- Imination of sulfur-containing compounds: XXXV. New preparation method and oxidative benzenesulfonylimination of unsymmetrical disulfides
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A new preparative method of synthesis was developed for unsymmetrical and symmetrical disulfides. This method involves sulfenylation of sodium thiolates with N-arenesulfenyl-N,N′-bis(arenesulfonyl)sulfinamidines. Imination of unsymmetrical disulfides with sodium chloroamides of sulfonic acids occurs at the more nucleophilic sulfur atom, affording N,N′ -bis(arenesulfonyl)sulfinamidines and symmetrical disulfides.
- Koval'
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p. 232 - 234
(2007/10/03)
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- Synthesis and Acylation of Salts of L-Threonine β-Lactone: A Route to β-Lactone Antibiotics
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The synthesis and N-acylation of β-lactones derived from L-threonine and L-allo-threonine were investigated.Treatment of N--L-allo-threonine (7b) with 4-bromobenzenesulfonyl chloride in pyridine at -43 to 0 deg C gives the corresponding β-lactones 8a and 8b, respectively, in 45-56 percent yields.These can be deprotected with thiophenol or p-thiocresol in the presence of p-toluenesulfonic acid to produce optically pure salts of L-threonine β-lactone (9a) and its allo isomer 9b (65-92percent).Compound 9a is readily acylated by reagents such as acid chlorides (e.g., acetyl, benzoyl) and mixed anhydrides to afford N-acyl β-substituted β-lactones such as 10 (antibiotic SQ 26,517), 14, 15, and 16 in good yield (84-92percent).Reaction of β-lactones 8a, 8b, and 9a with HBr in acetic acid results in nucleophilic ring opening by bromide at the β-position to give pure isomers of 2-amino-3-bromobutanoic acid.
- Pu, Yunlong,Martin, Fionna M.,Vederas, John C.
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p. 1280 - 1283
(2007/10/02)
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