A process for preparing substituted pyrrolidine compounds, including (5)-2-{l-[2- (2,3-dihydrobenzofuran-5-yl)ethyl]-3-pyrrolidinyl}-2,2-diphenylacetamide hydrobromide, commonly known in the art as darifenacin, comprising reacting a pyrrolidine compound with a benzofuran derivative in the presence of a phase-transfer catalyst.
CLAM(S): 1. A process for preparing a compound of formula (I): <img class="EMIRef" id="14031677-00170001" /> or a pharmaceutically acceptable salt thereof, wherein R<1> is selected from the group consisting Of-CONH2 and -CN; R<2> is selected from the group consisting of -CH2- or -C=O; R<3> and R<4> are each hydrogen, or taken together form a double bond between the carbon atoms to which they are bonded, comprising reacting a compound of formula (II): <img class="EMIRef" id="14031677-00170002" /> or a salt or solvate thereof, wherein R<1> is defined as above, with a compound of formula (III): <img class="EMIRef" id="14031677-00170003" /> or solvate thereof, wherein R<2>, R<3>, and R<4> are defined as above; and Z is a leaving group, in the presence of an organic solvent, a phase-transfer catalyst, a base, and optionally water. 2. A process according to claim 1, wherein R<1> is -CONH2. 3. A process according to claim 1, wherein R<1> is -CN. 4. A process according to claim 1, wherein R<2> is -CH2-. 5. A process according to claim 1, wherein R<2> is -C=O. 6. A process according to claim 1, wherein R<3> and R<4> are each hydrogen. 7. A process according to claim 1 , wherein R<3> and R<4> taken together form a double bond between the carbon atoms to which they are bonded. 8. A process according to claim 3, wherein R<2> is -CH2- and R<3> and R<4> are each hydrogen. 9. A process according to claim 5, wherein R<1> is -CONH2 and R<3> and R<4> are each hydrogen. 10. A process according to claim 7, wherein R<1> is -CONH2 and R<2> is -CH2-. 11. A process according to claim 8, further comprising converting the -CN of the compound of formula (I) to -CONH2. 12. A process according to claim 9, further comprising converting the -C=O of the compound of formula (I) to -CH2-. 13. A process according to claim 10, further comprising converting the double bond of the compound of formula (I) to a single bond. 14. A process according to claim 1, wherein the compound of formula (I) is (S)-2- { 1 -[2-(2,3-dihydrobenzofuran-5-yl)ethyl]-3-pyrrolidinyl} -2,2-diphenylacetamide or a pharmaceutically acceptable salt thereof. 15. A process according to claim 1 , wherein the compound of formula (I) is (S)-2- { 1 -[2-(2,3-dihydrobenzofuran-5-yl)ethyl]-3-pyrrolidinyl} -2,2-diphenylacetamide hydrobromide. 16. A process according to claim 1, wherein the organic solvent is selected from the group consisting of toluene, n-butanol, chlorobenzene, chloroform, cyclohexane, diethyl ether, diethylene glycol, ethyl acetate, heptane, hexane, methyl tert-butyl ether (MTBE), 2- methyltetrahydrofuran, methylethylketone (MEK), methylene chloride, N-Methyl-2- pyrrolidone (NMP), nitromethane, pentane, xylenes, and mixtures thereof. 17. A process according to claim 1, wherein the organic solvent is selected from the group consisting of toluene, 2-methyltetrahydrofuran, MEK, and mixtures thereof. 18. A process according to claim 1 , wherein the organic solvent is 2- methyltetrahydrofuran. 19. A process according to claim 1, wherein the phase-transfer catalyst is selected from the group consisting of quaternary ammonium salts, phosphonium salts, crown ethers, polyethylene glycols, and combinations thereof. 20. A process according to claim 1, wherein the phase-transfer catalyst is a quaternary ammonium salt. 21. A process according to claim 20, wherein the quaternary ammonium salt is a short-Chain alkyl quaternary ammonium salt. 22. A process according to claim 21, wherein the short-chain alkyl quaternary ammonium salt is methyltriethylammonium chloride. 23. A process according to claim 1, wherein the base is selected from the group consisting of alkali metal hydroxides and alkali metal carbonates. 24. A process according to claim 1, wherein the base is an alkali metal hydroxide. 25. A process according to claim 24, wherein the alkali metal hydroxide is selected from the group consisting of sodium hydroxide, calcium hydroxide, and potassium hydroxide. 26. A process according to claim 25, wherein the alkali metal hydroxide is potassium hydroxide. 27. A process according to claim 1, wherein Z is selected from the group consisting of halogens and sulfonate esters. 28. A process according to claim 27, wherein Z is halogen. 29. A process according to claim 28, wherein the halogen is bromide. 30. A process according to claim 1 , wherein water is present in an amount of from about 5% to about 60% by volume, based on the volume of the solvent. 31. A process according to claim 30, wherein water is present in an amount from about 10% to about 50%. 32. A process according to claim 31, wherein the water is present in an amount from about 11% to about 40%. 33. A process according to claim 1, wherein the phase-transfer catalyst is methyltriethylammonium chloride; the base is potassium hydroxide; Z is bromide; and water is present in an amount of about 11% to about 40% by volume, based on the volume of solvent. 34. A process for preparing a compound of formula (IV): <img class="EMIRef" id="14031677-00200001" /> comprising reacting the L-(+)-tartrate salt of a compound of formula (V): <img class="EMIRef" id="14031677-00200002" /> with a compound of formula (VI): <img class="EMIRef" id="14031677-00200003" /> in the presence of methyltriethylammonium chloride, potassium hydroxide, and optionally water. 35. A process according to claim 34, further comprising converting a compound of formula (IV) to the hydrobromide salt. 36. A process according to claim 34, further comprising the steps of a) reacting the compound of formula (IV) with a solution of hydrogen bromide to form a first mixture; b) concentrating the first mixture by distillation under reduced pressure to form a concentrate; c) adding acetone and diisopropylether to the concentrate to form a second mixture; and d) evaporating the second mixture under reduced pressure to yield the hydrobromide salt of the compound of formula (IV). 37. A process according to claim 34, further comprising the steps of a) reacting the compound of formula (YV) with a solution of hydrogen bromide, in the presence of 2-methyltetrahydrofuran and b) filtering the suspension to yield the hydrobromide salt of the compound of formula (IV). 38. A process according to claim 37, further comprising purifying the hydrobromide salt of the compound of formula (IV) by suspending the hydrobromide salt of the compound of formula (IV) in methanol and MEK and filtering the suspension, thereby obtaining purified hydrobromide salt of the compound of formula (IV). 39. A process according to claim 34, wherein water is present in an amount of from about 5% to about 60% by volume, based on the volume of solvent. 40. A process according to claim 39, wherein water is present in an amount of about 10% to about 50%. 41. A process according to claim 40, wherein water is present in an amount of from about 11% to about 40%.