Asymmetric synthesis of 2-substituted butane-1,4-diols by hydrogenation of homochiral fumaramide derivatives
Diastereoselective hydrogenation of homochiral fumaramides 1 derived from (2R)-Oppolzer's sultam was observed by analysis of the 1H NMR spectra of the succinamide mixtures with de's of 77-88%. Reduction of these succinamides using LiAlH4 gave the corresponding (2S)-butane-1,4- diols and established that addition of hydrogen takes place selectively on the re-face of fumaramides 1. The stereoselectivity was confirmed by estimating the ee's from the 19F NMR spectra of the Mosher's diesters of the diols. This methodology was applied to the synthesis of selected pyrrolidine natural products in homochiral form.
Jawaid, Samaila,Farrugia, Louis J.,Robins, David J.
p. 3979 - 3988
(2007/10/03)
Preparation of (S)-2-Substituted Succinates by Stereospecific Reductions of Fumarate and Derivatives with Resting Cells of Clostridium formicoaceticum
Fumarate derivatives have been reduced to (S)-2-methylsuccinate 2a, (S)-2-ethylsuccinate 3a and (S)-2-chlorosuccinate 4a in up to 1 M concentrations with Clostridium formicoaceticum.Formate was the electron donor and viologens or anthraquinone-2,6-disulphonate acted as artificial electron mediators.Reductions with freeze-dried cells in 2H2O-buffers led to the (2R,3S)--dideuterated succinate derivatives.The productivity numbers ranged from 450 to 5000 and the enantiomeric excess of all (S)-2-substituted succinates was >/= 99percent.
Eck, Richard,Simon, Helmut
p. 13631 - 13640
(2007/10/02)
Enantiospecific synthesis of 3-substituted aspartic acids via enzymic amination of substituted fumaric acids
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Akhtar,Botting,Cohen,Gani
p. 5899 - 5908
(2007/10/02)
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