- REDUCTIVE CLEAVAGE OF SULFUR OF SULFUR-SULFUR BONDS WITH SODIUM HYDROGEN TELLURIDE
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Sodium hydrogen telluride is shown to be an effective reagent for reduction of alkyl, aryl and functionally substituted disulfides to thiols in good yield under mild conditions.Organic thiosulfites (Bunte salt) also give thiols through the corresponding disulfide on reaction with sodium telluride.
- Kong, Fangming,Zhou, Xunjun
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p. 3143 - 3150
(2007/10/02)
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- 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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