Zobrazeno 1 - 10
of 63
pro vyhledávání: '"H.‐J. Kreuzfeld"'
Autor:
H.‐J. Kreuzfeld, M. Beller
Publikováno v:
Catalysis from A to Z.
Publikováno v:
Amino Acids. 22:325-331
N-[(Z)-N-Benzoyl- or N-boc-(2-fluorophenyl)dehydroalanyl]-(R)- or (S)-phenyl-alanines 1,2,5 and 6 were hydrogenated in the presence of chiral and achiral rhodium complexes. The optical induction is compared to the results obtained using the correspon
Publikováno v:
Tetrahedron Letters. 41:3821-3824
The first transition metal-catalysed racemisation of N-acyl α-amino acids, which is of importance for kinetic resolution processes, is described. Enantiomerically pure N-acyl α-amino acids were efficiently racemised under mild conditions using vari
Publikováno v:
Amino Acids. 16:21-27
(Z)-alpha-[(Benzyloxy)- or (tert.-butyloxy)carbonylamino]-beta (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 r
Publikováno v:
Chirality. 10:535-539
Publikováno v:
Tetrahedron: Asymmetry. 7:1011-1018
The enantiomers of PINDOPHOS, the aminophosphine phosphinite derivative of the commercial s-blocker Pindolol, were prepared and used as ligands in the rhodium catalyzed asymmetric hydrogenation of non-proteinogenic amino acid precursors. The isolated
Publikováno v:
Tetrahedron: Asymmetry. 7:117-125
( Z )-2- N -Acylamino-3-pyridyl-acrylic acids and their esters were prepared by partially known procedures and hydrogenated in the presence of HBF 4 to the corresponding optically active 2- N -acetyl-(or benzoyl-)-3-(3- or 4-pyridyl)-alanines or anal
Autor:
Chr Döbler, Ch. Fischer, Manfred Michalik, H.-J. Kreuzfeld, S. Taudien, Ute Schmidt, H.W. Krause
Publikováno v:
Chirality. 8:173-188
Substituted N-Cbz and N-Boc protected arylamino acrylic acids and esters have been prepared and used in asymmetric hydrogenations catalyzed by PROPRAPHOSRh. Stereoselectivities > 90% ee could be achieved, the rate of which is dependent on the positio
Publikováno v:
Tetrahedron: Asymmetry. 6:3039-3045
α-Chymotrypsin (EC 3.4.21.1) was used for catalyzing the reaction of various N α -unprotected non-coded phenylalanine ester derivatives with H-Leu-NH 2 and H-Arg-NH 2 in frozen aqueous solution at −15 °C. Compared with reactions at room temperat
Publikováno v:
Tetrahedron: Asymmetry. 6:385-388
Crystalline and in situ formed Rh-complexes from (1 R ,3 R ,5 R )-O,N-bis-(diphenylphosphino)-3-hydroxymethyl-2-azabicyclo-[3.3.0.]-octane and from the all ( S )-enantiomer have been prepared and used in model asymmetric hydrogenations. The catalysts