Epimerization and stereochemistry of avoparcin.
نویسندگان
چکیده
منابع مشابه
Epimerization and stereochemistry of avoparcin.
The epimerization of avoparcin entities is discussed in some detail. The absolute stereochemistry of avoparcin is now known since the N-methyl terminal amino acid of the aglycone has been isolated and shown to exhibit negative optical rotation and hence has the R-configuration. The same amino acid has been isolated from an epimerized solution of avoparcin and found to have positive rotation and...
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In recent reports (I ) the term racemization is used inappropriately. It is stated in both reports that Lisoleucine racemizes to D-alloisoleucine. This reaction is epimerization, not racemization. Racemization of L-iSOleucine results in the formation of DLisoleucine. As stated in Eliel (2): "'racemization is the process of producing a racemic modification starting with one of the pure enantiome...
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Dirithromycin (3) isomerizes upon dissolution in different solvents. From X-ray analysis of V-T 108, an analogue of dirithromycin, and comparative 1H and 13C NMR, and MS data, the isomer of dirithromycin was confirmed to be the C-16-(S)-epimer. The ratio of the two epimers at equilibrium conditions was approximately 8:2 (R/S) in methanol at room temperature.
متن کاملComponents and degradation compounds of the avoparcin complex.
The isolation and characterization of many of the components of the avoparcin complex are described. A number of mild degradations products from this complex are similarly treated. Conditions for the analytical and preparative HPLC resolution of these materials are outlined.
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A computer-readable dictionary for protein structure refinement is presented. The dictionary is based on the set of interatomic bonds and bond angles previously derived from small-molecule structures by Engh & Huber [Acta Cryst. (1991), A47, 392-400]. The internal inconsistency of the set is discussed. Some preliminary results derived from several protein structures refined at atomic resolution...
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ژورنال
عنوان ژورنال: The Journal of Antibiotics
سال: 1983
ISSN: 0021-8820,1881-1469
DOI: 10.7164/antibiotics.36.1683