A mixture of (S)-methyl 5-cyclobutoxy-2-methyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-3,4-dihydroquinoline-1(2H)-carboxylate (0.080 g, 0.20 mmol), tert-butyl 4-(4-bromo-1H-imidazol-2-yl)piperidine-1-carboxylate (0.200 g, 0.61 mmol), sodium carbonate (0.45 g, 0.42 mmol), and [1,1′-bis(diphenylphosphino)ferrocene]dichloropalladium(II) dichloromethane adduct (0.010 g, 0.01 mmol) in 1,4-dioxane (10 mL) and water (3 mL) was stirred at 90° C. overnight. The reaction mixture was cooled to room temperature, filtered through a short pad of Celite, and concentrated under vacuum. The residue was purified via preparative thin layer chromatography (eluting with 1:1, ethyl acetate/petroleum ether) to afford (S)-methyl 6-(2-(1-(tert-butoxycarbonyl)piperidin-4-yl)-1H-imidazol-4-yl)-5-cyclobutoxy-2-methyl-3,4-dihydroquinoline-1(2H)-carboxylate (0.050 g, 48%) as a light yellow solid. MS (ESI, pos. ion) m/z 525 [M+H]+.
