6,7-bis-benzyloxy-1-biphenyl-4-ylmethyl-1,2,3,4-tetrahydro-isoquinoline hydrochloride (2) was prepared as follows: A stirred solution of 3 g (5.69 mmol) of 2-biphenyl-4-yl-N-[2-(3,4-bis-benzyloxy-phenyl)-ethyl]-acetamide and 5.6 ml (60 mmol) of phosphorus oxychloride in 25 ml of anhydrous acetonitrile was refluxed for 20 hours. The reaction solution was evaporated under reduced pressure and the residue was dissolved in 25 ml of methanol. To this stirred solution at 0° C., 2.27 g (60 mmol) of sodium borohydride was added portionwise. The stirred reaction mixture was allowed to reach room temperature overnight and then it was poured in 150 ml of 10% aqueous HCl solution. The precipitate was collected on a glass filter funnel, washed with water (3×50 ml), and air-dried overnight. The solid was recrystallized using ether/methanol mixture to provide 2.56 g (82%) of off-white crystals, mp 187-189° C.
