Calyxamides A and B, Cytotoxic Cyclic Peptides from the Marine Sponge <i>Discodermia calyx</i>
作者:Miki Kimura、Toshiyuki Wakimoto、Yoko Egami、Karen Co Tan、Yuji Ise、Ikuro Abe
DOI:10.1021/np2009187
日期:2012.2.24
thiazole moieties were isolated from the marinespongeDiscodermiacalyx collected near Shikine-jima Island, Japan. The structures of calyxamides A (1) and B (2), including the absolute configurations of all amino acids, were elucidated by spectroscopic analyses and degradation experiments. The structures are similar to keramamides F and G, previously isolated from Theonella sp. The analysis of the
Chiral Discrimination in the Liquid Phase: Excess Volumes of Binary Mixtures of Amino Acid Derivatives
作者:Luciano Lepori、Bernhard Koppenhoefer
DOI:10.1021/j100078a031
日期:1994.7
Volume changes on mixing the enantiomers of N-trifluoroacetylamino acid methyl esters (N-TFA-amino acid-OMe) were determined at 25 degrees C by means of a high-precision vibrating-tube densimeter. The excess molar volumes (V-E) for the racemic mixtures of N-TFA-Ala-OMe 1, N-TFA-Val-OMe 2, and N-TFA-Leu-OMe 3, were found as V-E = 0.0098, -0.0458, and 0.035 cm(3) mol(-1), respectively. For 2 and 3, these volumetric effects of discriminating interactions between enantiomers in the liquid phase are the largest ever observed.
(S)-2-CHLOROALKANOIC ACIDS OF HIGH ENANTIOMERIC PURITY FROM (S)-2-AMINO ACIDS: (S)-2-CHLOROPROPANOIC ACID
作者:Koppenhoefer, Bernhard、Schurig, Volker
DOI:10.15227/orgsyn.066.0151
日期:——
N-Trifluoracetyl-aminosäuren, XIX. Gaschromatographische Trennung von<i>N</i>-TFA-Dipeptid-methylestern
作者:Friedrich Weygand、Bruno Kolb、Axel Prox、Monohar A. Tilak、Ichiro Tomida