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What is the Structure of Peptide Antibiotic Tü 1718 B? Previously Proposed Structure Disproved by Synthesis
Author(s) -
Postels HansThomas,
König Wilfried A.
Publication year - 1992
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.1992199201212
Subject(s) - conformational isomerism , chemistry , dipeptide , mass spectrum , stereochemistry , spectral line , natural product , nmr spectra database , peptide , nuclear magnetic resonance spectroscopy , crystallography , molecule , organic chemistry , biochemistry , ion , physics , astronomy
Two stereoisomers ( 1a and 1b ) of N ‐( L ‐valyl)‐2′,5‐dihydroxyhomoproline, the proposed structure of the dipeptide antibiotic Tü 1718 B, were synthesized by starting from natural (2 S ,4 R )‐hydroxyproline. The 1 H‐ and 13 C‐NMR spectra of 1a and 1b clearly differ from the corresponding spectra of the natural product. From both synthetic stereoisomers characteristic mass spectra were obtained after esterification and trifluoroacetylation. Isomer 1a is present as a mixture of two stable conformers, as indicated by peak splitting in the 1 H‐NMR spectra, which disappears at higher temperature, while 1b exits as a single conformer. Both synthetic stereoisomers are antibiotically inactive.