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Amino Acid Esters (amino + acid_ester)
Selected AbstractsChemInform Abstract: Synthesis of Chiral Tetraaminophosphonium Chlorides from N-Boc ,-Amino Acid Esters.CHEMINFORM, Issue 18 2009Daisuke Uraguchi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Synthesis and Selected Transformations of 1H-Imidazole 3-Oxides Derived from Amino Acid Esters.CHEMINFORM, Issue 9 2009Marcin Jasinski Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Intermolecular One-Pot Cyclization of Formyl-Pyrroles of Amino Acid Esters with Norephedrine: Stereoselective Routes to New Tricyclic Pyrrole,Pyrazine,Oxazole Fused Structures.CHEMINFORM, Issue 11 2007Ayhan S. Demir Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Novel Approach to Arylhydrazones, the Precursor for Fischer Indole Synthesis, via Diazo Esters Derived from ,-Amino Acid Esters.CHEMINFORM, Issue 17 2006Eiko Yasui Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Synthesis of Cyclic ,-Amino Acid Esters from Methionine, Allylglycine, and Serine.CHEMINFORM, Issue 37 2004James Gardiner Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Palladium-Catalyzed Intramolecular ,-Arylation of ,-Amino Acid Esters.CHEMINFORM, Issue 26 2002Oliver Gaertzen Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: A New Receptor Molecule for Lysine and Histidine in Water: Strong Binding of Basic Amino Acid Esters by a Macrocyclic Host.CHEMINFORM, Issue 37 2001Thomas Grawe Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Novel Synthesis of Cyclic ,-Amino Acid Esters via Ene Reaction and Ruthenium-Catalyzed Ring Rearrangement.CHEMINFORM, Issue 33 2001Sergey N. Osipov Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Synthesis of 1,3-Thiazolidines from Aromatic Thioketones and N-Benzylidene ,-Amino Acid Esters via 1,3-Dipolar Cycloaddition of Azomethine Ylides.CHEMINFORM, Issue 26 2001Andreas Gebert Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Enantio- and Diastereoselective Hydrogenation via Dynamic Kinetic Resolution by a Cationic Iridium Complex in the Synthesis of ,-Hydroxy-,-amino Acid Esters.CHEMINFORM, Issue 3 2007Kazuishi Makino Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Co-electrospun composite nanofibers of blends of poly[(amino acid ester)phosphazene] and gelatinPOLYMER INTERNATIONAL, Issue 5 2010Yi-Jun Lin Abstract Electrospinning is known as a simple and effective fabrication method to produce polymeric nanofibers suitable for biomedical applications. Many synthesized and natural polymers have been electrospun and reported in the literature; however, there is little information on the electrospinning of poly[(amino acid ester)phosphazene] and its blends with gelatin. Composite nanofibers were made by co-dissolving poly[(alaninoethyl ester)0.67(glycinoethyl ester)0.33phosphazene] (PAGP) and gelatin in trifluoroethanol and co-electrospinning. The co-electrospun composite nanofibers from different mixing ratios (0, 10, 30, 50, 70 and 90 wt%) of gelatin to PAGP consisted of nanoscale fibers with a mean diameter ranging from approximately 300 nm to 1 µm. An increase in gelatin in the solution resulted in an increase of average fiber diameter. Transmission electron microscopy and energy dispersive X-ray spectrometry measurements showed that gelatin core/PAGP shell nanofibers were formed when the content of gelatin in the hybrid was below 50 wt%, but homogeneous PAGP/gelatin composite nanofibers were obtained as the mixing ratios of gelatin to PAGP were increased up to 70 and 90 wt%. The study suggests that the interaction between gelatin and PAGP could help to stabilize PAGP/gelatin composite fibrous membranes in aqueous medium and improve the hydrophilicity of pure PAGP nanofibers. Copyright © 2009 Society of Chemical Industry [source] Synthesis and characterization of novel chiral ionic liquids and investigation of their enantiomeric recognition propertiesCHIRALITY, Issue 2 2008David K. Bwambok Abstract We report the synthesis and characterization of amino acid ester based chiral ionic liquids, derived from L - and D -alanine tert butyl ester chloride. The synthesis was accomplished via an anion metathesis reaction between commercially available L - and D -alanine tert butyl ester chloride using a variety of counterions such as