Cysteine ethyl ester

The amino acid complexes [TcNCl(L)(PPh3)] (HL=L-cysteine, L-cysteine ethyl ester, cysteamine) have been prepared from [TcNC PPlfj ] or ASPI14 [TcNCU]/PPh3 [88]. The crystal structure of the L-cysteine ethyl ester complex 21 shows a Tc=N bond length of 1.605(3) A and the Tc atom displaced by 0.594(1) A above the square basal plane [88]. Other structurally characterized examples are the square pyramidal 22 with ONSP coordination and Tc=N 1.611(3) A [81], and 23 with NSPC1 coordination and Tc=N 1.615(7) A [89],... 

Table 11 Arrhenius activation energies, entropies of activation and rate constants at 298 K for reaction of iV-benzoyloxy-iV-benzyloxybenzamides 28 with L-cysteine ethyl ester in d4-methanol...

In reactivity, the same series of mutagens exhibited positive Hammett correlations for AaiI acid catalysed solvolysis (p — + 0.32) and SN2 reactivity with A-methyl-aniline (p — + 1.7), hydroxide (p — +0.55) and L-cysteine ethyl ester (p — + 1.1), all reactions in which the benzoyloxyl group leaves with electrons and which are therefore accelerated by electron-withdrawing groups. The negative Hammet p-value for... 

OPA in combination with chiral thiols is one method used to determine amino acid enantiomers. A highly fluorescent diastereomeric isoindole is formed and can be separated on a reverse-phase column. Some of these chiral thiols include N-acetyl-L-cysteine (NAC), N-tert-butyloxy-carbonyl- L-cysteine (Boc-L-Cys), N-isobutyryl- L-cysteine (IBLC), and N-isobutyryl- D -cysteine (IBDC). Replacing OPA-IBLC with OPA-IBDC causes a reversal in the elution order of the derivatives of D- and L-amino acids on an ODS column (Hamase et al., 2002). Nimura and colleagues (2003) developed a novel, optically active thiol compound, N-(tert-butylthiocarbamoyl)- L-cysteine ethyl ester (BTCC). This reagent was applied to the measurement of D-Asp with a detection limit of approximately 1 pmol, even in the presence of large quantities of L-ASP. 

Rates of reaction were moderately fast. Glutathione reacted rapidly in DMS0-rf6/D20 ( 2 ° ca 2 X 10 lmol s ) and a series of A-benzoyloxy-A-benzyloxybenzamides (139) and (L)-cysteine ethyl ester in methanol-(f4 reacted with low a values (8-16 kcal mol ) and negative AS (—19 to —43 calK mol ), similar to their reaction with anilines. Bimolecular rate constants at 298 K (Table 8) correlated positively with Hammett a constants with slightly lower sensitivity p =. as opposed to p =. l for A-methylaniline). ... 

Condensation of dopachrome methyl or ethyl esters with cysteine ethyl ester in pH 6.8 aqueous phosphate buffer led to the l,2-dihydro-3//,8//-pyrrolo[2,3-/ ][l,4]benzothiazines (87), as shown in... 

PEPTIDE SYNTHESIS USING l-(4-CHLOROPHENYL)-3-(4 -ICTHYL-l -PIPERAZINYL)-2-PROPYN-l-flNE AS REAGENT BENZYLOXYCARBONYL-L-ALANYL-L-CYSTEINE ETHYL ESTER AND BENZYLOXYCARBONYL-L-ASPARTYL-(tert-BUTYL ESTER)-L-PHENYLALANYL-L-VALINE ICTHYL ESTER... 

Thiazoline (8) is readily available from cysteine ethyl ester and benzonitrile. The separated enantiomers 18 and ent-18 can be converted to (R)- and (5)-2-methylcysteine ethyl ester hydroehloride 5 x HCl and ent-5 x HCl under standard conditions. 

Varmenot N, Remita S, Abedinzadeh Z, Wisniowski P, Strzelczak G, Bobrowski K (2001) Oxidation processes of N,S-diacetyl-L-cysteine ethyl ester Influence of S-acetylation.Chem A 105 6867-6875. 

Reaction of L-cysteine ethyl ester hydrochloride 194 with CS2 in the presence of triethylamine in DCM resulted in the formation of thiazolidine ester 195 in 85% yield (Scheme 75) <2001TL8559>. 

As mentioned, the amino acid cysteine is thought to be involved in the biosynthesis of trichochromes. Cysteine reacts with 4-methyl-O-benzoquinone to give 22, which on treatment with mineral acid gives the trichochrome chromophore system,43 and reactions of cysteine ethyl ester and of 2-aminoethanethiol with quinones were studied to elucidate and duplicate the natural synthesis.41,42... 

Cysteine ethyl ester (99) reacts with p-benzoquinone41 to give a dimeric product (100) and not the quinonoid structured product (101) as reported by Kuhn and Hammer.144... 

A soln. of androstanol-17a-one-3 and cysteine ethyl ester hydrochloride in pyridine kept at room temp, overnight —> ethyl sptVo-17a-hydroxy-androstane-S -thiazolidine-l -earboxylate. Y 83%. (F. e. and limitations s. S. Lieberman, P. Brazeau, and L. B. Hariton, Am. Soc. 70, 3094 (1948).)... 

Ehrler and Farooq" prepared 1187 via a stepwise construction of the three thiazoline rings, introduction of the styryl group, and preparation of the oxazole ring (Scheme 1.333). Condensation of L-cysteine ethyl ester hydrochloride 1284 (R = C2H5) with an imino ether derived from cinnamamide was unsuccessful, owing to complications from Michael addition. This necessitated a strategy in which the styryl double bond was introduced after assembly of thiazoline rings. 

Cobalt nanoparticles (surface modified with L-cysteine ethyl ester) ethanol wet are available as 10mn black powder (wet with EtOH) which is best used within 3 months. The material can be easily transferred into stable aqueous suspensions, and can be used as a starting material for surface modifications (e.g. dextran coating) or the preparation of magnetic polymer microspheres. 

BTCC AT-tert-Butylthiocarbonyl-L-cysteine ethyl ester... 

Joshi, G., S. Hardas, R. Sultana et al. Glutathione elevation by ganuna-glutamyl cysteine ethyl ester as a potential therapeutic strategy for preventing oxidative stress in brain mediated by in vivo administration of adriamycin Implication for chemobrain. 

Radiochromatographic techniques have been used to determine the rates of oxidation of cysteine by pertechnate ion, Tc04. The technetium(vu) is reduced by the thiol (and cysteine ethyl ester) to form a Tc complex which involves both S- and 7V-co-ordination of the amino-acid. The rate law is first order with respect to both [Tc ] and [RSH]. A hydrogen-ion dependence observed is attributed to the formation of pertechnic acid, the rate-determining step being the nucleophilic attack by the thiol at the metal centre of HTCO4. The oxidation of RSH (R=Et, Pr, or Bu) has been studied over the range 20—40 °C in aqueous alkaline solutions in the presence of metal phthalo-cyanines. The reaction is zero order with respect to [thiol], first order in phthalocyanin and decreases in the order M = Co>Mn> V>Feii. No effects are observed from the nature of the alkali cation. 

Hydrogen bonding 379-396—see also Self-association in L-cysteine 139-141,143 in L-cysteine ethyl ester hydrochloride urea complex 137, 143... 

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