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Robert J. Young - One of the best experts on this subject based on the ideXlab platform.

  • Flash vacuum pyrolysis of stabilised phosphorus ylides. Part 17. Preparation of aliphatic amino acid derived γ-alkoxycarbonylamino-β-oxo ylides and pyrolysis to give α,β-acetylenic γ-amino acid and GABA analogues
    Journal of the Chemical Society Perkin Transactions 1, 2002
    Co-Authors: R. Alan Aitken, Nazira Karodia, Tracy Massil, Robert J. Young
    Abstract:

    A series of eleven α-aminoacyl stabilised phosphorus ylides 9–19 have been prepared by condensation of N-alkoxycarbonyl protected amino acids with Ph3PCHCO2Et using a carbodiimide Peptide Coupling Reagent. Upon flash vacuum pyrolysis at 600 °C, these undergo extrusion of Ph3PO to give the corresponding α,β-acetylenic γ-amino esters 21–29, 33 and 34 in moderate yield. In two cases the terminal alkynes 30 and 31 are also formed. The β-aminoacyl ylide 20 from β-alanine similarly gives the α,β-acetylenic δ-amino ester 35 upon pyrolysis. Regioselective addition of HBr to the triple bond of one acetylenic ester 25 was observed giving a mixture of E and Z α-bromoacrylates 36. Hydrogenation of the N-Cbz acetylenic esters 21–23 and 33 results in N-deprotection and hydrogenation of the triple bond to afford the chiral GABA analogues 37–40 in 70 –>95% ee as determined by 19F NMR of their Mosher amides. Fully assigned 13C NMR spectra of all the ylides and acetylenic ester derivatives are presented.

Young R.j. - One of the best experts on this subject based on the ideXlab platform.

R. Alan Aitken - One of the best experts on this subject based on the ideXlab platform.

  • Flash vacuum pyrolysis of stabilised phosphorus ylides. Part 17. Preparation of aliphatic amino acid derived γ-alkoxycarbonylamino-β-oxo ylides and pyrolysis to give α,β-acetylenic γ-amino acid and GABA analogues
    Journal of the Chemical Society Perkin Transactions 1, 2002
    Co-Authors: R. Alan Aitken, Nazira Karodia, Tracy Massil, Robert J. Young
    Abstract:

    A series of eleven α-aminoacyl stabilised phosphorus ylides 9–19 have been prepared by condensation of N-alkoxycarbonyl protected amino acids with Ph3PCHCO2Et using a carbodiimide Peptide Coupling Reagent. Upon flash vacuum pyrolysis at 600 °C, these undergo extrusion of Ph3PO to give the corresponding α,β-acetylenic γ-amino esters 21–29, 33 and 34 in moderate yield. In two cases the terminal alkynes 30 and 31 are also formed. The β-aminoacyl ylide 20 from β-alanine similarly gives the α,β-acetylenic δ-amino ester 35 upon pyrolysis. Regioselective addition of HBr to the triple bond of one acetylenic ester 25 was observed giving a mixture of E and Z α-bromoacrylates 36. Hydrogenation of the N-Cbz acetylenic esters 21–23 and 33 results in N-deprotection and hydrogenation of the triple bond to afford the chiral GABA analogues 37–40 in 70 –>95% ee as determined by 19F NMR of their Mosher amides. Fully assigned 13C NMR spectra of all the ylides and acetylenic ester derivatives are presented.

Youngah Kim - One of the best experts on this subject based on the ideXlab platform.

  • recent development of Peptide Coupling Reagents in organic synthesis
    Tetrahedron, 2004
    Co-Authors: Soyeop Han, Youngah Kim
    Abstract:

    In recent years, Peptide Coupling reactions have been significantly advanced in accord with the development of new Peptide Coupling Reagents in organic synthesis. Even though a number of valuable reviews have been published in this area, the development of new Peptide Coupling Reagents has been steadily accelerated in the past few years. Moreover, tremendously expanded applications have been possible to new and broad synthetic challenges. This report focuses on the major advances in Coupling Reagents that have had a great impact in the field. Among many, Coupling Reagents responsible for the formation of azide, mixed anhydride, and acid halide intermediates have gained substantial popularity in Peptide Coupling reactions. DCC as a Peptide-Coupling Reagent has particularly attracted organic chemists in their synthesis of complex molecules. Moreover, the development of onium-type Coupling Reagents has made the incorporation of non-coded or sterically hindered amino acids including N-methylated and a,a-dialkylated amino acids smoothly into the corresponding Peptides possible. In a typical Peptide Coupling reaction, the carboxylic acid moiety of the amino acid I is first activated by an appropriate Peptide Coupling Reagent, and then reacted with the amine moiety of the amino acid II to produce a desired Peptide as illustrated in Scheme 1.

Karodia Nazira - One of the best experts on this subject based on the ideXlab platform.