Into a solution of 4-({[4-(methoxycarbonyl)benzoyl]amino}methyl)benzoic acid (1.0 g, 3.19 mmol) and N-methyl morpholine (420 μL, 3.83 mmol) in anhydrous THF (25 mL) at 0° C. was added isobutyl chloroformate (455 μL, 3.51 mmol) then tert-butyl hydrazine carboxylate (1.12 mg, 7.66 mmol). After stirring at 0° C. for 1 hr and overnight at rt, the reaction mixture was quenched with HCl (1N, 25 mL). Extraction with EtOAc (2×25 mL), drying over MgSO4 and evaporation under vacuo gave a residue. Purification by flash chromatography (SiO2, EtOAc) gave the title compound (773 mg, 55%) as a white powder.
