Di-t-butyl dicarbonate (1.25 g) in t-butanol (15 ml) was added to a stirred solution of (R)-4-[2-(2-hydroxy-2-phenylethylamino)ethoxy]phenylacetic acid hydrochloride (2.0 g) in 1N aqueous sodium hydroxide (30 ml). The reaction mixture was stirred for 90 minutes at 20° C. The solvent was removed under reduced pressure. Water (20 ml) was added to the residue and the solution was acidified with 2N aqueous citric acid. The product was extracted into 5% methanol in dichloromethane (5×20 ml). The extracts were dried and the solvent removed under reduced pressure to yield N-t-butoxycarbonyl-(R)-[4-[2-(2-hydroxy-2-phenylethylamino)ethoxy]phenylacetic acid as a glass (13 g); [α]25D =-6.2° (c=1.0 in methanol).
