| Abstract
| - The development of density functional theory (DFT) methods for the calculation of vibrational circulardichroism (VCD), electronic circular dichroism (ECD), and transparent spectral region optical rotation(OR) has revolutionized the determination of the absolute configurations (ACs) of chiral molecules usingthese chiroptical properties. We report the first concerted application of DFT calculations of VCD, ECD,and OR to the determination of the AC of a natural product whose AC was previously undetermined.The natural product is the alkaloid schizozygine, isolated from Schizozygia caffaeoides. Comparison ofDFT calculations of the VCD, ECD, and OR of schizozygine to experimental data leads, for each chiropticaltechnique, to the AC 2R,7S,20S,21S for the naturally occurring (+)-schizozygine. Three other alkaloids,schizogaline, schizogamine, and 6,7-dehydro-19β-hydroxyschizozygine, have also been isolated from S.caffaeoides and shown to have structures closely related to schizozygine. Assuming a common biosyntheticpathway, their ACs are defined by that of schizozygine.
|
