Following the procedure in J.Org. Chem. 1996, 61 (11), 3849-3862, methyl-4-formylbenzoate (0.821 g, 5.00 mmol) was dissolved in 1,2-dichloroethane (75 ml) at room temperature. N-methylaniline (0.542 ml, 5.00 mmol) was added followed by sodium triacetoxyborohydride (1.484 g, 7.00 mmol). The mixture was allowed to stir at room temperature overnight. The mixture was quenched with saturated sodium bicarbonate solution and extracted with diethyl ether. The organic extracts were dried over anhydrous sodium sulfate and concentrated en vacuo. The residue was purified by-flash chromatography on silica eluted with 4:1 hexane/acetone to give 1.097 g (85.9%) of a slightly yellow oil of 4-[(methyl-phenyl-amino)-methyl]-benzoic acid methyl ester. Reduction to {4-[(methyl-phenyl-amino)-methyl]-phenyl}-methanol, condensation with(R)-2-isocyanato-3-phenyl-propionate of formula 5 and hydrolysis as described for example in Example 1 Steps 2-4, yielded about 1.5 g of 2-{4-[(methyl-phenyl-amino)-methyl]-benzyloxycarbonylamino}-3-phenyl-propionic 169, mp. 69.6-70.1° C.
