To 4.0 mL of an N,N-dimethylformamide solution containing 0.15 g of tert-butyl(1-(2-(5-bromo-7-methoxy-2-oxoquinolin-1(2H)-yl)ethyl)piperidin-4-yl)(2,3-dihydro-1,4-benzodioxin-6-ylmethyl)carbamate, 39 μl of ethyl acrylate, 50 μL of triethylamine and 6.1 mg of bis(tri-tert-butylphosphine)palladium(0) were added and heated under nitrogen atmosphere at 90° C. for 1.5 hours. The reaction mixture was cooled to the room temperature, and the solvent was removed under reduced pressure. The residue thus obtained was purified by silica gel column chromatography [eluent; chloroform:methanol=20:1] to give 0.15 g of ethyl (2E)-3-(1-(2-(4-((tert-butoxycarbonyl)(2,3-dihydro-1,4-benzodioxin-6-ylmethyl)amino)piperidin-1-yl)ethyl)-7-methoxy-2-oxo-1,2-dihydroquinolin-5-yl)acrylate as a light brown foam.
