合成路线1

The benzyl-protected 2-(2-hydroxyethyl)phenol (I) was brominated in HOAc to give (II). Lithiation of aryl bromide (II) followed by in situ condensation of the resulting organolithium derivative (III) with diethyl oxalate under -95 C furnished the keto ester (IV). Subsequent ketone reduction by NaBH4 afforded hydroxy ester (V), which was further hydrolyzed to the mandelic acid derivative (VI). The condensation of racemic acid (VI) with (S)-2-amino-7-hydroxytetraline (VII) gave rise to a diastereomeric mixture of hydroxy amides from which the desired (S,R)-diastereoisomer (VIII) was isolated by column chromatography. Reduction of the amide function of (VIII) using borane-dimethyl sulfide complex yielded the amino alcohol (IX). Alkylation of the phenolic hydroxyl group of (IX) with 2-bromo-N,N-dimethylacetamide (X) provided the corresponding (aryloxy)acetamide (XI). Then, hydrogenolysis of the benzyl protecting groups over Pd/C furnished the target compound, which was finally isolated as the corresponding sulfate salt.