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The synthesis of BAY x 3702 was carried out as outlined: Chroman-2-carboxylic acid (I) was activated with thionyl chloride. The acid chloride (II) was treated with (S)-phenethylamine (III), affording a (1:1)-mixture of diastereomers. Fractional crystallization from ethanol gave the isomer (IV) in high diastereomerical purity; basic epimerization of the undesired diastereomer is feasible. The amide (IV) was reduced with diborane in THF, yielding the amine (V), which was submitted to catalytic hydrogenation over palladium-on-charcoal. The resulting optically pure (R)-2-aminomethyl chroman (VI) was alkylated with 4-bromobutyl saccharin (VII), which is easily available from saccharin sodium and 1,4-dibromobutane. BAY x 3702 was isolated as the hydrochloride salt. White, odorless crystals, m.p. 195 C, alpha(20,D) -42.2 (c 0.9, CHCl3). BAY x 3702 is soluble in water (2.1 g/100 ml), acetone (2.2 g/100 ml) and DMSO. The solid substance is heat-stable, nonhygroscopic and nonsensitive to light. It is unstable in alkaline medium (hydrolysis), sensitive to hydrolysis in aqueous dilute solutions/suspensions at weak acidic and neutral pH, but stable in acidic medium (pH less than or equal to 4). The UV spectrum shows maxima at 272 and 279 nm. BAY x 3702 can be assayed by HPLC.