- Small peptides as modular catalysts for the direct asymmetric aldol reaction: Ancient peptides with aldolase enzyme activity
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Simple peptides and their analogues having a primary amino group as the catalytic residue mediate the direct asymmetric intermolecular aldol reaction with high stereoselectivity and furnish the corresponding aldol products with up to 99% ee; this intrinsic ability of highly modular peptides may explain the initial molecular evolution of aldolase enzymes. The Royal Society of Chemistry 2005.
- Zou, Weibiao,Ibrahem, Ismail,Dziedzic, Pawel,Sunden, Henrik,Cordova, Armando
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p. 4946 - 4948
(2007/10/03)
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- A novel, one-pot preparation of N-methyl-α-amino acid dipeptides from oxazolidinones and amino acids
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A new synthetic method has been developed to prepare N-methyl dipeptides in one-pot directly from oxazolidinones. Treatment of oxazolidinone 1 with an amino ester yields an intermediate N-hydroxymethyl dipeptide 3, which is treated with TFAA and triethyls
- Dorow,Gingrich, Diane E.
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p. 467 - 470
(2007/10/03)
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- Papain-catalyzed esterification of N(α)-protected amino acids and dipeptides with ethanol in different organic systems
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The papain-catalyzed esterification of N(α)-protected amino acids and dipeptides with ethanol in mostly hydrophobic organic solvent systems containing low amounts of water has been investigated. The influence of various parameters, such as the amount of added water, reaction time, temperature and pH of added buffer, on the yield of ester was studied first on the model substrate Z-Ala. The optimized reaction conditions were then used for esterification of a series of N(α)-protected amino acids and dipeptides.
- Braun,Kuhl
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p. 203 - 206
(2007/10/03)
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- KINETICS OF THE ALKALINE HYDROLYSIS OF SEVERAL N-BENZYLOXYCARBONYLDIPEPTIDE METHYL AND ETHYL ESTERS
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The reaction rates of the alkaline hydrolysis of synthesized N-protected dipeptide methyl and ethyl esters were studied systematically.From the kinetic data the energies of activation, the pre-exponential factors and the reference values at 40 deg C were calculated.The rate of hydrolysis shows to be strongly dependent on the C-terminal amino acid in the sequence Gly >> Ala/Met/Phe > Leu >> Val/Pro.Surprisingly the N-terminal amino acid also exerts an effect, but in a different sequence.N-Terminal Phe in particular shows a relative accelerating effect.Remarkable is the significantly faster ester hydrolysis of glycine containing dipeptide ethyl esters in ethanol/water compared to the corresponding methyl esters in methanol/water.
- Hoogwater, D. A.,Peereboom, M.
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p. 5325 - 5332
(2007/10/02)
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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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- ENANTIOSELECTIVE SYNTHESIS OF PEPTIDES USING (1R)-3-HYDROXY-1,8,8-TRIMETHYL-3-AZABICYCLOOCTANE-2,4-DIONE ((+)-N-HYDROXYCAMPHORIMIDE) AN ACTIVE ESTER GROUP
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The enantioselective coupling reaction of N-protected amino acid (+)-N-hydroxycamphorimide esters (-OCamp) with racemic amino acid esters is discussed.The coupling reaction of several amino acids showed high enantioselectivity.Keywords-enantioselective synthesis; (+)-N-hydroxycamphorimide; peptide, active ester; coupling reaction
- Takeda, Kazuyoshi,Tsuboyama, Kanoko,Suzuki, Akira,Ogura, Haruo
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p. 2545 - 2548
(2007/10/02)
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- 2-HALOVINYL ARYL SULFONES: NEW COUPLING REAGENTS FOR CARBOXAMIDE FORMATION
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E-2-Chlorovinyl p-nitrophenyl sulfone 6 and 2-bromo-2-trifluoromethylvinyl phenyl sulfone 7a reacted with carboxylic acids in the presence of a molar equiv of Et3N affording the corresponding 2-acyloxyvinyl sulfones 8, 11, 17, 18, 22, 25, 28 and 29.The latter, on treatment with amines, gave amides 9, 13, 19, 23 and 26 and peptides 30 and 32.These reagents 6 and 7a were also used for the formation of N-methylanilides 13d, 13e, 19d, 23 and 26.Particularly, 6 was successfully used for synthesis of a macrocyclic lactam 23 involving a N-methylanilide moiety.The amidation reac tions proceeded under essentially neutral conditions.Therefore, base-sensitive β-hydroxycarboxy-N-methylanilides such as 26, whose structural unit was involved in maytansine 5, could be prepared by the present method.The reagent 6 was also effective for the preparation of peptides such as Val-N-MeVal derivatives (e.g.32), which were difficult to prepare by other methods.
- Shimagaki, Masayuki,Koshiji, Hiroko,Oishi, Takeshi
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- OPTICALLY ACTIVE N-HYDROXYTARTRIMIDES FOR ENANTIOSELECTIVE PEPTIDE SYNTHESIS
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Preparations of optically active N-hydroxytartrimides were achieved. 1,3,4-Trihydroxysuccinimide ester of Z-L-alanine and 1-hydroxy-3,4-diacetoxysuccinimide ester of Z-D-alanine were allowed to react with D,L-alaninate to produce L-L form and D-D form of
- Teramoto, Takero,Deguchi, Mikito,Kurosaki, Toshikazu,Okawara, Makoto
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p. 1109 - 1112
(2007/10/02)
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