63060-94-6Relevant articles and documents
Asymmetric Synthesis of N-Substituted α-Amino Esters from α-Ketoesters via Imine Reductase-Catalyzed Reductive Amination
Yao, Peiyuan,Marshall, James R.,Xu, Zefei,Lim, Jesmine,Charnock, Simon J.,Zhu, Dunming,Turner, Nicholas J.
supporting information, p. 8717 - 8721 (2021/03/16)
N-Substituted α-amino esters are widely used as chiral intermediates in a range of pharmaceuticals. Here we report the enantioselective biocatalyic synthesis of N-substituted α-amino esters through the direct reductive coupling of α-ketoesters and amines employing sequence diverse metagenomic imine reductases (IREDs). Both enantiomers of N-substituted α-amino esters were obtained with high conversion and excellent enantioselectivity under mild reaction conditions. In addition >20 different preparative scale transformations were performed highlighting the scalability of this system.
Effects of the central lanthanide ion crystal radius on the 15-MCCu II(N)pheHA-5 structure
Zaleski, Curtis M.,Lim, Choong-Sun,Cutland-Van Noord, Annabel D.,Kampf, Jeff W.,Pecoraro, Vincent L.
experimental part, p. 7707 - 7717 (2011/10/18)
Twenty crystal structures of the LnIII[15-MC CuII(N)pheHA-5]3+ complex, where pheHA = phenylalanine hydroxamic acid and where LnIII = YIII and La III-TmIII, except PmIII, with the nitrate and/or hydroxide anion are used to assess the effect of the central metal ion on the metallacrown structure. Each LnIII[15-MCCuII(N)pheHA- 5]3+ complex is amphiphilic with a hydrophobic side consisting of the phenyl groups of the pheHA ligand and a side without the aromatic residues. Three general structures are observed for the LnIII[15-MC CuII(N)pheHA-5]3+ complexes. In the Type 1 structures, the central metal ion does not bind a nitrate anion on the metallacrown's hydrophobic face, and two adjacent metallacrowns dimerize through their phenyl groups producing a hydrophobic compartment. In the Type 2 structures, the central metal ion binds a nitrate in a bidentate fashion on the hydrophobic face. There are two distinct types of Type 2 metallacrowns, designated A and B. Type 2A metallacrowns have a water molecule bound to the central metal ion on the hydrophilic face, while Type 2B metallacrowns have a monodentate nitrate ion bound on the hydrophilic face to the central metal ion. The Type 2 metallacrowns also dimerize via the phenyl groups to form a hydrophobic compartment. In Type 3 structures, the central metal ion binds a nitrate in a bidentate fashion on the hydrophobic side, but instead of forming dimers, the metallacrowns pack in a helical arrangement to give either P or M one-dimensional helices. Regardless of the type of metallacrown, the overall trend observed is that as the LnIII ion crystal radius increases, the metallacrown cavity radius also increases while the metallacrown becomes more planar. This conclusion is demonstrated by a decrease in the oxime oxygen distances to the oxime oxygen mean plane and a decrease in the ring Cu II distances to the CuII mean plane as the metallacrown cavity radius increases and the lanthanide crystal radius increases. In addition, a decrease in the Ooxime-CuII-N oxime-Ooxime torsion (dihedral) angles is also observed as the metallacrown cavity radius and the lanthanide crystal radius both increase. These observations help explain the thermodynamic preferences for Ln III ions within this class of metallacrowns and may be used to design compartments capable of binding guests in different orientations within chiral, soft solids.
Synthesis of novel morphinan peptides based on ethenoisomorphinans and enkephalin residues containing L- and D-phenylalanine; conformational analysis and preliminary pharmacology (Chemistry of opium alkaloids, Part XXXIII)
Cappon, J. J.,Lie, T. S.,Maat, L.
, p. 413 - 418 (2007/10/02)
The morphinan peptides N-(4,5α-epoxy-3,6-dihydroxy-17-methyl-6α,14α-ethenoisomorphinan-7α-carbonyl)-L-phenylalanine ethyl ester (4), N-(4,5α-epoxy-3,6-dihydroxy-17-methyl-3,6-dihydroxy-17-methyl-6α,14α-ethenoisomorphinan-7α-carbonyl)glycinyl>-L-phenylalanine ethyl ester (6) have been prepared from 4,5α-epoxy-3,5-dimethoxy-17-methyl-6α,14α-ethenoisomorphinan-7α-carboxylic acid (7) and the protected amino acids.The morphinan moiety was coupled to the peptide residue via the acid chloride of 7, after which the morphinan peptides were O-demethylated with the aid of hydrogen bromide in glacial acetic acid.The dipeptide N-glycinyl-L-phenylalanine ethyl ester was synthesized via the Excess Mixed Anhydride method (EMA).The new morphinan peptides have been characterized by 1H and 13C NMR spectroscopy.For conformational analysis, the relative stabilities of two possible hydrogen bonds around the C7-C20 bond have been calculated on a model compound 11, using molecular mechanics.
