Lithium Hydroxide → 4-(4-tert-Butoxycarbonylamino-phenylsulfanyl)-3-(7-tert-butyl-pyrido[2,3-d]pyrimidin-4-ylamino)-benzoic acid

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Reaction Conditions

Reaction Steps

To a solution of 4-(4-tert-butoxycarbonylamino-phenylsulfanyl)-3-(7-tert-butyl-pyrido[2,3-d]pyrimidin-4-ylamino)-benzoic acid methyl ester (0.53 g, 0.1 mmol) in a mixture of THF (9 mL) and MeOH (3 mL) was added aqueous LiOH [prepared from LiOH monohydrate (0.21 g, 5.0 mmol) and H2O (3 mL)] dropwise at room temperature. The mixture was stirred at 50° C. for 4 hours, and then evaporated. The aqueous mixture was diluted with H2O, washed with AcOEt, and then carefully acidified to pH 4-5 with 10% HCl at 5° C. under stirring. The resulting solid was collected by filtration, washed with H2O, and dried at 60° C. overnight under reduced pressure to give the title compound as yellow powder (0.53 g, 99%).

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