Patent ID: 7335793

Claim:
A process for the preparation of tolterodine or a pharmaceutically acceptable salt thereof, comprising: A) reacting a compound of formula (II) in which when X is —CH 2 — then R is —N (isopropyl) 2 ; or when X is ═CO then R is —N (isopropyl) 2 or —OR 1 , wherein R 1 is an aryl or a straight or branched C 1 -C 6 alkyl group, optionally substituted with phenyl; with an acidic agent; or B) reacting a compound of formula (III) wherein Y is a group able to provide a benzylic carbocation and Z is hydrogen or Y and Z, taken together, complete a double bond; and X and R are as defined above, with p-cresol and an acidic agent; to obtain, respectively, when in a compound of formula (II) or (III) a) X is —CH 2 — and R is —N(isopropyl) 2 , a tolterodine free base of formula (I) or when b) X is ═CO and R is —N(isopropyl) 2 , a compound of formula (III) which by reduction yields the tolterodine free base; or when c) X is ═CO and R is a —OR 1 group wherein R 1 is as defined above, a compound of formula (IV) wherein R 1 is as defined above, which is converted to the tolterodine free base by reductive amination; or conversion of the tolterodine free base to a pharmaceutically acceptable salt thereof.