is described. Thus the heterocyclic ring in quinolines, isoquinolines and quinoxalines is selectively reduced using indium metal in aqueous ethanolic ammonium chloride. Treatment of a range of aromatic nitro compounds under similar conditions results in selective reduction of the nitro groups; ester, nitrile, amide and halide substituents are unaffected. Likewise indium in aqueous ethanolic ammonium chloride is an effective method for the deprotection of 4-nitrobenzyl ethers and esters. Indium is also an effective reducing agent under non-aqueous conditions and α-oximino carbonyl compounds can be selectively reduced to the corresponding N-protected amine with indium powder, acetic acid in THF in the presence of acetic anhydride or di-tert-butyl dicarbonate. Conjugated alkenes are also reduced by indium in THF-acetic acid.
- Pitts,Harrison,Moody
-
p. 955 - 977
(2007/10/03)
-
- A novel concept in combinatorial chemistry in solution with the advantages of solid-phase synthesis: Formation of N-betaines by multicomponent domino reactions
-
Advantages of solid-phase and liquid-phase synthesis are combined in a new concept of combinatorial chemistry: a domino sequence comprising Knoevenagel and hetero-Diels-Alder reactions, with subsequent hydrogenation starting from protected aminoaldehydes, 1.3-dicarbonyl compounds, and enol ethers leads to N-heterocycles of high diversity with a betaine structure, which are isolated in highly pure form by precipitation with diethyl ether (see scheme), Cbz = benzylocycarbonyl, Bn = benzyl.
- Tietze, Lutz F.
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p. 903 - 905
(2007/10/03)
-
- Simple and efficient preparation of (R)- and (S)-enantiomers of α-carbon deuterium-labelled α-amino acids
-
A procedure for the synthesis of (R)- and (S)-enantiomers of α-carbon deuterium-labelled α-amino acids, exemplified for (R)- and (S)-[2-2H1]-Leu is described. Starting from the respective (S)- or (R)-enantiomer or from the racemic mixture of an α-amino acid the selective proton exchange at the α-carbon is carried out by racemization via a Schiff base in monodeuterated acetic acid as solvent which serves as deuterium source. After N-protection the racemic mixture is liquid chromatographically separated into the individual (R)- and (S)-enantiomers on preparative scale employing a chiral anion exchanger based on carbamoylated quinine as chiral selector. After deprotection the enantiomerically pure products can be obtained in good yields.
- Mitulovi, Goran,Laemmerhofer, Michael,Maier,Lindner, Wolfgang
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p. 449 - 461
(2007/10/03)
-
- An investigation of antibody acyl hydrolysis catalysis using a large set of related haptens
-
An aspect of catalytic antibody research that receives little attention in the literature involves hapten systems that fail to elicit antibody catalysts despite a high affinity immune response and hapten designs that resemble those known to elicit catalysts. We have investigated a series of 12 phosphate and phosphonate haptens in a total of three animal systems. Dramatic and reproducible differences were observed in the catalytic activities of polyclonal antibodies elicited by the different haptens. A phosphate hapten with a phenyl ring on the side of the hapten opposite the linker elicited reproducibly high levels of polyclonal antibody catalytic activity. The other 11 haptens, most with benzyl groups on the side of the hapten opposite the linker, elicited immune responses in which catalytic activity was significantly weaker in terms of the level of observed catalytic activity, as well as frequency of elicited catalysts. Our results indicate that subtle features of transition state analogue hapten structure can have a dramatic and reproducible influence over the catalytic activity of elicited antibodies in related haptens. Whatever the explanation, subtle changes in mechanistic features due to altered leaving group ability/location or overall hapten flexibility, the comprehensive data presented here indicate that phenyl or 4-nitrophenyl leaving groups located opposite the hapten linker are to be preferred in order to elicit highly active antibody catalysts for acyl hydrolysis reactions. (C) 2000 Elsevier Science Ltd.
- Odenbaugh, Amy L.,Helms, Eric D.,Iverson, Brent L.
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p. 413 - 426
(2007/10/03)
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- Indium as a reducing agent: Deprotection of 4-nitrobenzyl ethers and esters
-
Indium in aqueous ethanolic ammonium chloride is an effective method for the deprotection of 4-nitrobenzyl ethers and esters.
