Cysteine esters

The reactions of glutathione and cysteine esters have been modeled by the reaction of methanethiol with A-formyloxy-A-methoxyformamide 40 at the BP/ DN //6-31G level.45 The transition state (Fig. 24) possesses similar characteristics... 

J Kovacs, GL Mayers, RH Johnson, RE Cover, UR Ghatak. Racemization of amino acid derivatives. Rates of racemization and peptide bond formation of cysteine esters. J Org Chem 35, 1810, 1970. 

Treatment of compounds, especially esters (see Sections 3.11 and 4.20), /V-substituted cysteine esters (see Section 8.1), and fully substituted /V-methylamino-acid residues (see Section 8.14), by alkali. 

Data taken from ref. 22. Rate constants are not listed for amino acid esters such as methyl 4-amino-n-butyrate where lactamization occurs (see ref. 38). b In the case of the cysteine esters, E = SCH2CH(NH2)C02R EH = HSCH2CH(NH2)C02R EH = SCH2CH(NH3)C02R... 

Table 10 Rate Constants for the Metal Ion-promoted Base Hydrolysis of some Bidentate Species of Cysteinate Esters at 25 °C...

The above stereospecific tiirane polymerisations have generally been run in heterogeneous systems. Such conditions essentially make it impossible to determine the detailed structure of active species involved in these polymerisations. Thus, enantiosymmetric and enantioasymmetric polymerisations of propylene sulphide have also been studied in a homogeneous phase by using chiral cadmium thiolates of cysteine esters and chiral cadmium carboxylates of cysteine and methionine [157,160-164]. The most studied is living polymerisation using the cadmium derivative of the isopropyl ester of (.S)-cysteine [160] ... 

Oxidation processses in the S-acetylated L-cysteine ester derivative... 

The ethylene ketal derivative of prostaglandin E2 (dinopros-tone) possesses much improved solid-state stability (see Chapter 41). Functionalized spirothiazolidines of hydrocortisone and hydrocortisone 21-acetate (Figure 36.6), prepared with cysteine esters or related 3-aminothiols, have improved topical anti-inflammatory activity. It is specnlated... 

Enantiomerically pure thiazoline and thiazole amino acids can be synthesized by condensation reactions between cysteine esters and chiral imino ethers derived from amino acids (Scheme 110)... 

Langford AM, Hobbs MJ, Upshall DG, Blain PG, Williams FM. The effect of sulphur mustard on glutathione levels in rat lung slices and the influence of treatment with arylthiols and cysteine esters. Hum Exp Toxicol. 1996 Aug 15(8) 619-24)... 

The best nitrogen-based ligand system to date for the rhodium-catalyzed hydrosilylation of 1-phenylethanone is the pyridinylthiazolidine system, e.g., methyl (4/ )-2-methyl-2-(2-pyridinyl)-4-thiazolidinecarboxylate (6) and ethyl (4/ )-2-(2-pyridinyl)-4-thiazolidinecarboxylate (7)11, where only a small ligand excess is needed. Ligands of the former type, accessible via a one-step condensation of 2-pyridinecarboxaldehyde and cysteine esters, are commercially available. 

Chiral 2-thiazolidinethiones, e.g., 40, prepared from cysteine esters by the reaction with carbon disulfide23, are used for the enantiotopic differentiation of methylene groups (Section C.). Similarly, carbon disulfide reacts with amino alcohols such as (5)-2-amino-J-butanol or (S)-2-amino-3-methyl-1-butanol (valinol) to give the 2-thiazolidinethiones (S)-ETT 42 and (S)-IPTT 4124 which have been used as auxiliaries (after Y-acylation with carboxylic acids and dicyclo-hexylcarbodiimide) in acylimonium ion cyclizations (Section D.I.4.5.). 

In the case of the cysteine esters, E = SCH2CH(NH2)C02R EH = HSCH2CH(NH2)C02R EH = SCHjCHCNHjiCOjR... 

The first preparations of optically active thiirancarboxylic acids have been reported.Treatment of the cysteine esters (i )-(321 R = Me) with NaN02 and HCl causes deaminative cyclization to chiral (5)-(322 R = Me). For the parent acid (R)-(321 R = H), optical yields of (5)-(322 R = H) of 53 and 60% were obtained in dilute HCl or MeC02H, respectively. 

Lailey AF, Hill L, Lawston IW, Stanton D, Upshall DC. Protection by cysteine esters against chemically induced pulmonary edema. Biochem Pharmacol. 1991 42 S47 S54. 

On the other hand, reaction of D-glucorono-3,6-lactone 55 with L-cysteine ester 56 gave stereoselectively the bicyclic thiazolidine lactam 57, a precursor for polyol peptidomimetics [90,91]. The thiazoUdine 58 was found to be... 

CsjCMoOFs] ligand=ethyl-L-cysteine ester 303 1.54 73C15... 

Figure 4 Structure of a cadmium thiolate of cysteine ester and a cadmium carboxylate of methionine.

A. F. Lailey, L. Hill, I. W. Lawston, D. Stanton and D. G. Upshall, Protection by cysteine esters against chemically-induced pulmonary oedema, Biochem. Pharmacol, 1991, 42, S47-S54. 

---