A mixture of 3-(4-carboxy-benzyl)-7-chloro-4-oxo-1-phenyl-1,4-dihydroquinoline-2-carboxylic acid methyl ester (75 mg, 0.17 mmol), 3-amino-3,N,N-trimethyl-butyramide (24 mg, 0.17 mmol), BOP (150 mg, 0.34 mmol) and DIPEA (1 mL) in THF (15 mL) was stirred at RT overnight. The reaction mixture was partitioned between water and EtOAc, the organic layer separated, washed with water, dried over Na2SO4, filtered, and evaporated under reduced pressure. The crude residue was purified by preparative TLC (EtOAc/hexane, 75:25) to yield 7-chloro-3-[4-(2-dimethylcarbamoyl-1,1-dimethyl-ethylcarbamoyl)-benzyl]-4-oxo-1-phenyl-1,4-dihydro-quinoline-2-carboxylic acid methyl ester (71 mg) as a light brown foam. MS=574 [M+H]+; MP=84.1-95.5° C.
