To the crude solution from Step A was added methanol (125 ml, 5 ml/g cresol) and diisopropylamine (92 ml, 0.693 mol, 3 equiv). The mixture was then hydrogenated over 20 wt % Pd(OH)2/C wet (5.6 g, 10 wt % theory of the benzopyran-2-ol) at 110° C. under 586×103 Nm−2 (85 psi) hydrogen pressure. Reaction progress was monitored by HPLC (completion usually occurs between 16 and 24 h). Upon completion, the mixture was cooled, purged with nitrogen, filtered and washed with toluene (2×25 ml). The filtrate was then azeotroped with toluene to remove all methanol and diisopropylamine to end at a final volume corresponding to 10 ml/g cresol. The solution was then stirred at 50-60° C. and 37% HCl (19.3 ml, 0.231 mol, 1.0 equiv c.f cresol) was added resulting in the precipitation of racemic tolterodine hydrochloride. The suspension was cooled to 25° C. and stirred for 2 h, then filtered and washed with toluene (2×50 ml). Racemic tolterodine hydrochloride was then dried under vacuum at 50° C. Yield was 52.7 g, 63% from p-cresol with achiral purity of 97%.
