2 research outputs found
Monosaccharides as Potential Chiral Probes for the Determination of the Absolute Configuration of Secondary Alcohols
Herein, a new method for the elucidation
of the absolute configuration
of chiral secondary alcohols is proposed. This method is an alternative
for a widely used approach reported by Mosher and Dale and similar
methods that are based on the <sup>1</sup>H NMR shift (δ) changes
of protons that are attached to the substituents of the oxymethine
carbon atom. The presented method is not based on tracking the chemical
shift changes and utilizes stereochemically defined monosaccharides
as chiral probes. A secondary alcohol is glycosylated, and the resulting
glycoside is subjected to NMR studies. The observation of dipolar
couplings between the protons of the monosaccharide moiety and the
protons of the secondary alcohol moiety via the NOESY/ROESY spectra
enables the determination of the absolute configuration of the oxymethine
carbon atom
Data from: Intramolecular transformation of an antifungal antibiotic nystatin A1 into its isomer, iso-nystatin A1. Structural and molecular modeling studies
Nystatin A<sub>1</sub>, a polyene macrolide antifungal antibiotic, in a slightly basic or acidic solution undergoes an intramolecular transformation, yielding a structural isomer, the translactonisation product, <i>iso</i>-nystatin A<sub>1</sub> with lactone ring diminished by two carbon atoms. Structural evidence is provided by advanced NMR and MS studies. Molecular dynamics simulations and quantum mechanics calculations gave the insight into the course and mechanism of the transformation and its effect on the conformation of the subject molecule.<br