Process for the preparation of N,N-diisopropyl-3-(2-hydroxy-5-methylphenyl)-3-phenyl-propaneamine

A process for the preparation of racemic tolterodine of the formula

• and the pharmaceutically acceptable salts thereof, comprising:
• substitution of the sulfonyloxy group of the compound of the formula
• in which
• R represents C1-C6 alkyl, CH2—Ar, SiR′3,
• in which Ar represents optionally substituted aryl and each R′ may mutually independently be linear or branched alkyl or optionally substituted aryl, or acyl and
• R″ represents C1-C6 alkyl or optionally substituted aryl,
• with N,N-diisopropylamine in a solvent comprising an ionic liquid to yield the tertiary amine of the formula
• in which R has the above-stated meanings,
• subsequent deprotection of the OR group to yield racemic tolterodine of the formula
• and optionally,
• salification thereof with a pharmaceutically acceptable acid.