- Synthesis of S-trifluoromethyl-containing α-amino acids from sodium trifluoromethanesulfinate and dithio-amino acids
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N-Protonated or N-acetylated dimethyl cystinates and homocystinates react with sodium trifluoromethanesulfinate and t-butyl hydroperoxide to yield the corresponding derivatives of methyl S-trifluoromethyl cysteinate and homocysteinate in a stereospecific manner.Methyl S-trifluoromethyl-N-acetyl cysteinate and homocysteinate are readily saponified, without racemization, by sodium hydrogen carbonate in a water/methanol mixture.
- Langlois, Bernard,Montegre, Denis,Roidot, Nathalie
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- Triply bridged (1,3,5) cyclophanes from cystine and lanthionine linkers-a comparison
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The condensation of benzene 1,3,5-tricarbonylchloride with cystine-di-Me [H2N-CH(COOMe)-CH2-S-S-CH2-CH(COOMe)-NH 2] yielded triply bridged (1,3,5) cyclophane 1, which was shown by detailed spectral studies and molecular orbital calculations to have a D3 symmetry with conformationally identical linkers and a spherical topology. In sharp contrast, the (1,3,5) cyclophane 2 from the rarely studied lanthionine di-Me [H2N-CH(COOMe)-CH2-S-CH2-CH(COOMe)-NH 2], showed only a equatorial twofold symmetry. This work highlights the special properties of the -S-S- bridge in cystine, which makes it an exceptional synthon in nature and organic synthesis.
- Ranganathan,Venkateshwarlu,Babu,Reddy,Basha,Sarma,Vijay,Sastry
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- Synthetic Uses of Thio- and Selenoesters of Trifluoromethylated Acids. 1. Preparation of Trifluoromethyl Sulfides and Selenides
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Trifluorothioacetates (CF3CO-S-R, from (CF3CO)2O and thiols) as well as trifluoromethanethio-or trifluoromethaneselenosulfonates (CF3SO2-Y-R; Y = S, Se; from CF3SO2Na, RYYR, and Br2) can be formally decarbonylated or desulfonylated, respectively, provided that they are photolyzed at 40°C in the presence of 1 equiv of the corresponding disulfide or diselenide. Trifluoromethyl sulfides or selenides are obtained, and the added disulfide (or diselenide) is recovered after reaction. In such a way, S-(trifluoromethyl)cysteine derivatives can be obtained.
- Billard, Thierry,Roques, Nicolas,Langlois, Bernard R.
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p. 3813 - 3820
(2007/10/03)
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- Fluorination of sulfur-containing amino acids: Reaction of xenon difluoride with cysteine derivatives
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The reaction of XeF2 with cysteine derivatives RSCH2CH(NHR)COOR, i.e., S-benzyl-N-trifluoroacetyl-L-cysteine methyl ester, S-benzyl-N-carbobenzoxy-L-cysteine p-nitrophenyl ester, and S-methyl-N-trifluoroacetyl-L-cysteine methyl ester is described.The fluorinated products PhCHFSCH2CH(NHR)COOR, PhCH2SCHFCH(NHR)COOR, and FCH2SCH2CH(NHR)COOR were identified by 1H and 19F nuclear magnetic resonance spectroscopy.PhCH2SCHFCH(NHR)COOR loses HF within 24 hours to give Z- and E-PhCH2SCH=C(NHR)COOR.If the reaction with XeF2 is carried out in the presence of moisture the sulfoxide RS(O)CH2CH(NHR)COOR and sulfone RSO2CH2CH(NHR)COOR are produced.
- Huang, Xiaoling,Blackburn, Barry J.,Au-Yeung, Steve C. F.,Janzen, Alexander F.
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p. 477 - 479
(2007/10/02)
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