Cysteine phenyl

L-cysteine Phenyl-L-oysteine 32 b Zbnrsky and Young (1943a)... 

Guy has explored copper-mediated S-arylation of thiols and aryl boronic acids [67]. Earlier studies revealed that the reactions were slow for S-arylation under the conditions developed previously for N- and O-arylation reactions because of a significant disulfide formation. However, it was shown later that the reaction of a wide range of electronically diverse aryl boronic acids with a range of thiolate substrates proceeded well when heated at 155 °C in DME affording cross-coupled products in good yields. Similarly cysteine phenyl sulfide 103 and an arylthio glycoside 104 were also prepared in 50-80% yields (Scheme 3.46). 

Reaction with another suitably protected -nitro-phenyl ester now adds the next amino acid (another cysteine),... 

The desulfinase enzyme was reported to have narrow substrate specificity. In addition to HBPSi, only 2-phenyl benzene sulfinate was reported to serve as a substrate [164], It was found to be inactive against benzene sulfinate, cysteine sulfinate, benzene sulfonate, /7-toluene sulfonate, 1-octane sulfonate, methane sulfonate, and taurine. This enzyme was found to be inhibited by HBP beginning at 0.5 mM with complete loss of activity at 9 mM HBP, but was not affected by sulfite. 

Peptide Cystine + cysteine Lysine Histidine Glycine Aspartic Glutamic Arginine acid acid Alanine Proline Tyrosine Valine Leucine Phenyl- Unala- iden-nine tifled... 

The cysteine conjugates appeared to be key metabolil es, occupying pivotal positions in the pathway. S-(Pentachloro-phenyl)cysteine was not demonstrated in vitro, but it was a minor metabolite in peanut plants. This anomoly appeared to be due to the kinetics of the various reactions. A cysteine conjugate was clearly shown to be a key intermediary metabolite in the metabolism of the GSH conjugate of atrazine in sorghum (Figure 1). 

The reaction of diazomethane with 2-phenyM-(sulfanylmethylene)-5(4//)-oxazolone 665, readily obtained from 4-(chloromethylene)-2-phenyl-5(4//)-oxazo-lone 394, generates the intermediate spirocyclopropane oxazolones 666 and 667, respectively. Both 666 and 667 were independently elaborated to the 2-sulfanyl-1-aminocyclopropanecarboxylic acid derivatives 668 and 669—a novel class of conformationaUy constrained masked cysteines (Scheme 7.210). Representative examples of spirocyclopropane oxazolones are shown in Table 7.47 (Fig. 7.58). 

A full-length human csk DNA that codes for Csk, a 50-kDa protein that catalyzes the phosphorylation of a tyrosine within the C-terminal tail of Srk, was inserted in a plasmid and in-frame with a modified intein-chitin binding domain (CBD) encoding sequence, where intein is a protein-splicing element. 130 The expressed protein underwent a conversion into a thioester of the N-terminal cysteine of the intein, but the normal second step of an intein splicing did not occur. The protein was then bound to a chitin resin and washed. The resin containing the bound protein was treated with 2% benzenethiol to cleave the thioester and give the free phenyl thioester, which was immediately treated with one of the synthetic... 

Whilst lanthionine is commercially available from a number of sources, 3-methyllanthionine is generally difficult to obtain indeed, literature for the synthesis of unprotected MeLan is also scarce. One such procedure is the synthesis of MeLan from L-cysteine and (4Z)-4-ethylidene-2-phenyl-l,3-oxazol-5(4//)-oneJ58l... 

Recently, a series of 4-substituted-3-Cbz-phenyl-(5-lactams (Fig. 37) has been identified as a novel class of cysteine protease inhibitors [364]. 

For catalytic waves of hydrogen evolution in ammoniacal cobalt solutions, it has been observed (132) that ery/Aro-phenylcysteine gives a higher catalytic wave than the threo form (Fig. 28). These differences can be explained partly by differences in acid dissociation constants, and partly by variations in the stability constants of the cobalt-phenyl-cysteine complexes. 

Fig. 28. Steric effects on catalytic waves of phenyl cysteins. To 0.001 M cobaltous chloride, 0.1 M ammonia, 0.1 M ammonium chloride added 3 X 10-5iMT erylhro-and ttra>-phenylcystein. Curves starting at —0.8 V S.C.E., 200 mV/absc., full scale sensitivity 28 p.A...

Jew and Park also succeeded in expanding the methodology to the similar asymmetric alkylation of 2-phenyl-2-thiazoline-4-carboxylic acid ester 55 to furnish optically enriched a-alkyl cysteine derivatives 56 (Scheme 5.27) [29]. 

As early as 1977 Pracejus et al. investigated alkaloid-catalyzed addition of thiols to a-phthalimido acrylates, methylene azlactones, and nitroolefins [56a]. In the former approach, protected cysteine derivatives were obtained with up to 54% ee. Mukaiyama and Yamashita found that addition of thiophenol to diisopropyl mal-eate in the presence of cinchonine (10 mol%) proceeds in 95% yield and that the product, (S)-phenylthiosuccinate, was formed with 81% ee [56b]. The latter Michael adduct was used as starting material for preparation of (R)-(+)-3,4-epoxy-1-butanol. In the course of an asymmetric total synthesis of (+)-thienamycin Ike-gami et al. studied the substitution of the phenylsulfonyl substituent in the azetidi-none 69 by thiophenol in the presence of cinchonidine (Scheme 4.34) [56c]. This substitution probably proceeds via the azetinone 70. In this reaction the phenyl-thioazetidinone 71 was obtained in 96% yield and 54% ee. Upon crystallization, the optically pure substitution product 71 was obtained from the mother liquor... 

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