Mutasynthesis of Glycopeptide Antibiotics: Variations of Vancomycin's AB-Ring Amino Acid 3,5-Dihydroxyphenylglycine
作者:Stefan Weist、Claudia Kittel、Daniel Bischoff、Bojan Bister、Volker Pfeifer、Graeme J. Nicholson、Wolfgang Wohlleben、Roderich D. Süssmuth
DOI:10.1021/ja0499389
日期:2004.5.1
In the mutasynthetic approach, the DeltadpgA mutant of the vancomycin-typeglycopeptideantibiotic producer Amycolatopsis balhimycina, which is deficient in the synthesis of 3,5-dihydroxyphenylglycine (DPg), was supplemented with synthetic DPg analogues to obtain the corresponding modified glycopeptides. Sterically more demanding 3,5-disubstituted methoxy derivatives as well as monosubstituted DPg
Synthesis of [11C](−)-α,α-dideutero-phenylephrine for in vivo kinetic isotope studies
作者:R. B. Del Rosario、D. M. Wieland
DOI:10.1002/jlcr.2580360703
日期:1995.7
(−)-[11C]Phenylephrine and positron emission tomography could potentially be used to assess neuronal monoamine oxidase activity in the heart. Previous data for (−)-(11C]phenylephrine indicate that, although its retention and neuronal selectivity parallel that of the neuronal mapping agent (−)-[11C]hydroxyephedrine, its neuronal storage and clearance properties are quite different. In order to study the in vivo kinetics of (−)-[11C]phenylephrine in greater detail, the dideutero analog [11C]-(−)-α,α-dideutero-phenylephrine, 1, was synthesized by [11C]methylation of the precursor (−)-α,α-dideutero-m-octopamine. The key step in the procedure was BD3 reduction of the cyanohydrin derived from 3-hydroxybenzaldehyde. Deuterium incorporation at the alpha positions of m-octopamine was confirmed by NMR and mass spectroscopy of the deuterated product and by comparison of spectral data with undeuterated m-octopamine. (−)-α,α-Dideutero-m-octopamine was methylated with CF3SO311CH3 to give 1 suitable for animal and clinical studies.