- Amino Acids, 12. - Syntheses of DL-Cysteines from Acrylic Acid Derivatives
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The addition of sulfenyl chlorides 1 to 2-alkenoic acid esters 2 gives mixtures of 2(3)-chloro-3(2)-thioalkenoic acid esters 3/4, whereas the addition of thiols 7 to methyl 2-chloro-2-propenoate (6) results in the formation of methyl 2-chloro-3-thiopropanoates 3 only.The dependence of the isomerization of 3 to 4 on the reaction conditions was investigated; at higher temperatures the formation of 4 is especially favored.At temperatures below 55 deg C the 2-azido compounds 8 are obtained without isomerization from 3 by reaction with sodium azide in the presence of a PT catalyst.Cysteine derivatives 9 or 10, resp., are obtained by hydrogenation of 8 with H2S/pyridine/H2O or with H2/Re2S; the overall yields of 9 or 10, resp., starting from 6 are as high as 70percent.DL-Cysteine is obtained in good overall yields as hydrochloride hydrate 16 by HCl-catalyzed hydrolysis of the 2-thiazolines 15a*HCl and 15e, which are prepared by HCl-catalyzed addition of thioacetamide (11a) to α-chloroacrylic acid (12) or the amide 13 and consecutive ring closure.
- Effenberger, Franz,Beisswenger, Thomas,Dannenhauer, Fritz
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p. 2209 - 2224
(2007/10/02)
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- Optical Resolution of Racemic S-(Carboxymethyl)cysteine
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Racemic S-(carboxymethyl)cysteine obtained from racemic cysteine is resolved via its ammonium salt (R,S)-3 by preferential crystallization procedure.Furthermore, (R,S)-2 forms with optically active amines separable, diastereomeric salts.Thus, (1R,2S)-2-amino-1-phenyl-1-propanol (4) affords optically pure (R)-S-(carboxymethyl)cysteine in 93 percent yield.The resolution of (R,S)-2 is also possible with (R)-1-phenylethylamine (5).
- Kleemann, Axel,Martens, Juergen
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p. 1995 - 1998
(2007/10/02)
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- Sulfur containing trialkoxybenzoylamino carboxylic acids
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Compounds are prepared of the formula: STR1 wherein A is a straight or branched chain alkylene or alkylidene radical having 2 to 5 carbon atoms and which is substituted by an alkylthio group having 1 to 4 carbon atoms, a carboxymethyl thio group, a carboxyethyl thio group, an alkylsulfonyl group having 1 to 4 carbon atoms, a mercapto group, or the substituent on A together with --COR4 forms a 4 to 7 membered thiolactone ring, or A is substituted by an acylmercapto group wherein the acyl is benzoyl, a benzoyl radical substituted with one, two or three alkoxy groups with 1 to 6 carbon atoms, an alkanoyl radical of 1 to 6 carbon atoms, an alkenoyl radical of 3 to 6 carbon atoms, R1, R2 and R3 are the same or different and are alkyl groups of 1 to 5 carbon atoms and one of R1, R2 and R3 also can be hydrogen or the acyl radical of an alkanoic acid of 2 to 4 carbon atoms and R4 is a hydroxy group or an alkoxy group with 1 to 5 carbon atoms and their pharmacologically acceptable salts. The compounds are pharmacodynamically active and are suited for prophylaxis and treatment of heart illnesses such as cardiac ischemia, cardiac infarct, heart rhythm and circulatory disturbances.
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