To a solution of N-(4-ethoxy-1,1-dioxo-1,2,5-thiadiazol-3-yl)-L-tyrosine tert-butyl ester from Step A (150 mg, 0.38 mmol) and the formate salt of 2-(3-methylphenylaminocarbonylamino)eth-1-ylamine from Step B (210 mg, 0.89 mmol) in ethanol (10 mL) was added triethylamine (133 mg, 1.44 mmol). The reaction was stirred at room temperature overnight. Solvent was removed under reduced pressure and the residue purified by flash column chromatography (silica, 5% MeOH in EtOAc)to give the title compound (130 mg, 91%)
