Sodium Hydroxide → 7-Methyl-1H-pyrido[2,3-b][1,4]oxazin-2(3H)-one

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Reaction Steps

In a 250 ml round flask, (5-methyl-3-nitro-pyridin-2-yloxy)-acetic acid methyl ester (5.47 g, 23.9 mmol) and tin tetrachloride (18.1 g, 95.6 mmol) were dissolved in 24 ml of concentrated hydrochloric acid, and then stirred at 800 for 1 hour. The reaction mixture was cooled to room temperature, neutralized with 10% NaOH solution, and extracted with ethyl acetate. The combined organic layer was washed with water and saturated saline solution, dried over anhydrous sodium sulfate (Na2SO4), filtered and evaporated under reduced pressure. The residue was purified by column chromatography on silica eluting with a solvent of dichloromethane:methanol=19:1. The resulting solid was recrystallized from dichloromethane/methanol/tetrahydrofuran to obtain 7-methyl-1H-pyrido[2,3-b][1,4]oxazin-2-one as pale-brown solid (2.65 g, 67%).

Provenance & Evidence