p g m wuts protective groups in organic synthesis 2nd edition john wiley amp sons 1991 and the racemic tolterodine base i obtained for example by using concentrated refluxing hbr or refluxing mixtures thereof with acetic acid or by using alcl 3 or pbr 3 the racemic tolterodine base i may then be transformed into r tolterodine l tartrate ia again according to methods known from the literature for example as described u s pat no 5 382 600 in one particularly preferred embodiment of the process provided by the present invention the dihydrocoumarin ii is reduced by means of sodium borohydride in isopropanol at ambient temperature and the alcohol viii derived therefrom is isolated by crystallisation the alcohol viii is then subjected to derivatisation of the phenolic hydroxyl group which may be performed by benzylation by means of benzyl chloride in a biphasic water naoh and toluene reaction medium with the assistance of a phase transfer agent generally tetrabutylammonium bromide or by methylation with methyl iodide and sodium carbonate in acetone the resultant alcohol iv is then derivatised on the hydroxyl group by means of functionalisation with mesyl chloride or tosyl chloride in toluene in the presence of a base such as triethylamine the reaction gives rise to the compound v which is subjected to a substitution reaction with diisopropylamine in a refluxing ionic liquid for example n methyl n hexyl imidazolium tetrafluoroborate to obtain vi the compound vi is subsequently transformed into tolterodine by removal of the hydroxyl protection performed with hbr in a.