合成路线1

The cyclization of 1,3-diphenylthiourea (I) with Br2 and HBr in water gives N-(benzothiazol-2-yl)-N-phenylamine (II), which is condensed with 2-chloropropionyl chloride (III) by means of AlCl3 in dichloromethane to yield the propiophenone (IV). The reaction of (IV) with dimethylamine in isopropanol affords the racemic alpha-(dimethylamino) propiophenone (V), which is optically resolved by means of (+)(D)-di-p-toluoyltartaric acid providing the (S)-enantiomer (VI) with a 80% ee. The reduction of (VI) with NaBH4 and NaOH in isopropanol gives the (S,S)-enantiomer (VII) with a 85% ee. Finally, this compound is condensed with CDI and imidazole to afford the target compound that is purified by crystallization in ethyl acetate up to a 99% ee.