To a mixture of 6-bromo-2,4-dichloro-3-phenylquinoline (363 mg, 1.03 mmol, Intermediate 1: step c) and 3-methylisoxazole-5-carbaldehyde (149 mg, 1.34 mmol) in THF (5 mL) at −78° C. was added n-BuLi (1.6 M in hexane, 0.707 mL, 1.13 mmol) dropwise. The mixture was stirred at −78° C. for 30 minutes, then moved to an ice bath and stirred for 30 minutes. The reaction was quenched by addition of saturated aqueous NH4Cl and then diluted with water. The mixture was extracted three times with EtOAc. The organic phase was dried (Na2SO4), filtered, and concentrated to afford the crude title compound which was used without further purification in the next reaction.
