The product of Example 385E (90 mg, 0.17 mmol), O-benzotriazol-1-yl-N,N,N′,N′-tetramethyluronium tetrafluoroborate [TBTU] (60 mg, 0.19 mmol) and ethyl 2-amino-2-phenylpropanoate (39 mg., 0.20 mmol) in DMSO (0.9 mL) was reacted with N,N-diisopropylethylamine (0.060 mL, 0.34 mmol) dropwise at room temperature then stirred at room temperature for 18 hours under N2. The mixture was poured into water (10 mL) with stirring. The resulting precipitate was extracted with ethyl acetate (50 mL) and the organic layer was washed with water (3×), saturated aqueous NaHCO3, then brine, dried over MgSO4, and concentrated. The residue was purified by silica gel chromatography (ethyl acetate:chloroform 4:1) to give the title compound as a pale yellow amorphous solid (93 mg, 78%).
