AbstractInvestigations on stereochemistry of indole alkaloids are important in elucidation of the biosynthesis of these substances. The use of chemical intercorrelation between the particular types of indole alkaloids is limited or, in some cases, made possible by their wide structural variety and their marked polycyclic character. An unequivocal route in this respect consists in determination of the absolute configuration by means of the anomalous X-ray diffraction for the particular group of indole alkaloids. However, such a type of structural analysis is rather laborious and is therefor mainly used in the case of key problems only. It is consequently suitable to correlate structurally similar alkaloids by means of physical and chemical methods, especially in examinations aiming to detect the corresponding enantiometric structures (if any). In this respect, the chiroptical methods prove as the most potent.
In our previous work, optical rotatory dispersion (ORD) and circular dichroism (CD) of some groups of indole alkaloids has been investigated, namely, of the yohimbane, eburane, and 5,16-cyclo-3,4-secocorynane group. the indolo [2,3-a] - quinolizidine derivatives, and the lysergic acid group. In the present work, we have extended our examination on the alkaloids derived from the parent ibogane skeleton.