Isobutyl chloroformate (0.261 g, 1.91 mmol) was dropwise added into an ice cold solution of 4-diethylamino-2-butynoic acid (0.456 g, 2.94 mmol) and N-methylmorpholine (0.294 g, 2.94 mmol) in 50 mL of tetrahydrofuran under N2. After stirring for 30 min, a solution of 0.5 g (1.47 mmol) of 6-amino-4-[(3-bromophenyl)amino]-3-quinolinecarbonitrile in 3 mL of pyridine was added dropwise and the mixture was stirred at 0° C. for 2 hr. The reaction was quenched with ice water, poured into saturated sodium bicarbonate and brine, and extracted with ethyl acetate. The ethyl acetate layer was concentrated and purified by thin-layer chromatography eluted with 15% methanol in ethyl acetate. The product was collected, and dried in vacuo to give 0.2 g (28.5%) of pale greenish yellow solid; ESMS m/z 476.2, 478.2 (M+H+); mp 133-135° C.
