6-(3-ethylureido)-4-(4-(trifluoromethyl)thiazol-2-yl)pyridin-3-ylboronic acid (Intermediate 9, 0.350 g, 0.97 mmol) and (S)-ethyl 6-bromo-1-(1-(2-morpholinoethyl)piperidin-3-yl)-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylate (Intermediate 34, 0.480 g, 0.97 mmol) were taken up in dioxane (4 mL), Cs2CO3 (0.633 g, 1.94 mmol) in water (1.000 mL) was added followed by Pd(PPh3)4 (0.112 g, 0.10 mmol). The reaction mixture was heated to 100° C. for 2 h, then 2 ml of 2N LiOH were added and stirred at 100° C. for an additional 30 min. The reaction mixture was cooled to room temperature and solvent evaporated. The resulting residue was taken back up in DMSO (2 ml) and filtered. DMSO solution was purified on an ISCO C18 column using water and acetonitrile. (S)-6-(6-(3-ethylureido)-4-(4-(trifluoromethyl)thiazol-2-yl)pyridin-3-yl)-1-(1-(2-morpholinoethyl)piperidin-3-yl)-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid (0.080 g, 12%) is recovered as a pale yellow solid.
