- ASYMMETRIC HYDROGENATION OF SCHIFF BASE PREPARED FROM alpha -KETO ESTER WITH ALIPHATIC AMINO ACID ESTER.
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Catalytic hydrogenation of Schiff bases prepared from alpha -keto esters with amino acid esters was carried out under various conditions. A significant substituent effect of the alkyl group of the ester moiety of amino acid on the stereoselectivity was observed in the hydrogenation of the Schiff bases prepared from methyl pyruvate with (S)-alanine ester. Higher asymmetric yields were obtained as the ester residue of amino acid ester became bulkier. A clear temperature effect on the asymmetric hydrogenation was also observed. These results could be explained by the chelation mechanism.
- Harada,Shiono
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- Stereochemistry and Total Synthesis of Amavadin, the Naturally Occurring Vanadium Compound of Amanita muscaria
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The structure and stereochemistry of the vanadium compound of Amanita muscaria, amavadin, are elucidated, and a total synthesis of amavadin is reported.It is shown to be the monohydrated complex of VO2+ with two molecules of N-(L-1-carboxyethyl)-N-hydroxy-L-alanine.The ligand belongs to a new type of complexing agents.Amavadin is the first naturally occurring vanadium compound of which the structure of an organic ligand has been established and synthesized.
- Kneifel, H.,Bayer, E.
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- Amino Acids, 5. - Stereoselective Synthesis of α,α'-Imino Dicarboxylic Acids
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The trifluoromethanesulfonates 1, 11, and 26, resp., of enantiomerically pure lactates, β-phenyllactates, and dimethyl α-hydroxyglutarate (25) react with (S)- and (R)-α-amino acid esters 2, 5, 8, 14, 17, 20, and 23, resp., to yield diastereoselectively th
- Effenberger, Franz,Burkard, Ulrike
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p. 334 - 358
(2007/10/02)
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