- Moody, Christopher J.,Pitts, Michael R.
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p. 1575 - 1576
(2007/10/03)
-
- Chiral oxime ethers in asymmetric synthesis. 3. Asymmetric synthesis of (R)-N-protected α-amino acids by the addition of organometallic reagents to the ROPHy oxime of cinnamaldehyde
-
A new asymmetric synthesis of α-amino acids is described in which the key step is the diastereoselective addition of organometallic reagents to (R)-O-(1-phenylbutyl)cinnamaldoxime 5 to give hydroxylamines 6. Subsequent reductive cleavage of the N-O bond in the hydroxylamine 6 followed by N- protection gave the carbamates 7, which upon oxidation with ruthenium(III) chloride/periodate gave the N-protected amino acids 8. The method was also adapted to the synthesis of a quaternary amino acid 15 from the ketoxime ether 9.
- Moody, Christopher J.,Gallagher, Peter T.,Lightfoot, Andrew P.,Slawin, Alexandra M. Z.
-
p. 4419 - 4425
(2007/10/03)
-
- Remarkable effects of donor esters on the α-chymotrypsin-catalyzed couplings of inherently poor amino acid substrates
-
The extremely low efficiency during the α-chymotrypsin-catalyzed coupling of an inherently poor amino acid substrate, e.g., alanine, using the methyl ester as an acyl donor was significantly improved using esters such as the 2,2,2-trifluoroethyl or carbamoylmethyl ester. The ameliorating effect of the latter ester was especially significant.
- Miyazawa, Toshifumi,Tanaka, Kayoko,Ensatsu, Eiichi,Yanagihara, Ryoji,Yamada, Takashi
-
p. 997 - 1000
(2007/10/03)
-
- New facile alkoxycarbonylating agent, alkyl pyrazole-1-carboxylates. The preparation and the utilities
-
Alkyl pyrazole-1-carboxylates (2), which were readily prepared from alkyl chloroformate or carbazate in good yields, were provided as the new facile alkoxycarbonylating agents toward the Grignard reagents for the synthesis of one carbon higher carboxylic esters. Also amines were alkoxycarbonylated by 2 to produce the corresponding urethanes even in an aqueous medium. Benzyl 3,5-dimethylpyrazole-1-carboxylate (2d) could be utilized for the Cbz-protection of amino acids and esters in good yield without any racemization.
- Kashima, Choji,Tsuruoka, Shiro,Mizuhara, Saori
-
p. 14679 - 14688
(2007/10/03)
-
- Addition of Organolithiums to the (R)-O-(1-Phenylbutyl)hydroxylamine (ROPHy) Oxime of Cinnamaldehyde. Asymmetric Synthesis of α-Aminoacids
-
A new asymmetric synthesis of α-aminoacids is described in which the key step is the diastereoselective addition of organolithium reagents to (R)-O-(1-phenylbutyl) cinnamaldoxime.
- Moody, Christopher J.,Lightfoot, Andrew P.,Gallagher, Peter T.
-
p. 659 - 660
(2007/10/03)
-
- Relaxing substrate specificity in antibody-catalyzed reactions: Enantioselective hydrolysis of N-Cbz-amino acid esters
-
For a catalytic antibody to be generally useful for organic synthetic chemistry, it must be able to accept a broad range of substrates, yet retain high selectivity. In this work, we propose a hapten design to endow antibody catalysts with two opposing qualities, such as high enantioselectivity and broad substrate specificity. Racemic hapten 2 induced two separate classes of catalytic antibodies to hydrolyze either the L- or D-isomers of N-Cbz-amino acid esters 1. In the kinetic resolution of racemic ester 9, antibodies 7G12 and 3G2 gave 96% ee of L-10 and 94% ee of D-10, respectively. In addition, antibody 7G12 displayed broad substrate specificity, hydrolyzing the L-esters of Ala (1a), Leu (1b), Norleu (1c), Met (1d), Phe (1e), Val (1f), and phenylglycine (1g) with high enantioselectivity. Antibody 3G2 also hydrolyzed the D-isomers of these esters without sacrificing the enantioselectivity. This observation suggests that the use of haptens that fit snugly into the antigen-combining site, and leave the linker moiety outside, is an effective approach for the generation of catalytic antibodies with high selectivity and broad substrate applicability.
