Synthesis of (9<i>R</i>,12<i>S</i>)- and (9<i>S</i>,12<i>S</i>)-Cycloisodityrosine and Their <i>N</i>-Methyl Derivatives
作者:Dale L. Boger、Jiacheng Zhou、Robert M. Borzilleri、Seiji Nukui、Steven L. Castle
DOI:10.1021/jo961346o
日期:1997.4.1
Full details of the synthesis of (9R,12S)- and (9S,12S)-cycloisodityrosine and their N-methylderivatives are detailed based on an intramolecular nucleophilic aromatic substitution reaction for formation of the key biaryl ether with 14-membered ring macrocyclization. Their comparison with prior samples and the documentation of a facile C9 epimerization within the natural 9S series are described.
Complete Stereochemistry of Neamphamide A and Absolute Configuration of the β-Methoxytyrosine Residue in Papuamide B
作者:Naoya Oku、Ravi Krishnamoorthy、Alan G. Benson、Robert L. Ferguson、Mark A. Lipton、Lawrence R. Phillips、Kirk R. Gustafson、James B. McMahon
DOI:10.1021/jo0508853
日期:2005.8.1
[GRAPHICS]The absolute stereochemistry of the three unresolved structural components in neamphamide A (1) was determined to be (R)-beta-methoxy-L-tyrosine, (2R,3R,4S)-4-amino-7-guanidino-2,3-dihydroxyheptanoic acid, and (2R,3R,4R)-3-hydroxy-2,4,6-trimethylheptanoic acid. Stereochemical assignments were made by chemical degradation of 1, derivatization of the resulting products, and then spectroscopic and chromatographic comparison of the derivatives with synthetically prepared standards. Using the same analytical protocol developed for 1, the beta-methoxytyrosine residue in papuamide B (2) was found to be (R)-beta-methoxy-D-tyrosine. This represents a rare example of divergent stereochemistry in an unusual amino acid residue that is present in two closely related classes of peptides.
A Synthetic Route to β-Hydroxytyrosine-Derived Tetramic Acids: Total Synthesis of the Fungal Metabolite F-14329
作者:Sebastian Bruckner、Robert G. Haase、Rainer Schobert
DOI:10.1002/chem.201701259
日期:2017.4.27
derived from β‐hydroxytyrosine are synthetically challenging. The first route to this structural motif, based upon a condensation between a Meldrum's acid conjugate bearing the acyl side chain, and a β‐hydroxytyrosinate, N‐protected by an ortho‐nitrobenzyl group is presented. This group enables the Dieckmann cyclization of the resulting N‐(β‐ketoacyl)amino ester, after which it can be removed photolytically