lithium bis (trifluoromethane) sulfonimide, silver nitrate, silver lactate, and silver tetrafluoroborate. Both enantiomeric forms were obtained as confirmed by bands of opposite sign in the circular dichroism spectra. The L - and D -alanine tert butyl ester bis (trifluoromethane) sulfonimide were obtained as liquids at room temperature and intriguingly exhibited the highest thermal stability (up to 263°C). In addition, the ionic liquids demonstrated enantiomeric recognition ability as evidenced by splitting of racemic Mosher's sodium salt signal using a liquid state 19F nuclear magnetic resonance (NMR) and fluorescence spectroscopy. The L - and D -alanine tert butyl ester chloride resulted in solid salts with nitrate, lactate, and tetrafluoroborate anions. This illustrates the previously observed tunability of ionic liquid synthesis, resulting in ionic liquids of varying properties as a function of varying the anion. Chirality, 2008. © 2007 Wiley-Liss, Inc. [source] Equilibrium and kinetic investigation of the interaction of model palladium(II) complex with biorelevant ligandsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 10 2010Mohamed M. Shoukry Pd(DME)Cl2 complex was synthesized and characterized, where DME is 2-{[2-(dimethylamino)ethyl]-methylamino}ethanol. Stoichiometry and stability constants of the complexes formed between various biologically relevant ligands (amino acids, peptides, DNA constituents, and dicarboxylic acids) and [Pd(DME)(H2O)2]2+ are investigated at 25°C and at constant 0.1 M ionic strength. The effect of dielectric constant of the medium on the stability constant of Pd(DME)-CBDCA complex, where CBDCA is cyclobutanedicarboxylate, is also reported. The concentration distribution diagrams of the various species formed are evaluated. The kinetics of base hydrolysis of amino acid esters coordinated to Pd(DME)2+ complex is investigated. The effect of the temperature on the kinetics of base hydrolysis of glycine methyl ester complex is studied. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 608,618, 2010 [source] Kinetics of base hydrolysis of ,-amino acid esters catalyzed by the copper(II) complex of N,N,N,,N,-tetramethylethylenediamine (Me4en)INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 12 2006Mahmoud M. A. Mohamed The kinetics of base hydrolysis of glycine-, histidine-, and methionine methyl esters in the presence of [Cu-Me4en]2+ complex is studied in aqueous solutions and in dioxane,water solutions of different compositions at T = 25°C and I = 0.1 mol dm,1. The kinetics of base hydrolysis of glycine and methionine methyl esters is studied at different temperatures. The kinetic data fits assuming that the hydrolysis proceeds in one step. The activation parameters for the base hydrolysis of the complexes are evaluated. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 737,745, 2006 [source] Enantioselective Mannich-Type Reaction Catalyzed by a Chiral Brønsted Acid Derived from TADDOLADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-13 2005Takahiko Akiyama Abstract A novel cyclic dialkyl phosphate was synthesized starting from (+)-diethyl tartrate. Its catalytic activity as a chiral Brønsted acid has been examined in the Mannich-type reaction of a ketene silyl acetal with aldimines as a model reaction. The corresponding ,-amino acid esters were obtained with high enantioselectivity. [source] Synthesis and bio-activity of alkyl/aryl [2-(1,2,4,5-tetrahydro-3-sulfanylene/selenylene naphtha[1,8][1,5,3]diazaphosphocin- 3-yl)methyl amino acid esters]JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2010S. Subba Reddy Synthesis of alkyl/aryl [2-(1,2,4,5-tetrahydro-3-sulfanylene/selenylene naphtha[1,8- f,g][1,5,3]diazaphosphocin-3-yl) methyl amino acid esters] (6,15) was accomplished in three steps. 