- Tanaka, Fujie,Kinoshita, Keiko,Tanimura, Ryuji,Fujii, Ikuo
-
p. 2332 - 2339
(2007/10/03)
-
- Synthesis and Spectroscopic Properties of the Stereoisomeric Esters from L- and D-N-Benzoylalanin and L- and D-N-Benzoylalaninol
-
The synthesis of the stereoisomeric esters of L- and D-N-benzoylalanine and L- and D-N-benzoylalaninol is described. - Keywords: N-Benzoylalaninyl-N'-benzoylalaninate, Stereoisomeric Esters, 1H NMR Data, 13C NMR Data, CD Data
- Huneck, S.,Porzel A.
-
p. 569 - 575
(2007/10/02)
-
- Enzymatic enantioselective ester hydrolysis by carboxylesterase NP
-
The enzymatic hydrolysis of a series of carboxylic esters by carboxylesterase NP has been investigated in order to determine the scope and limitations of this enzyme. 2-Substituted propionates were hydrolyzed with high enantioselectivity when an aromatic moiety was part of the 2-substituent.Enantioselective hydrolysis could be accomplished with several 2-arypropionates, 2-(aryloxy)propionates and N-arylalanine esters.The propionate esters yielded propionic acids as (S) enantiomers, whereas the alanine esters yielded the (R) enantiomers.Without a 2-aryl substituent, the enzymatic hydrolysis of the propionates occurred at a lower rate without acceptable enantioselectivity.In addition to 2-substituted propionates, only a few other esters were hydrolyzed with high enantioselectivity by carboxylesterase NP, such as some prochiral disubstituted malonates. 1-Phenylethylacetate was the only substrate with chirality in the alcohol part of the ester that was found to be hydrolyzed enantioselectively.Carboxylesterase NP proved to be a powerful enzyme for kinetic resolution of propionate esters with an aromatic ring containing a 2-substituent.
- Smeets, J. W. H.,Kieboom, A. P. G.
-
p. 490 - 495
(2007/10/02)
-
- Porcine Pancreatic Lipase Catalyzed Enantioselective Hydrolysis of Esters of N-Protected Unusual Amino Acids
-
Porcine pancreatic lipase catalyzed the highly enantioselective hydrolysis of a kind of α-substituted carboxylic esters, i.e., the 2,2,2-trifluoroethyl esters of the N-benzyloxycarbonyl derivatives of unusual amino acids.
- Miyazawa, Toshifumi,Iwanaga, Hitoshi,Ueji, Shinichi,Yamada,Takashi,Kuwata, Shigeru
-
p. 2219 - 2222
(2007/10/02)
-
- PAPAIN-ASSISTED RESOLUTION OF NATURAL AND XENOBIOTIC α-AMINO ACIDS
-
A new and convenient method for the preparation of pure enantiomers of α-amino acids is described.Industrial papain, catalyzes the synthesis of L-Z-amino acid ethyl esters in ethanolic medium, with good yields.These esters are obtained from DL-Z-amino acids with 100percent optical purity.Unreactive D-Z-amino acids are readily isolated from reaction medium.Physical constants of natural and xenobiotic L-Z-amino acid esters and D-Z-amino acids are described.
- Moriniere, J. L.,Danree, B.,Lemoine, J.,Guy, A.
-
p. 441 - 444
(2007/10/02)
-
- Optical Resolution of Unusual Amino-Acids by Lipase-catalysed Hydrolysis
-
The 2-chloroethyl esters of the N-benzyloxycarbonyl (Z) derivatives of several unusual amino-acids are converted by Aspergillus niger lipase into enantiomerically enriched Z-amino-acids with fairly high optical purities, the L-enantiomers being preferentially hydrolysed.
- Miyazawa, Toshifumi,Takitani, Tadanori,Ueji, Shinichi,Yamada, Takashi,Kuwata, Shigeru
-
p. 1214 - 1216
(2007/10/02)
-
- Direct Optical Resolution of Carboxylic Acids by Chyral HPLC on Tris(3,5-dimethylphenylcarbamate)s of Cellulose and Amylose
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A variety of racemic carboxylic acids have been for the first time directly resolved by normal-phase, high-performance liquid chromatography using a hexane-2-propanol eluting system containing a small amount (ca. 1percent) of a strong carboxylic acid, like formic acid, trichloroacetic acid, and trifluoroacetic acid.
