L-cystine derivative

The one-pot synthesis of lanthionines starting from thiosulfinates and cysteines and subsequent addition of tris(diethylamino)phosphine was not successful. Moreover, with this method based on L-cystine derivatives only L-lanthionines have been synthesized. In this context it is worth noting, that alternative and possibly more efficient methods can be applied for the synthesis of the unsymmetrically protected cystines as intermediates (Section 6.1.3). 

The synthesis of 3-alkyl-substituted 1,2-thiazetidine 1,1-dioxides starts by transformation of the amino acids L-Val, L-Leu, L-Ile, and L-Phe into amino alcohols. These ate converted via the bromides to the corresponding thiols 161. Immediate oxidative chlorination affords either sulfonyl chloride hydrochlorides or sulfonic acids 162 which are transformed into the parent /3-sultams 163 <2004HCA90>. Similarly, L-cystine derivatives 164 have also been transformed into the parent /3-sultams 165 by oxidative chlorination followed by cyclization (Scheme 50) C1997LA1261, 2004HCA90>. 

A similar synthetic scheme was adopted by Nadel [13] to prepare isothiazolones 34 and 35 from L-cystine derivatives transformed into the corresponding cystine fozs-N-(methylamides) 33a-c (Et0C02Cl, TEA in CH2CI2 then MeNH2/H20, 69- 73%) (Scheme 10). As reported in Table 1, several parameters were evaluated in order to find the best reaction conditions to produce the different isothiazolone derivatives 34 (43-63%) or 35 (52-66%). As by-products, the polyhalogenated compounds 36 and 36 (not separable) were formed in some instances. Finally, the deprotection of the amino group... 

There are two reports describing the preparation of derivatives of 1,2-thiazetidine-1,1-dioxide. The sulfur atom in L-cystine diethyl ester was oxidized and the corresponding sulfonyl chloride was cyclized with ammonia (Scheme 3) (60CB784). A similar transformation used protected )3-homocysteine as starting material (94LA251). 

Most of the reduced thiazole derivatives were obtained from the reaction between l -Cys or its esters with aldehydes or ketones. L-Cystine reacts with formaldehyde at room temperature to give 4(f ) -thiazolidinecarboxylic acid 32 without racemization [36JBC(114)341 37JA200 78JMC1070]. 

Ethyl sulfonamidomethylglycinate was prepared from L-cystine in several steps it was then transformed with l,l -carbonyldiimidazole into thiadia-zine derivative 51 (84JMC228). 

A further approach for the synthesis of nonsymmetrically protected lanthionines is the conversion of thiosulfinates of symmetrically protected cystine derivatives into nonsymmetrically protected cystines via a reaction with a cysteine derivative and subsequently the conversion of the resulting unsymmetrically protected cystine into the nonsymmetrically protected lanthionines with a tris(dialkylamino)phosphineJ26l The oxidation of the symmetrically protected cystine, e.g. A,AT-bis(benzyloxycarbonyl)-L-cystine diethyl ester, of one stereochemical configuration to the thiosulfinate with m-chloroperoxybenzoic acid is essentially quantitative. The nonsymmetrical cystine is then formed in a subsequent step by the addition of the /V-/er/-butoxycarbonyl-L-cysteine tert-butyl ester derivative to give N-Z-N -Boc-L-cystine ethyl ferf-butyl diester. The desired 2f ,6f -lanthionine is then formed in the presence of P(NEt2)3 in yields of >50%. 

The synthesis of four out of eight possible stereoisomers of 3-methyllanthionine [(25,35,67 ), (25,37 ,67 ), (25,35,65), (25,37 ,65)] has been achieved using the reaction of Z-protected 3-methyl-D-cysteine with d- or L-3-chloroalanine in yields of 35—53% J64 The methyl-D-cys-teine stereoisomers were obtained by two routes. Firstly from (25,35)-threonine via O-tosylation and subsequent inversion of configuration by nucleophilic attack with thiobenzoic acid. The resulting derivative was debenzoylated and oxidized to the respective cystine derivative prior to the reduction with Zn/HCl to give the eryt/u-o-3-methyl-D-cysteine... 

The use of Trt-protected 3-iodoalanines for lanthionine synthesis is also a highly promising method for the synthesis of 3-methyl- and 3,3-dimethyllanthionines. 40 This method is based on the use of A-trityl-3-iodoalanine benzyl ester (54) and the symmetrically protected bis(Boc)-cystine-derivative dimethyl esters derived from L-t/treo-3-methylcysteine and d-penicillamine. Yields of the respective lanthionine derivatives are >80% however, enantiomeric excesses have not been determined for the 3-substituted lanthionines (Scheme 18). 

A disulfide-linked bis(aminoethanol) 82 prepared from L-cystine also catalyzes the borane reduction of ketones. Other oxazaborolidine derivatives are obtained from 83, 84, " and 85, " and polymer-bound species. Those derived from the ephedra bases find use in the asymmetric reduction of imines. bicyclic oxazaborolidine generated... 

Bis-V-tert-hutyloxycarhonyl-L-cystine, [10389-65-8] M 440.5, m 144.5-145 , [a] g -133.2 (c 1, MeOH), 2.9. Crystallise the cystine derivative from EtOAc by adding hexane [Ferraro... 

Attempts have been made to correlate the chiroptical properties with the conformations of several sulfur-containing amino acids (Jung et al., 1973 Ottnad et al, 1975). Several reports describe conformations and chiroptical properties of L-cystine and its derivatives (Coleman and Blout, 1968 Casey and Martin, 1972 Strickland et al, 1974 Mattice, 1977). The CD data have been analyzed in terms of the chirality of the disulfide chromophore (Strickland et al, 1974) representing different conformer populations in solution. 

Oxidized L-cysteine. See L-Cystine Oxidized keratin Synonyms Keratin, oxidized Definition Material derived chemically from keratin by oxidation with hydrogen peroxide Uses Hair conditioner, skin conditioner in cosmetics... 

A soln. of N-carbobenzoxy-S-benzylthiomethyl-L-cysteinylglycine in ca. 98%-formic acid added with swirling to an aq. partial suspension of mercuric acetate so that a clear soln. is obtained, after 15 min. at room temp, ethanedithiol added to minimize thiazolidine ring formation, after 15 min. HgS passed in, the precipitated mercuric sulfide removed by filtration, and the product isolated as the cystine derivative di (carbobenzoxy)-L-cystinyldiglycine. Y 79%. F. e. s. P. J. E. Brownlee et al., Soc. 1964, 3832. 

In addition to rigid bisurea macrocycles, more flexible bisurea-derived macrocycles can also form tubular assemblies in the solid state. For example, Rangana-than and co-workers reported that macrocyclic bisureas prepared from L-cystine was able to form nanotubes of uniform shape and internal diameter [52], The two adjacent rings were bound together by two hydrogen bonds from bisamides and four hydrogen bonds from bisureas. The tubular structure was further stabilized by... 

Conversely, according to observations of du Vigneaud, Loring, and Craft (133) with rabbits, the sulfur of acetyl and, formyl derivatives of l-cystine is oxidized just about as in the case of i-cystine itself. However, the sulfur of the corresponding derivatives of d-cystine is considerably more resistant to oxidation than the sulfur of d-cystine. 

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