Methanol → 1-(phenylsulfonyl)-2,3-dihydro-1H-pyrido[2,3-b][1,4]oxazine-7-carboxylic acid

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Reaction Steps

To a solution of methyl 1-(phenylsulfonyl)-2,3-dihydro-1H-pyrido[2,3-b][1,4]oxazine-7-carboxylate (270 mg, 0.808 mmol) in THF (10 mL)/MeOH (10 mL)/water (10 mL) was added lithium hydroxide (38.7 mg, 1.615 mmol). The reaction was stirred at room temperature for 16 hours. LCMS analysis of the reaction mixture identified the molecular ion corresponding to product. The reaction mixture was concentrated in vacuo to remove the organic solvents. The aqueous layer was acidified with 1N aqueous HCl (10 mL), which resulted in a white precipitate formation. The aqueous layer was extracted with EtOAc (2×30 mL). The combined organics were dried over anhydrous Na2SO4 and concentrated in vacuo to provide 1-(phenylsulfonyl)-2,3-dihydro-1H-pyrido[2,3-b][1,4]oxazine-7-carboxylic acid (230 mg, 0.718 mmol, 89% yield) as an off-white solid that was used without further purification. LCMS (+ESI) m/z=321.0 [M+H]+.

Provenance & Evidence