Krizevski, R., Department of Aromatic Medicinal and Spice Crops, Newe Yaar Research Center, Agricultural Research Organization, Ramat Yishay, Israel, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Bar, E., Department of Aromatic Medicinal and Spice Crops, Newe Yaar Research Center, Agricultural Research Organization, Ramat Yishay, Israel
Dudai, N., Department of Aromatic Medicinal and Spice Crops, Newe Yaar Research Center, Agricultural Research Organization, Ramat Yishay, Israel
Levy, A., Department of Aromatic Medicinal and Spice Crops, Newe Yaar Research Center, Agricultural Research Organization, Ramat Yishay, Israel
Lewinsohn, E., Department of Aromatic Medicinal and Spice Crops, Newe Yaar Research Center, Agricultural Research Organization, Ramat Yishay, Israel
Sitrit, Y., Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Ben-Shabat, S., Department of Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, P. O. Box 653, Beer-Sheva 84105, Israel

Khat (Catha edulis Forsk.) is a perennial shrub whose young leaves are chewed for their psychostimulating and anorectic properties. The main active principles of khat are believed to be the phenylpropylamino alkaloids, primarily ()-cathinone [(S)-α-aminopropiophenone], (+)-cathine [(1S)(2S)- norpseudoephedrine], and ()-norephedrine [(1R)(2S)-norephedrine]. GC-MS analyses of young leaf extracts indicated the presence of two oxazolidine derivatives, 2,4-dimethyl-5-phenyloxazolidine and 4-methyl-2-(trans-1-pentenyl)-5- phenyloxazolidine. To ascertain the chemical identity of these compounds, we synthesized the putative compounds by condensation of norephedrine and acetaldehyde or trans-2-hexenal, respectively. Spectroscopic analyses (GC-MS, NMR) of the structures of these synthetic compounds showed them to have identical retention indexes and mass spectra characteristic to 2,4-dimethyl-5-phenyloxazolidine and 4-methyl-2-(trans-1-pentenyl)-5- phenyloxazolidine. Marked differences in the ratios between each of these two norephedrine oxazolidine derivatives and total phenylpropylamino alkaloids were found among thirteen different khat accessions further indicating polymorphism in alkaloid ratios and content in C. edulis. © Georg Thieme Verlag KG Stuttgart · New York.