To a solution of the compound of Step 3 (11.9 g, 26 mmol) in DMF (50 ml) was added methanol (11 ml, 290 mmol), diisopropylethylamine (6.7 g, 9.3 ml, 52 mmol), Pd(OAc)2 (0.58 g, 2.6 mmol), and 1,1′-bis(diphenylphosphino)ferrocene (1.44 g, 2.6 mmol) while bubbling argon through the mixture. This was then placed in a bomb reactor and purged three times with carbon monoxide and finally filled to 80 p.s.i. and heated to 70° C. for two hours. The reaction mixture was then poured into water (˜150 ml). Ethyl acetate (50 ml) was then added to the mixture and the aqueous phase was extracted six times. The combined organics were dried over sodium sulfate, filtered and concentrated. The crude material was allowed to dry on the hi-vac overnight and was then suspended in ethyl acetate. The undesired solids (methyl 8-(benzoyloxy)-5-oxo-5,6-dihydro-1,6-naphthyridine-7-carboxylate) that did not dissolve were collected by vacuum filtration and set aside. This was repeated twice. To the EtOAc solution was then added hexanes and a few drops of diethyl ether and the mixture was placed in a sonicator for 15 minutes which allowed solids to crystallize out of the solution. The solids were collected by vacuum filtration.
