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

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%).

1. extractionextracted with ethyl acetate
2. washThe combined organic layer was washed with water and saturated saline solution
3. dry with materialdried over anhydrous sodium sulfate (Na2SO4)
4. filtrationfiltered
5. customevaporated under reduced pressure
6. customThe residue was purified by column chromatography on silica eluting with a solvent of dichloromethane
7. customThe resulting solid was recrystallized from dichloromethane/methanol/tetrahydrofuran

ORD record

ord-8a2cba98932a482b94b72f7dd096b068

Source dataset

uspto-grants-2013_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08394792B2