Direct optical resolution of vesamicol and a series of benzovesamicol analogues by high-performance liquid chromatography.

The direct optical resolution of the vesicular acetylcholine uptake inhibitors vesamicol and benzovesamicol and nine benzovesamicol analogues were performed by HPLC on a commercially available cellulose tris(3,5-di-methylphenyl carbamate) chiral stationary phase. Separation of each enantiomeric pair was optimized with respect to solvent strength and flow-rate, using mobile phase mixtures of hexane-2-propanol-diethylamine. The method has been successfully applied to the analysis of the optical purity of benzovesamicol intermediates and products, including (-)-5-[123I]iodobenzovesamicol which is currently undergoing clinical evaluation as a tracer for mapping central cholinergic neurons, and the purification of both antipodes of (+/-)-7-[125I]iodobenzovesamicol.