Positive‐ion mass spectra and collision‐induced dissociation of some 2,3‐didehydro amino acids

The positive-ion mass spectra of a number of didehydro amino acids, ionized by electron impact and/or thermospray, and collision-induced dissociation spectra taken at collision energies of a few electron volts and keV have been performed on multiple quadrupole and reversed geometry sector instruments. Observed differences in the mass spectra and in the fragmentation patterns are explained in terms of different isomeric structures, different internal excitation energies and different ion transit times between the ion source and the collision cell. Molecular ions of unhydrated amino acids are efficiently formed both by electron impact and thermospray, whilst molecular ions of the hydrated compounds are formed more efficiently by the latter technique. The present investigation demonstrates that the use of different ionization techniques combined with mass spectrometry/mass spectrometry measurements at different collision energies yields a wealth of information relevant to structural characterization of this important class of molecules.

[1]  J. Bakos,et al.  Chiral sulphonated phosphines , 1989 .

[2]  D. Ajó,et al.  Crystal state conformation of a β,β' -disubstituted dehydroaminoacid derivative , 1988 .

[3]  D. Ajó,et al.  Crystal state conformation of aβ,β′-disubstituted dehydroaminoacid derivative , 1988 .

[4]  John A. Gladysz,et al.  Ein neuartiger heterodinuclearer Katalysator für die asymmetrische Hydrierung — ein Bisphosphido‐Ligand mit einem stereogenen Rheniumzentrum , 1987 .

[5]  B. Costisella,et al.  O.N‐bis(diphenylphosphino) derivatives of chiral trans‐ and cis‐2‐aminocyclohexanols: Synthesis and enantioselective behaviour as ligands in Rh‐based homogeneous hydrogenation catalysts , 1987 .

[6]  H. Parnes,et al.  Synthesis of 14C-labelled peptides by asymmetric reduction of dehydroamino acids. , 2009, International journal of peptide and protein research.

[7]  A. Mortreux,et al.  Synthèse d'aminophosphinephosphinites chiraux. Utilisation en réduction asymétrique catalytique , 1986 .

[8]  A. Mortreux,et al.  Hydrogenation asymetrique des dehydroaminoacides catalysee par des complexes rhodium-aminophosphine phosphinite. Influence de la structure des chelates , 1986 .

[9]  R. Selke,et al.  Phosphinites of carbohydrates as chiral ligands for asymmetric synthesis catalysed by complexes: Part II. Superiority of phenyl 4,6-O-(R)-benzylidene-2,3-O-bis(diphenylphosphino)-β-D-glucopyranoside for rhodium(I)-catalysed hydrogenation of amino acid precursors , 1986 .

[10]  R. Selke.  Phosphinites of carbohydrates as chiral ligands for asymmetric synthesis catalysed by complexes: Part III. Immobilization of cationic rhodium(I) chelates of phenyl 4,6-O-(R)-benzylidene-2,3-O-bis(diphenylphosphino)-β-D-glucopyranoside on cation exchangers for hydrogenation of dehydroamino acids , 1986 .

[11]  H. Brunner,et al.  Asymmetrische Katalysen, 31. Enantioselektive katalytische Reduktion von Dehydroaminosäuren mit Ameisensäure , 1986 .

[12]  M. Yamashita,,et al.  Homogeneous Asymmetric Hydrogenation Using a Chiral Phosphinite Derivative of Carbohydrates as Ligand , 1986 .

[13]  Y. Amrani.  Polyoxadiphosphines-1,2 chirales: synthses et applications en hydrognation asymtrique , 1985 .

[14]  R. Deschenaux,et al.  Transition-metal-catalyzed asymmetric organic synthesis via polymer-attached optically active phosphine ligands. XIII: Asymmetric hydrogenation with polymer catalysts containing primary and chiral secondary pendant alcohols , 1985 .

[15]  T. Yamagishi,et al.  Asymmetric Hydrogenation of Dehydroamino Acids and Dehydrodipeptides with Rhodium(I)-modified DIOP Catalysts , 1984 .

[16]  T. Yamagishi,et al.  Asymmetric Hydrogenation with Rhodium(I)–Chiral Diphosphinites. The Effect of the Dimethylamino Group of the Ligand on the Asymmetric Induction , 1984 .

[17]  I. Ojima.  Homogeneous asymmetric catalysis by means of chiral rhodium complexes , 1984 .

[18]  H. Brunner,et al.  Asymmetrische Katalysen, 11. Vorausberechnung von Enantioselektivitäten bei der Rh‐katalysierten Hydrierung von Aminosäure‐Vorläufern mit dem Ruch/Ugi‐Modell , 1983 .

[19]  Y. Shimohigashi,et al.  E/Z-Configurational assignment of dehydropeptides: Differential noe enhancement between the vinyl and amide protons of an α,β-dehydro amino acid derivative , 1982 .

[20]  A. G. Harrison,et al.  Stereochemical applications of mass spectrometry. II—Chemical ionization mass spectra of isomeric dicarboxylic acids and derivatives , 1980 .

[21]  R. P. Morgan,et al.  The MM-ZAB-2F double-focussing mass spectrometer and mike spectrometer , 1978 .