Stereoselective hydrogenation process for preparing cis-6-phenyl-5-[4-(2-pyrrolidin-1-yl-ethoxy)-phenyl]-2-methoxy-5,6,7,8-tetrahydronaphthalene hydrochloride

A process for preparing cis-6-phenyl-5-[4-(2-pyrrolidin-1-yl-ethoxy)-phenyl]-2-methoxy-5,6,7,8-tetrahydronaphthalene hydrochloride, wherein said cis-6-phenyl-5-[4-(2-pyrrolidin-1-yl-ethoxy)-phenyl]-2-methoxy-5,6,7,8-tetrahydronaphthalene hydrochloride contains less than about 5% of 1-{2-[4-(6-methoxy-2-phenyl-naphthalen-1-yl)-phenoxy]-ethyl}-pyrrolidine hydrochloride, the process comprising, in the following order, the steps of:

• (a) charging a hydrogenation reaction vessel with an appropriate hydrogenation catalyst and a solution of 1-{2-[4-(6-methoxy-2-phenyl-3,4-dihydronaphthalene-1-yl)phenoxy]ethyl}pyrrolidine hydrochloride in an appropriate solvent;
• (b) pressurizing the hydrogenation reaction vessel with hydrogen to a pressure of at least 20 psi to provide a hydrogenation reaction mixture;
• (c) heating the hydrogenation reaction mixture of step 2 at a temperature of at least 20° C. until 1% or less of the 1-{2-[4-(6-methoxy-2-phenyl-3,4-dihydronaphthalene-1-yl)phenoxy]ethyl}pyrrolidine hydrochloride remains to provide cis-6-phenyl-5-[4-(2-pyrrolidin-1-yl-ethoxy)-phenyl]-2-methoxy-5,6,7,8-tetrahydronaphthalene hydrochloride;
• (d) isolating the resulting cis-6-phenyl-5-[4-(2-pyrrolidin-1-yl-ethoxy)-phenyl]-2-methoxy-5,6,7,8-tetrahydronaphthalene hydrochloride;
• wherein the resulting cis-6-phenyl-5-[4-(2-pyrrolidin-1-yl-ethoxy)-phenyl]-2-methoxy-5,6,7,8-tetrahydronaphthalene hydrochloride contains less than about 2.5% of 1-{2-[4-(6-methoxy-2-phenyl-naphthalen-1-yl)-phenoxy]-ethyl}-pyrrolidine hydrochloride.