the one-layer system containing water and DMF, Z(20)Csin catalyzed the peptide bond formation in a higher yield than that by unmodifide chymotrypsin and enabled a synthetic reaction in even an 80% (v/v) DMF media, in which the hydrolytic reaction could not be carried out. Z(20)Csin catalyzed the condensation between some N-acyl amino acids or peptide derivatives and amino acids in 90% ethylacetate,
Complexation equilibrium in a substrate- MgCl2(CaCl2)-Pd/C catalytic system and the influence of its position on asymmetric induction in hydrogenation ofN-acetyl-dehydrophenylalanyl-S-proline
作者:I. N. Lisichkina、A. I. Vinogradova、L. N. Kurkovskaya、M. B. Saporovskaya、V. M. Belikov、T. Yu. Vasil'eva
DOI:10.1007/bf01457764
日期:1996.8
The role of Ca and Mg salts as promoters of asymmetricinduction in hydrogenation ofN-acetyl-dehydrophenylalanyl-S-proline in a substrate— MX2—Pd/C catalytic system was studied. The data of potentiometric titration,1H NMR spectroscopy, and the value of diastereomeric excess (de) of the resultingN-acetyl-R-phenylalanyl-S-proline indicate the complexation of the substrate with calcium and magnesium chlorides
Asymmetric hydrogenation ofN-acetyldehydrodipeptide complexes with Mg(II) and Ca(II) ions
作者:I. N. Lisichkina、A. I. Vinogradova、N. B. Sukhorukova、E. V. Tselyapina、M. B. Saporovskaya、V. M. Belikov
DOI:10.1007/bf00698456
日期:1993.3
N-Ac-DELTA-Phe-AA form labile complexes with Mg(II) ions. Potentiometric titration data show that the carboxyl group of the dehydrodipeptide in them scarcely participates in complexation, unlike the complexes with Ca(II) ions, The hydrogenation of these complexes over Pd/C occurs asymmetrically, the diastereomeric excess being as high as 58%.
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作者:I. N. Lisichkina、A. G. Ivanova、A. S. Peregudov、V. M. Belikov
DOI:10.1023/a:1011397803696
日期:——
The peptide protons in N-acetyl -alpha,beta -dehydrodipeptides (DHDP) dissociate in aqueous methanol in the presence of magnesium salts upon the addition of alkali, which favors the diastereoselectivities of their hydrogenation over Pd/C. By contrast, the N-H bonds of the N-acetyl groups in DHDP seem not to dissociate under these conditions. The dissociation of the peptide N-H bonds in strongly alkaline solutions was studied by F-19 NMR spectroscopy for model compounds containing the 4-FC6H4 fragment.
Complexation as the driving force in diastereoselective hydrogenation of dehydrodipeptides