合成路线1

The synthesis of radiolabeled raloxifene has been reported: The esterification of 3,5-dibromo-4-hydroxybenzoic acid (I) with methanol/HCl gives the corresponding methyl ester (II), which is condensed with 1-(2-chloroethyl)piperidine (III) by means of K2CO3 in DMF yielding 3,5-dibromo-4-[2-(1-piperidyl)ethoxy]benzoic acid methyl ester (IV). The hydrolysis of (IV) with NaOH in methanol affords the corresponding free acid (V), which by treatment of SOCl2 in toluene is converted to the acyl chloride (VI). The Friedel-Crafts condensation of (VI) with 6-methoxy-2-(4-methoxyphenyl)benzo[b]thiophene (VII) by means of AlCl3 in dichloromethane gives [3,5-dibromo-4-[2-(1-piperidinyl)ethoxy]phenyl]-[6-methoxy-2-(4-methoxy phenyl)benzo[b]thien-3-yl]methanone (VIII), which is demethylated with AlCl3 and ethylmercaptane to dibromoraloxifene (IX). Finally, this compound is submitted to hydrogenolysis with tritium over Pd/C in methanol.