1, 8-diamino naphthalene (2) was reacted with tris (bromomethyl) phosphine (1) in the presence of triethylamine in dry tetrahydrofuran (THF) under N2 atmosphere to form a PIII intermediate (3). It was converted to the corresponding sulfide (4) and selenide (5) by reacting with sulfur and selenium, respectively. The intermediates 4 and 5 were further reacted with amino acid esters to obtain the title compounds (6,15). The structures of the title compounds were established by elemental analysis and spectral data (IR, 1H, 13C, 31P NMR, and FAB mass). The antimicrobial activity of these compounds was evaluated and they exhibited significant activity. J. Heterocyclic Chem., (2010). [source] Transport of levovirin prodrugs in the human intestinal Caco-2 cell lineJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2006Fujun Li Abstract The transport of 10 amino acid ester prodrugs of levovirin (LVV) was investigated in the human intestinal Caco-2 cell line in order to overcome the poor oral bioavailability of LVV, an investigational drug for the treatment of hepatitis C infection. The prodrugs were designed to improve the permeability of LVV across the intestinal epithelium by targeting the di/tri-peptide carrier, PepT1. Caco-2 cell monolayers were employed to study the transport and hydrolysis properties of the prodrugs. Among all mono amino acid ester prodrugs studied, the LVV-5,-(L)-valine prodrug (R1518) exhibited the maximum increase (48-fold) in permeability with nearly complete conversion to LVV within 1 h. Di-amino acid esters did not offer significant enhancement in permeability comparing with mono amino acid esters and exhibited slower conversion to LVV in Caco2 cell monolayers. Pharmacokinetic screening studies of the prodrugs in rats yielded the highest fold increase (6.9-fold) of AUC with R1518 and in general displayed a similar trend to that observed in increases of permeability in Caco-2 cells. Mechanisms involved in the Caco-2 cell transport of R1518 were also investigated. Results of bi-directional transport studies support the involvement of carrier-mediated transport mechanisms for R1518, but not for the LVV-5,-(D)-valine prodrug or LVV. Moreover, the permeability of R1518 was found to be proton dependent. PepT1-mediated transport of R1518 was supported by results of competitive transport studies of R1518 with the PepT1 substrates enalapril, Gly-Sar, valganciclovir, and cephalexin. R1518 was also found to inhibit the permeability of valganciclovir and cephalexin. These results suggest that R1518 is a PepT1 substrate as well as an inhibitor. © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 95:1318,1325, 2006 [source] Extended application of a chiral stationary phase based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid to the resolution of N -(substituted benzoyl)-,-amino acid amidesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 10 2006Guanghui Tan Abstract A chiral stationary phase (CSP 1) based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid was applied to the resolution of N -(substituted benzoyl)-,-amino acid amides and esters. N -(Substituted benzoyl)-,-amino acid amides were well resolved using a mixture of acetic acid-triethylamine-acetonitrile (0.01 : 0.05 : 100, v/v/v) as an optimum mobile phase while N -(substituted benzoyl)-,-amino acid esters were not resolved at all. In contrast, both N -(substituted benzoyl)-,-amino acid amides and esters were not resolved at all or resolved very poorly on another CSP (CSP 2), which lacks the two N,H hydrogens of the amide tethers of CSP 1. Among the substituents on the benzoyl group of analytes, the nitro group was the best for good resolution of analytes on CSP 1. From these results, the two N,H hydrogens of the amide tethers of CSP 1, the carbonyl oxygen of the amide group of analytes, and the nitro group on the benzoyl group of analytes were concluded to play significant roles in chiral recognition. In addition, various N -(3,5-dinitrobenzoyl)leucine amides with different lengths of N -alkylamide chains were resolved on CSP 1 and N -(3,5-dinitrobenzoyl)leucine N -propylamide was found to show the best chiral recognition in terms of the separation (, = 1.30) and the resolution factor (RS = 3.17). [source] Hydrolysis-improved thermosensitive polyorganophosphazenes with ,-amino-,-methoxy-poly(ethylene glycol) and amino acid esters as side groupsPOLYMER INTERNATIONAL, Issue 9 2005Sang Beom Lee Abstract A series of hydrolysis-improved thermosensitive polyorganophosphazenes with ,-amino-,-methoxy-poly(ethylene glycol) (AMPEG) and amino acid esters (AAEs) of ,N,N -systems' was synthesized, and their properties were evaluated in comparison with the thermosensitive polyorganophosphazenes with methoxy-poly(ethylene glycol) (MPEG) and AAEs of ,O,N -systems', by means of 31P NMR spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). Most of the present polymers showed a lower critical solution temperature (LCST) in the range 32.0,79.0 °C, depending on the kinds of AAE, length of AMPEG and the mol ratio of the two substituents. These polymers exhibited higher LCSTs and faster degradation rates than the MPEG-based polymers. The aqueous solution of poly(ethyl glycinate phosphazene)- graft -poly(ethylene glycol) [NP(GlyEt)0.94(AMPEG350)1.06]n did not show an LCST, which is presumed to be due to its high hydrophilicity, in contrast to [NP(GlyEt)1.01(MPEG350)0.99]n which showing an LCST at 77.5 °C. On the other hand, the polymers with a high content of AAE or with hydrophobic amino acids such as L -aspartic acid and L -glutamic acid, have shown a similar LCST to those of the MPEG-based polymers. The half-lives (t1/2) for hydrolysis of [NP(AMPEG350)1.06(GlyEt)0.94]n at pH 5, 7.4 and 10 were 9, 16, and 5 days, respectively, which are almost 2.5 to 4 times faster than that of the MPEG-based polymers. The LCST of the present N,N -polymers has been shown to be more influenced by salts such as NaCl (,salting-out' effect) and tetrapropylammonium bromide (TPAB) (,salting-in' effect) compared with the ,O,N -system'. Such differences of the ,N,N -systems' from the ,O,N -systems' in thermosensitivity, hydrolysis behavior and salt effect seem to be due to the higher hydrophilicity of the amino group in AMPEG. Copyright © 2005 Society of Chemical Industry [source] Analysis of 3-chlorotyrosine as a specific marker of protein oxidation: the use of N(O,S)-ethoxycarbonyltrifluoroethyl ester derivatives and gas chromatography/mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 8 2003Jens Pietzsch N(O,S) -Ethoxycarbonyltrifluoroethyl amino acid esters are formed by the reaction of amino acids with ethylchloroformate plus trifluoroethanol plus pyridine. The use of these derivatives for a rapid and sensitive determination of 3-chlorotyrosine, a highly specific marker of myeloperoxidase-catalyzed protein oxidation, by using standard gas chromatography/electron impact mass spectrometry, is discussed. Copyright © 2003 John Wiley & Sons, Ltd. [source] Amino-substituted O6 -benzyl-5-nitrosopyrimidines: interplay of molecular, molecular-electronic and supramolecular structuresACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2002Antonio Quesada The structures of eight 2,4,6-trisubstituted-5-nitrosopyrimidines (one of which crystallizes in two polymorphs) have been determined, including seven O6 -benzyl derivatives which are potential, or proven, in vitro inhibitors of the human DNA-repair protein O6 -alkylguanine-DNA-transferase. In the derivatives having an amino substituent at the 4-position, an intramolecular N,H,O hydrogen bond with the nitroso O as an acceptor leads to an overall molecular shape similar to that of substituted purines. There is a marked propensity for these nitroso compounds to crystallize with Z, = 2. The structure of an analogue with no nitroso group is also reported for comparative purposes. Compounds containing the N -alkyl substituents ,NHCH2COOEt, ,NHCH2CH2COOEt and ,NHCH(CH2Ph)COOEt, derived from amino acid esters, exhibit a rich variety of conformational behaviour, and in all of the nitroso compounds the bond lengths provide strong evidence for a highly polarized electronic structure. Associated with this polarization is extensive charge-assisted hydrogen bonding between the molecules, leading to supramolecular aggregation in the form of finite (zero-dimensional) aggregates, chains, molecular ladders, sheets and frameworks. [source] Electrochemical Deallylation of ,-Allyl Cyclic Amines and Synthesis of Optically Active Quaternary Cyclic Amino AcidsCHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2010Peter Abstract Electrochemical oxidation of ,-allylated and ,-benzylated N -acylated cyclic amines by using a graphite anode easily affords the corresponding ,-methoxylated products with up to 76,% yield. Ease of oxidation was affected by the type of electrode, the size of cyclic amine, and the nature of the protecting group. This method was successfully applied to the synthesis of optically active N -acylated ,-alkyl-,-amino acid esters with up to 99,%,ee. [source] | ||||||||||