Ethyl (6-bromo-2-nitropyridin-3-yloxy)acetate → 6-Bromo-2H-pyrido[3,2-B][1,4]oxazin-3(4H)-one

Temperature

77 °C

Ethyl (6-bromo-2-nitropyridin-3-yloxy)acetate (41 g, 0.132 mole) was dissolved in glacial AcOH (400 mL) and the solution was heated to 77° C. with mechanical stirring. Iron powder (50 g, 0.89 mole) was added portionwise over 2 hr, so that the temperature did not rise above 90° C. The mixture was mechanically stirred and heated at 77° C. for 10 hr then was cooled to room temperature and diluted with 1:4 EtOAc/CHCl3 (1 L). The mixture was filtered through a pad of celite® and the filtrate was concentrated in vacuo. The residue was purified by flash chromatography on silica gel (1 kg; 0-10% EtOAc/CHCl3) to afford the title compound (21.5 g, 70%): MS (ES) m/e 229 (M+H)+.

1. customdid not rise above 90° C
2. temperatureheated at 77° C. for 10 hr
3. temperaturethen was cooled to room temperature
4. filtrationThe mixture was filtered through a pad of celite®
5. concentrationthe filtrate was concentrated in vacuo
6. customThe residue was purified by flash chromatography on silica gel (1 kg; 0-10% EtOAc/CHCl3)

ORD record

ord-996e451e655c44979c633322572d88ec

Source dataset

uspto-grants-2009_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07618959B2