Process for the preparation of solifenacin
A process for the preparation of (1S)-QR)-I-azabicyclo[2.2.2.]oct-3-yl 3,4-dihydro-1-phenyl-2(1H)-isoquinoline carboxylate by reacting (1S)-alkyl 1-phenyl-1,2,3,4-tetrahydro-2-isoquinoline carboxylate with 3-(R)-quinuclidol in an inert solvent, where a primary alkyl ester of the carboxylate whose alkyl length is C 1 -C 4 is used and the reaction is catalyzed by a non-nucleophilic base.
1. A process for the preparation of (1S)-(3R)-1-azabicyclo[2.2.2.]oct-3-yl 3,4-dihydro-1-phenyl-2(1H)-isoquinoline carboxylate by reacting (1S)-alkyl-1-phenyl-1,2,3,4-tetrahydro-2-isoquinoline carboxylate with 3-(R)-quinuclidol in an inert solvent, wherein a primary alkyl ester of the carboxylate whose alkyl length is C 1 -C 4 is used and the reaction is catalyzed by a non-nucleophilic base selected from the group consisting of potassium tert-butanolate and sodium tert-butanolate, wherein the reaction is conducted in toluene at a temperature of the reaction mixture of 90° C. to 120° C., using 3-(R)-quinuclidol in a 0% to 50% molar excess with respect to (1S)-alkyl 1-phenyl-1,2,3,4-tetrahydro-2-isoquinoline carboxylate, and using 0% to 50% mol of the catalyst with respect to (1S)-alkyl 1-phenyl-1,2,3,4-tetrahydro-2-isoquinoline carboxylate.
2. The process as claimed in claim 1 , wherein the molar amount of the catalyst is lower than the molar excess of 3-(R)-quinuclidol with respect to (1S)-alkyl 1-phenyl-1,2,3,4-tetrahydro-2-isoquinoline carboxylate.
3. The process as claimed in claim 1 , wherein the primary alkyl ester is selected from the group of (1S)-alkyl 1-phenyl-1,2,3,4-tetrahydro-2-isoquinoline carboxylates.