- Okamoto, Yoshio,Aburatani, Ryo,Kaida, Yuriko,Hatada, Koichi
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p. 1125 - 1128
(2007/10/02)
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- Composition containing a penem or carbapenem antibiotic and the use of the same
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Administration of an N-acylated amino acid in association with a penem or carbapenem antibiotic relieves or eliminates the renal problems associated with administration of the antibiotic alone. The amino acid derivative and antibiotic may be formulated together as a composition or administered separately, either simultaneously or sequentially.
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- UTILISATION DES HYDROLASES EN CHIMIE ORGANIQUE: SYNTHESE DE LIAISONS ESTER ET AMIDE CATALYSEE PAR LA PAPAINE INDUSTRIELLE
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The use of hydrolases in organic chemistry: synthesis of amide and ester bonds catalyzed by industrial papain.Industrial papain, which is readily available, catalyzed the synthesis of L-Z-alanine ethyl ester (L-ZAEt) in organic medium, under different conditions, with good yields.L-ZAEt was obtained from DL-Z-alanine with 100 percent optical purity.We studied the effects of pH, the solvent/substrate and papain/substrate ratios and the type of organic solvent added, on the L-ZAEt yield.Unreactive D-ZA was also easily isolated from the aqueous phase with good optical purity.This attractive method has been applied to other N-Z-amino acid esters with the same succes.This procedure has been developed for the preparation of peptides using carboxylic or phosphonic substrates.These peptides have anti-bacterial activity. enzymatic catalysis / papain / chymopapain / stereospecific esterification of carboxylic amino acids / dipeptides / phosphonopeptides / anti-bacterial activity
- Moriniere, Jean-Luc,Danree, Bernard,Guy, Alain
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p. 347 - 358
(2007/10/02)
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- Composition containing a penem or carbapenem antibiotic
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Administration of an N-acylated amino acid in association with a penem or carbapenem antibiotic relieves or eliminates the renal problems associated with administration of the antibiotic alone. The amino acid derivative and antibiotic may be formulated together as a composition or administered separately, either simultaneously or sequentially. The composition may be prepared by simple mixing.
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- Allylic Selenides in Organic Synthesis: New Methods for the Synthesis of Allylic Amines
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Oxidative rearrangement of allylic selenides in the presence of various amine nucleophiles provides synthetic access to a variety of allylic amine derivatives.The stereochemical outcome of these reactions has been investigated, and is consistent with a -sigmatropic rearrangement mechanism.Several D-α-amino acids and racemic β,γ-unsaturated α-amino acids were prepared in this manner.A variant of this process employing an achiral allylic selenide and chiral amide afforded protected allylic amines in low diastereoisomeric excess.
- Shea, Regan G.,Fitzner, Jeffrey N.,Fankhauser, John E.,Spaltenstein, Andreas,Carpino, Philip A.,et al.
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p. 5243 - 5252
(2007/10/02)
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- Method for reductive elimination of protecting groups
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The invention provides a novel and efficient method for the elimination of protecting groups, e.g. benzyloxycarbonyl group, from a protected amino acid, peptide or derivative thereof having at least one functional group protected by a protecting group, e.g. a lower alkyl ester of N-benzyloxycarbonyl-α-L-aspartyl-L-phenylalanine by catalytic hydrogen reduction to produce free amino acid, peptide or derivative thereof. In contrast to the conventional procedures in which the reaction is carried out in a solvent dissolving both the starting compound and the product compound or a solvent dissolving the starting compound but not dissolving the product compound, the inventive method utilizes a binary two-phase reaction medium composed of water and an organic solvent not freely miscible with water such as toluene. The reaction takes place in the organic phase containing the starting compound dissolved and the catalyst dispersed therein whereas the reaction product which is water-soluble is smoothly and successively transferred into the aqueous phase so that advantages are obtained in the unexpectedly high yield of the product as well as in the easiness of handling the reaction mixture after completion of the reaction.
