- Synthesis, Crystal Structure and Conformation of the Cyclic Dipeptide cyclo(-L-Seryl-L-seryl-)
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The synthesis, spectral data and X-ray structure determination of the cyclic dipeptide cyclo(-L-Ser-L-Ser-), C6H10N2O4, are reported.The compound was obtained by intramolecular aminolysis of two serine residues bridged via esteric bonds by a hydrocarbon chain.IR, CD and 1H NMR spectra are discussed in order to determine the salient features of the structure in solution.Crystals are orthorhombic, space group P212121, with cell dimensions a=11.096(2), b=7.787(1), c=8.538(1) Angstroem; R=0.053 for 784 observed reflections.The diketopiperazine ring (DKP) is nearly planar.Intermolecular hydrogen bonds connect the DKP rings in spirals parallel to the axis.
- Fava, Giovanna Gasparri,Belicchi, Marisa Ferrari,Marchelli, Rosangela,Dossena, Arnaldo
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- Bio-based epoxy resin precursor containing cyclic amide structure, and preparation method and application thereof
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The invention discloses a bio-based epoxy resin precursor containing a cyclic amide structure, and also discloses a preparation method and application of the bio-based epoxy resin precursor containingthe cyclic amide structure. The preparation method comp
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Paragraph 0050-0051
(2019/03/10)
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- Hydrogen-bond-induced hysteresis in the compression/relaxation of monolayer films
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Two stereoisomers of surfactants were synthesized in which a diketopiperazine ring was inserted between a hydrocarbon chain (of variable length) and an anionic headgroup. It was found (by HPLC, conductivity, surface tension, and diffusion NMR) that these compounds have low solubilities in water, remarkably high Krafft temperatures, and low critical micelle concentrations. Of particular interest were the pressure/area isotherms of insoluble monolayers of nonionic analogues of the amphiphiles. These isotherms showed an unprecedented hysteresis but only during the first compression/relaxation cycle. Additional cycles were normal in that they lacked the original hysteresis. These results were attributed to diketopiperazine rings that initially lie flat on the water surface at the air/water interface. Compression flips the diketopiperazine rings so that they now reside roughly perpendicular to the interface in a stable hydrogen-bonded orientation where the rings occupy far less space. Copyright
- Sorrells, Jennifer L.,Menger, Fredric M.
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supporting information; experimental part
p. 10072 - 10073
(2009/02/04)
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- Hexafluoroacetone as Protecting Group and Activating Reagent in Amino Acid and Peptide Chemistry, XI. A New Simple Preparative Access to 2,5-Dioxopiperazines and 2,5-Dioxomorpholines
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2,5-Dioxopiperazines with symmetrical as well as unsymmetrical substituent pattern can be obtained via 2,2-bis(trifluoromethyl)-1,3-oxazolidin-5-ones, and 2,5-dioxomorpholines via 2,2-bis(trifluoromethyl)-1,3-dioxolan-4-ones, respectively. Keywords: Hexafluoroacetone; α-Amino acids; α-Hydroxy acids; 2,2-Bis(trifluoromethyl)-1,3-oxazolidin-5-ones; 2,2-Bis(trifluoromethyl)-1,3-dioxolan-4-ones; 2,5-Dioxopiperazines; 2,5-Dioxomorpholines.
- Burger, K.,Rudolph, M.,Windeisen, E.,Worku, A.,Fehn, S.
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p. 453 - 464
(2007/10/02)
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- Facile Synthesis of Cyclic Dipeptides and Detection of Racemization
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Several cyclic dipeptides were synthesized by refluxing methanolic solution of dipeptide methyl esters in high yield and purity.Cyclic dipeptides prepared by the Fischer method, the Nitecki method, and the present methanol-reflux method were compared with
- Ueda, Toshihisa,Saito, Morinobu,Kato, Tetsuo,Izumiya, Nobuo
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p. 568 - 572
(2007/10/02)
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