To a suspension of sodium hydride (3.58 g, 0.089 mol) in DMF (150 ml) at 0° C. was added a solution of 2-cyanoacetamide (3.48 g, 0.041 mol) and (E)-tert-butyl(1-(4-(3-(dimethylamino)-2-phenylacryloyl)phenyl)cyclobutyl)carbamate (15 g, 0.0357 mol) in methanol (5.5 ml) and DMF (150 ml). The resulting mixture was heated at 40° C. for 16 h. After cooled down to room temperature, the mixture was added to a solution of acetic (50 ml) in water (300 ml) slowly. The resulting precipitate was filtered and the filter cake was partitioned between water (250 ml) and dichloromethane (150 ml). The layers were separated and the aqueous phase extracted into dichloromethane (150 ml). The combined organic phases were washed with water (200 ml) and brine (150 ml), dried over Na2SO4, filtered and concentrated to dryness under reduced pressure to give the title compound as a yellow solid (14.6 g, 93%). LCMS (Method A): RT=6.59 min, M+1=442. 1H NMR (500 MHz, CDCl3): 7.89 (1H, s), 7.37-7.32 (2H, m), 7.22-7.16 (5H, m), 7.03-6.98 (2H, m), 2.50-2.37 (4H, m), 2.06-1.97 (1H, m), 1.82-1.77 (1H, m), 1.45-1.05 (9H, br).
