L-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). ... 

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... 

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>. 

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... 

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

The synthesis displays interesting stereochemical features. Thus, ethyl 2-(l -benzyloxycarbonylaminoethyl)-(J )-2-thiazoline-4-carboxylate (197) was obtained (0 by the imino-ether route , by condensing L-2-benzyloxy-carbonylaminopropioimino ethyl ether (198) and ethyl L-cysteinate hydrochloride (route A) and (ii) by the dehydration of benzyloxycarbonyl-L-alanyl-L-cysteine ethyl ester (199) (route B). Acidic hydrolysis of the... 

C L - Cysteine ethyl ester hydrochloride - urea complex... 

CgHi NijOg, N-Methylurea oxalic acid (monoclinic), 45B, 8 CgHiijNiiOg, N-Methylurea oxalic acid (orthorhombic), 45B, 8 CgH,gClN303S, L-Cysteine ethyl ester hydrochloride-urea complex, 30B, 208... 

Thiols in Biochemistry.—Space available restricts the present coverage to a few key references. N-Acetyl-cysteine and -penicillamine react with adrenochrome to give the indolyl sulphides (18), (but see also ref. 650) while p-benzoquinone gives two diastereoisomers of (19) with L-cysteine ethyl ester.Other observations with possible significance... 

L-Cysteine ethyl ester (C5H11O2NS), HL (Other reference in Vol.2, p.334)... 

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