Asymmetric synthesis and determination of the absolute configuration of FK584, an agent for the treatment of overactive detrusor

FK584(-)-N-tert-butyl-4,4-diphenyl-2-cyclopentenylamine hydrochloride, (-)-4-HCl], a potential candidate for the treatment of overactive detrusor, was synthesized in a 4-step approach starting with Sharpless oxidation of cyclopentenol 6 (kinetic resolution). This epoxidation is a rare case in that the empirical rule does not work. Regio- and stereoselective introduction of tert-butylamine to the obtained epoxycyclopentanol 5 and subsequent conversion of the resulting diol to an olefin completed the synthesis. The absolute configuration of FK584 was determined to be S by X-ray crystallographic analysis of the salt of S-(+)-mandelic acid.