Determination of the absolute configuration of flexible molecules by ab initio ORD calculations: a case study with cytoxazones and isocytoxazones.
Ab initio calculations of the optical rotatory power of the natural cytokine modulator cytoxazone 1 and its trans-diastereomer 2, as well as the structural isomers cis-3 and trans-4 isocytoxazones, have been performed at four different wavelengths (589, 546, 435, and 405 nm) by Density Functional Theory. The calculation of ORD curves provides a reliable method for the assignment of absolute configuration of these conformationally flexible molecules. The absolute configurations of isocytoxazones has been established as (+)-(4R,5S)-cis-3 and (+)-(4S,5S)-trans-4.
Giorgio
Egidio
E
Dipartimento di Chimica, Università della Basilicata, Via N. Sauro 85, 85100 Potenza, Italy.
Roje
Marin
M
Tanaka
Katsunori
K
Hamersak
Zdenko
Z
Sunjic
Vitomir
V
Nakanishi
Koji
K
Rosini
Carlo
C
Berova
Nina
N
D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010080:Oxazoles / Q000737:chemistry*; D013057:Spectrum Analysis
D010080:Oxazoles; C117832:cytoxazone