Isobutyl chloroformate (0.214 g, 1.57 mmol) was dropwise added into an ice cold solution of 4-t-butyldimethylsiloxy-2-butynoic acid (0.336 g, 1.57 mmol) and N-methylmorpholine (0.19 g, 1.88 mmol) in 15 mL of tetrahydrofuan under N2. After stirring for 30 min, the reaction mixture was added dropwise into a solution of 0.4 g (1.18 mmol) of 6-amino-4-[(3-bromophenyl)amino]-3-quinolinecarbonitrile in 3 mL of tetrahydrofuran and 1.5 mL of pyridine and stirred at 0° C. for 1 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 column chromatography eluted with 60% ethyl acetate in hexane. The product was collected, and dried in vacuo to give 0.22 g (35%) of yellow solid;: mass spectrum (electrospray, m/e,): 535.1189 (M+.).
