To a methanol (5 ml) solution of 2-amino-5-chloro-α-(2-tert-butoxycarbonylaminomethylphenyl)benzyl alcohol (0.5 g) were added trimethyl acetaldehyde (132 mg) and acetic acid (92 mg). The mixture was stirred for 10 minutes at room temperature, to which was added sodium cyano borohydride (97 mg), followed by stirring for one hour at room temperature. To the reaction mixture was added acetic acid ethyl ester (50 ml). The mixture was washed with water and dried over anhydrous Na2SO4. The solvent was then distilled off. The residue was purified by means of a silica gel column chromatography to give the object 5-chloro-α-(2-tert-butoxycarbonylaminomethylphenyl)-2-neopentylaminobenzyl alcohol (0.61 g) as a colorless oily product.
