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  • 1
    ISSN: 1438-2199
    Keywords: Amino acids ; Non-proteinogenic optically active amino acids ; D- and L-enantiomers ; Dehydroamino acids ; Chiral rhodium catalysts ; Asymmetric hydrogenation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Non-proteinogenic amino acids play an increasing role in oligopeptide chemistry. Their pharmacological and chemical properties, caused by D-configuration and “unnatural” residues, are more and more used for drug design. Different methods of asymmetric synthesis have been developed during the last decade to prepare “unusual” amino acids. One of them, the asymmetric hydrogenation of dehydroamino aids catalyzed by chiral rhodium (I) complexes, will be described. A series of examples, D- and L-configured, like naphthyl-, thienyl-, furyl-, and pyridylalanines, as well as phenylalanines substituted by chlorine, fluorine, p-nitro, p-methyl, p-trifluoromethyl, p-isopropyl, and p-tert-butyl have been prepared and characterized. Some analytical data like melting points and values of optical rotation are summarized in tables.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Amino acids 17 (1999), S. 369-376 
    ISSN: 1438-2199
    Keywords: Amino acids ; Non-proteinogenic dipeptides ; Dehydrodipeptides ; Diastereoselectivity ; N-Boc-Dehydroamino acids ; Asymmetric hydrogenation ; Chiral rhodium catalysts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary N-Boc protected non-proteinogenic dipeptides with D,L-and L,L-configuration were prepared by catalytic asymmetric hydrogenation of the corresponding dehydrophenylalanyl-(L)-phenylalanine derivatives. The configuration of the new stereogenic centre depends first of all on the catalyst configuration and is less influenced by the substrate configuration. Diastereomeric excesses in the range of 80–96% de could be increased up to 99% by recrystallization. Analytical data of selected new compounds are given.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1438-2199
    Keywords: Amino acids ; Non-proteinogenic optically active amino acids ; Dehydroamino acids ; Chiral rhodium catalysts ; Asymmetric hydrogenation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary (Z)-α-[(Benzyloxy)- or (tert.-butyloxy)carbonylamino]-β (thienyl)-or (furyl)-acrylic acids and their esters were prepared by known methods and hydrogenated to the corresponding optically active alanine derivatives with optical yields in the range of 58–93% ee using the cationic rhodium complex of “PROPRAPHOS”.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1438-2199
    Keywords: Amino acids ; Dipeptide derivatives ; Non-proternogenic optically active dipeptide esters ; Dehydrodipeptides ; Chiral rhodium catalysts ; Asymmetric hydrogenation ; Diastereoselectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary N-[(Z)-N-Benzoyl- orN-Boc-(2-fluorophenyl)dehydroalanyl]-(R)-or (S)-phenylalanine esters were synthesized and hydrogenated to give the corresponding dipeptide derivatives with optical yields in the range of 53–87%de using the cationic rhodium complexes of PROPRAPHOS and BPPM. The efficiency of chiral diphosphine ligands as well the effect of the chiral center in the substrate on the catalytic asymmetric induction was studied.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 323 (1981), S. 667-672 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of the Enantiomers of trans-2,3-Bis-(diphenylphosphinomethyl)-norbornene-(5)
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 325 (1983), S. 1021-1026 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of the Enantiomers of trans-11,12-Bis-(diphenylphosphinomethyl)-9,10-dihydro-9,10-ethanoanthracene and its Perhydrogenated Derivative
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Reaction kinetics and catalysis letters 24 (1984), S. 153-156 
    ISSN: 1588-2837
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Энантиомеры транс-11, 12-бис-(дифенилфосфинометил)-9, 10-дигидро-9,10-эта ноантрацена и его пергидрированного производного были синтезированы и исследованы как лиганды в асимметрическом гидрировании прохиральных олефиновых субстратов. Наблюдались разницы в селективности и отчасти высокие оптические выходы.
    Notes: Abstract The enantiomers of trans-11, 12-bis-(diphenylphosphinomethyl)-9, 10-dihydro-9,10-ethanoanthracene and its perhydrogenated derivative were prepared and used as ligands in the asymmetric hydrogenation of prochiral olefinic substrates. Different selectivities and partiallyhigh optic al yields could be observed
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Reaction kinetics and catalysis letters 16 (1981), S. 229-232 
    ISSN: 1588-2837
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Оба энантиомера транс-2,3-дифенил-фосфинометил-норборнена-(5), синтезированные двумя независимыми путями, были исследованы как лиганды в асимметрическом гидрировании α-ацетамидокоричной кислоты в присутствии родия(I). Небольшое изменение структкры лигандов приводит к заметному изменению активности каталитической системы.
    Notes: Abstract Both enantiomers of trans-2,3-diphenylphosphinomethyl-norbornene-(5), prepared by two independent synthetic routes, were used as ligands in the asymmetric hydrogenation of α-acetamidocinnamic acid in the presence of rhodium(I). Small variations in the ligand structure have a remarkable influence on the activity of the catalytic system.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 535-539 
    ISSN: 0899-0042
    Keywords: asymmetric hydrogenation ; non-coded amino acids ; enantioselectivity ; dipeptides ; diastereoselectivity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantiomers of Propranolol, Pindolol, and Carazolol, well-known β-blockers, have been used to prepare cationic aminophosphine phosphinite rhodium complexes. Propraphos-Rh and Pindophos-Rh are very efficient catalysts in the asymmetric hydrogenation of N-Boc-protected unusual dehydroamino acid derivatives. Carazolol-Rh is less suitable in both activity and enantioselectivity. Under the same conditions, N-Boc-protected dehydrodipeptides are hydrogenated with diastereoselectivities between 70 and 90% de. Chirality 10:535-539, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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