PREPARATIVE CHROMATOGRAPHIC ENANTIOSEPARATION OF PUTATIVE MELATONIN RECEPTOR AGENTS, USING CELLULOSE CHIRAL STATIONARY PHASES

In order to obtain milligram amounts of the enantiomers of two tetrahydronaphthalenic derivatives 1 and 2, to be tested for binding to the melatonin sites, preparative HPLC was set up with a mobile phase consisting of n-hexane-alcohol and a silica-based cellulose tris-3,5-dimethylphenylcarbamate (Chiralcel OD-H), or tris-methylbenzoate (Chiralcel OJ) using isocratic conditions and multiple repetitive injections. The preparative separation was optimized by adjusting the sample size from a scale-up of the analytical method. The purity obtained were sufficient for a first screen of their biochemical affinity. A reversal of the enantiomeric elution order by the change-over of the carbamate type phase (Chiralcel OD-H) towards the benzoate type phase (Chiralcel OJ) was observed. The optical rotation and the circular dichroism spectra of the single enantiomers were determined after separation and their absolute configuration.