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4-Hydroxyproline

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Norikazu Nishino – One of the best experts on this subject based on the ideXlab platform.

  • epoxy amino acids produced from allylglycines intramolecularly cyclised to yield four stereoisomers of 4 hydroxyproline derivatives
    RSC Advances, 2014
    Co-Authors: Suvratha Krishnamurthy, Toru Arai, Kanae Nakanishi, Norikazu Nishino

    Abstract:

    Derivatives of 2-amino-4-pentenoic acid (allylglycine) were efficiently resolved using Subtilisin or acylase. The side-chain unsaturated bond of the enantiomerically pure amino acid with tert-butoxycarbonyl (Boc) protection was smoothly epoxidized with m-chloroperbenzoic acid. When the Boc protection of the amino group was removed, the amino group intramolecularly attacked the side-chain epoxide, generating compounds with five-membered rings: the 4-Hydroxyproline derivatives. Two diastereomeric products were formed through the cyclisation reaction, for example, (2S,4S)-4-Hydroxyproline benzyl ester (cis-8) and (2S,4R)-4-Hydroxyproline benzyl ester (trans-8) were formed from (2S)-amino acid with a side-chain epoxide. Compound (2S,4S)-4-Hydroxyproline benzyl ester (cis-8) was transformed to a lactone (cis-hydroxyproline lactone, 10) with the removal of benzyl alcohol. The cis-conformation was essential for the intramolecular ester exchange reaction; in fact, no lactone formation was observed for the trans isomer (trans-8). The separation of cis-hydroxyproline lactone and the trans-isomeric hydroxyproline benzyl ester was facile and clear, in contrast to the difficult separation of cis- and trans-hydroxyproline derivatives. Thus, two diastereomers of hydroxyproline derivatives for L-hydroxyproline and also for D-hydroxyproline were obtained, i.e., four diastereomers of hydroxyproline derivatives.

Daniel Seidel – One of the best experts on this subject based on the ideXlab platform.

  • decarboxylative formation of n alkyl pyrroles from 4 hydroxyproline
    ChemInform, 2011
    Co-Authors: Daniel J Coiro, Daniel Seidel

    Abstract:

    A new protocol for the synthesis of N-alkylated pyrroles and related indoles via microwave-accelerated decarboxylative condensation of corresponding N-heterocyclic carboxylic acid with carbonyl compounds is presented.

  • Decarboxylative Formation of N‐Alkyl Pyrroles from 4‐Hydroxyproline.
    ChemInform, 2011
    Co-Authors: Indubhusan Deb, Daniel J Coiro, Daniel Seidel

    Abstract:

    A new protocol for the synthesis of N-alkylated pyrroles and related indoles via microwave-accelerated decarboxylative condensation of corresponding N-heterocyclic carboxylic acid with carbonyl compounds is presented.

  • decarboxylative formation of n alkyl pyrroles from 4 hydroxyproline
    Chemical Communications, 2011
    Co-Authors: Daniel J Coiro, Daniel Seidel

    Abstract:

    N-Alkyl
    pyrroles are obtained in a single step from 4-Hydroxyproline and aldehydes in just 15 min under microwave irradiation.

Gerald Gübitz – One of the best experts on this subject based on the ideXlab platform.

  • Enantiorecognition of triiodothyronine and thyroxine enantiomers using different chiral selectors by HPLC and micro-HPLC.
    Journal of Biochemical and Biophysical Methods, 2008
    Co-Authors: Julia Koidl, Martin G. Schmid, Heike Hödl, Bianca Neubauer, Marlene Konrad, Sabine Petschauer, Gerald Gübitz

    Abstract:

    Abstract This paper deals with the chiral separation of triiodothyronine (T 3 ) and thyroxine (T 4 ) by HPLC and micro-HPLC. The separation of T 3 and T 4 is of great pharmaceutical and clinical interest, since the enantiomers exhibit different pharmacological activities. The HPLC measurements were performed on a chiral stationary ligand-exchange phase using l –4-Hydroxyproline bonded via 3-glycidoxypropyltrimethoxysilane to silica gel as a selector. Also a chiral teicoplanin (Chirobiotic ™®) phase was used. In micro-HPLC the chiral separation behaviour of l –4-Hydroxyproline, and of the macrocyclic antibiotics teicoplanin and teicoplanin aglycone was investigated for the enantioseparation of T 3 and T 4 . l –4-Hydroxyproline was bonded to 3 μm and the glycopeptide antibiotics were bonded to 3.5 μm silica gel and separations were accomplished by microbore HPLC columns (10 cm × 1 mm I.D.). With both techniques and all chiral selectors investigated T 3 and T 4 were baseline resolved. micro-HPLC was found to be superior to analytical HPLC with respect to low consumption of packing material, mobile phase and analyte.

  • Fast chiral separation by ligand-exchange HPLC using a dynamically coated monolithic column.
    Journal of Separation Science, 2006
    Co-Authors: Martin G. Schmid, Karin Schreiner, Daniela Reisinger, Gerald Gübitz

    Abstract:

    The preparation and application of dynamically coated ligand-exchange chromatography phases for enantioseparation is described. The phases were prepared by pumping a solution of N-decyl-L-4-Hydroxyproline, N-hexadecyl-L-4-Hydroxyproline, or N-2-hydroxydodecyl-L-4-Hydroxyproline through a commercially available monolithic RP-18 column. These coatings are stable against desorption for months at ambient temperature when aqueous mobile phases are used. The columns were applied to the chiral separation of amino acids, glycyl dipeptides and diastereomeric dipeptides, and tripeptides. The chiral selector can be removed or changed easily by washing the column with ACN or methanol. Ultrafast separations in the range of seconds were achieved using high flow rates.

  • Chiral separation of β-methyl-amino acids by ligand exchange using capillary electrophoresis and HPLC
    Journal of Pharmaceutical and Biomedical Analysis, 2001
    Co-Authors: Nina Grobuschek, Martin G. Schmid, Claudia Tuscher, M Ivanova, Gerald Gübitz

    Abstract:

    This paper deals with the chiral separation of optical isomers of β-methyl-amino acids by CE and HPLC using the principle of ligand-exchange. Capillary zone electrophoresis was carried out using Cu(II) complexes of l-4-Hydroxyproline (l-4-Hypro), N-(2-hydroxypropyl)-l-4-Hydroxyproline (HP-l-4-Hypro) and N-(2-hydroxyoctyl)-l-4-Hydroxyproline (HO-l-4-Hypro) as chiral selectors, added to the electrolyte. The HPLC separations were performed on a chiral stationary ligand-exchange chromatography phase containing l-4-Hypro chemically bonded to silica gel. With both techniques nearly all compounds investigated are baseline resolved using different background electrolytes and mobile phases, respectively.