Zur Diastereoisomerie natürlicher und synthetischer α-Bisabolole/On the Diastereoisomerism of Natural and Synthetic α-Bisabolols

Abstract

Abstract The stereochemistry of α-bisabolol is discussed. The chiralities of the different α-bisabolols from Myoporum crassifolium, Populus balsamifera and Vanillosmopsis erythropappa are deduced from the absolute configuration of natural bisabolol from chamomile, which has to be considered as being (1′S,2S)-configurated according to most recent investigations. Based on this assumption, (1′S, 2R)-configuration has to be ascribed to (-)-α-bisabolol from Myoporum crassifolium, whereas (1′R,2R)-resp. (1′S,2S)-structure is present in (+)-α-bisabolol from Populus balsamifera and (-)-α-bisabolol from Vanillosmopsis erythropappa being therefore enantiomeric to the latter. Consequently, the (-)-α-bisabolols from Matricaria chamomilla and Vanillosmopsis erythropappa turn out to be identical in all respects. Synthetic α-bisabolols, however, featuring approximately equal amounts of all the four possible stereoisomers, differ not only optically but also in their stereochemical uniformity from natural α-bisabolols. By means of NMR spectrometric methods the identity of the native active agent can be established in chamomile specialities; as a consequence possible admixtures of synthetic racemates of α-bisabolol thus can be identified and quantified.