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Pyroglutamic Acid (pyroglutamic + acid)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

ChemInform Abstract: Synthesis of Functionalized Pyroglutamic Acids.

CHEMINFORM, Issue 4 2009
Part 1.
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Cyclopeptides and Amides from Pseudostellaria heterophylla (Caryophyllaceae)

HELVETICA CHIMICA ACTA, Issue 10 2003
Ya-bin Yang
From the roots of Pseudostellaria heterophylla, three cyclopeptides and three amides were isolated, besides heterophyllin A and B. Their structures were determined as cyclo (Ala-Gly-Pro-Val-Tyr-) (heterophyllin J; 1), cyclo (Ala-Gly-Pro-Tyr-Leu-) (pseudostellarin A; 2), cyclo (Gly-Gly-Gly-Pro-Pro-Phe-Gly-Ile-) (pseudostellarin B; 3), methyl , -hydroxypyroglutamate (4), methyl pyroglutamate (5), and pyroglutamic acid (6) on the basis of spectral data, especially 2D-NMR data. Among them, compounds 1 and 4 are new compounds. [source]

N-Heterocyclic Carbene-Mediated Enantioselective Addition of Phenols to Unsymmetrical Alkylarylketenes

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2009
Carmen Concellón
Abstract Chiral N-heterocyclic carbenes (NHCs) mediate the enantioselective addition of 2-phenylphenol to unsymmetrical alkylarylketenes, delivering ,-alkyl-,-arylacetic acid derivatives with good levels of enantiocontrol (up to 84% ee). Enantiodivergent stereochemical outcomes are observed using 2-phenylphenol and benzhydrol in the NHC-promoted esterification reaction using a triazolium precatalyst derived from pyroglutamic acid, consistent with distinct mechanistic pathways operating within these processes. [source]

Characterization of ,- and ,-glutamyl dipeptides by negative ion collision-induced dissociation

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 2 2004
Alex G. Harrison
Abstract The low-energy CID mass spectra of the [M , H], ions of a variety of dipeptides containing glutamic acid have been obtained using cone-voltage collisional activation. Dipeptides with the ,-linkage, H-Glu(Xxx-OH)-OH, are readily distinguished from those with the ,-linkage, H-Glu-Xxx-OH, by the much more prominent elimination of H-Xxx-OH from the [M , H], ions of the former isomers, resulting in formation of m/z 128, presumably deprotonated pyroglutamic acid. Dipeptides with the reverse linkage, H-Xxx-Glu-OH, show distinctive fragmentation reactions of the [M , H], ions including enhanced elimination of CO2 and formation of deprotonated glutamic acid. Exchange of the labile hydrogens for deuterium has shown that there is considerable interchange of C-bonded hydrogens with labile (N- and O-bonded) hydrogens prior to most fragmentation reactions. All dipeptides show loss of H2O from [M , H],. MS3 studies show that the [M , H , H2O], ion derived from H-Glu-Gly-OH has the structure of deprotonated pyroglutamylglycine while the [M , H , H2O], ions derived from H-Glu(Gly-OH)-OH and H-Gly-Glu-OH show a different fragmentation behaviour indicating distinct structures for the fragment ions. Copyright © 2004 John Wiley & Sons, Ltd. [source]