To N-(tert-butoxycarbonyl)glycine (527 mg, 3.01 mmol) in dry CH2Cl2 (5 mL) under argon were added PYBOP (1.65 g, 3.16 mmol), 1-amino-7-benzyloxynaphthalene, as described above in Step J, (750 mg, 3.01 mmol), and N,N-diisopropylethylamine (0.55 mL, 3.16 mmol). The reaction mixture was stirred for 18 hrs, then partitioned between CH2Cl2 (200 mL) and 10% aqueous citric acid (50 mL). The organic layer was dried over Na2SO4, filtered, and concentrated in vacuo. The crude product was sufficiently pure for use in the next reaction.