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- STEREOSELECTIVE HYDROLYSIS OF AMINO ACID ESTERS BY MODIFIED POLY(ETHYLENIMINE)S WITH COVALENTLY-LINKED DIPEPTIDE CONTAINING A HISTIDYL RESIDUE
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Stereoselective hydrolyses of chiral substrates were examined in poly(ethylenimine) derivatives with optically active groups.A high stereoselective effect, kL/kD = 3.6, is observed.The effect of the substrate structure influenced both the rate constant and the stereoselective ratio in the hydrolyses by poly(ethylenimine) derivatives.
- Kimura, Yoshiharu,Nango, Mamoru,Ihara, Yasuji,Kuroki, Nobuhiko
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p. 429 - 432
(2007/10/02)
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- STEREOSELECTIVE HYDROLYSIS OF AMINO ACID ESTERS IN MODIFIED LINEAR POLY(ETHYLENIMINE) DOMAINS
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A large rate enhancement and a stereoselective preference are exhibited in the hydrolysis catalysed by N-decanoyl-L-histidine (2a) and a dipeptide containing L-histidyl residue (2b) in the domain of linear poly(ethylimine) derivatives.
- Kimura, Yoshiharu,Kanda, Shinichi,Nango, Mamoru,Ihara, Yasuji,Koga, Joichi,et al.
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p. 433 - 436
(2007/10/02)
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- SYNTHETIC ENZYMES-4. HIGHLY ENANTIOSELECTIVE EPOXIDATION BY MEANS OF POLYAMINOACIDS IN A TRIPHASE SYSTEM: INFLUENCE OF STRUCTURAL VARIATIONS WITHIN THE CATALYSTS.
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The asymmetric epoxidation of chalcone and other electron-poor olefins in a triphase system (water-organic solvent-polyaminoacid) affords optically active oxiranes.The influence of the molecular structure of catalysts and of their secondary conformation on the enantioselectivity of the reaction has also been examined.
- Colonna, Stefano,Molinari, Henriette,Banfi, Stefano,Julia, Sebastian,Masana, Jaume,Alvarez, Angel
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p. 1635 - 1642
(2007/10/02)
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- Stereoselective Micellar Catalysis. Part 3. Co-operative Effects of N-Decanoyl-L-histidine for the Hydrolysis of Enantiomeric Substrates
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The catalytic activities of N-decanoyl-L-histidine (Ia) and its methyl ester (Ib) toward the hydrolyses of enantiomeric substrates (II) have been investigated in the presence of cetyltrimethylammonium bromide micelles.The comparison of catalytic effects (both the rate constants and stereoselectivities) of (Ia) and (Ib) strongly suggests that carboxylate ion of (Ia) intramolecularly enhances the reactivity of the imidazole group.The presence of co-operative effects is also supported by the pH-rate profile and by the thermodynamic parameters of the reaction.
- Ihara, Yasuji,Hosako, Reiko,Nango, Mamoru,Kuroki, Nobuhiko
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- Stereoselective micellar catalysis. Reactions of amino-acid ester derivatives with N-acyl-L-histidine in micelles
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Mixed micelles of the N-acyl-L-histidines (I) and cetyltrimethylammonium bromide (CTABr) are effective stereoselective catalysts for cleavage of the enantiomeric amino-acid ester derivatives (II). The rate enhancements and stereoselective effects depend on the hydrophobicity of (I) in micelles, and an increase in the chain length of the acyl part of (I) increases both the reaction rates and the enantiomer rate ratio. Mixed micelles with anionic and nonionic surfactants are relatively less effective stereoselective catalysts. Kinetic analysis indicates that the stereoselectivity in mixed micelles is mainly determined by catalytic acyl transfer to the optically active imidazole group of (I).
- Ihara, Yasuji
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p. 1483 - 1487
(2007/10/02)
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- Hexapeptides and methods for their production
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New hexapeptides having the formula X-Ser(benzyl)-Tyr(benzyl)-Ala-Leu-Arg-Pro-Y wherein X is t-butoxycarbonyl or benzyloxycarbonyl and Y is lower alkoxy, amino, lower alkylamino or di(lower alkyl)amino.
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