Lithium hydroxide (168 mg, 1.76 mmol) in water (1.7 ml) is added to a solution of 4-[8-(3-methylsulfanyl-phenyl)-[1,7]naphthyridin-6-yl]-cyclohexanecarboxylic acid ethyl ester (650 mg, 1.6 mmol) in THF (3.2 ml) under argon. Methanol is added to maintain solution (4 ml) and the mixture is stirred at room temperature for 5 hours. The mixture is evaporated to dryness then partitioned between ethyl acetate and water. The aqueous layer is acidified to pH 2 then extracted into ethylacetate and dried over magnesium sulfate, Evaporation gives a green gum which is reevaporated from methanol then DCM/diethylether to give a yellow/green foam. The foam is triturated with 3:1 hexane:diethyl ether, 2:1 hexane:diethylether, ethylacetate/hexane/ether mixtures and finally 5:1 diethylether:ethanol to yield an off-white solid. This is then recrystallised from ethanol to yield the title compound. M.p 177.6-178.2° C., MS (AP+) 379.05
