Ethyl 2-((5-bromo-3-nitropyridin-2-yl)oxy)acetate → 7-bromo-1H,2H,3H-pyrido[2,3-b][1,4]oxazin-2-one

Temperature

2.5 °C

In a 500 mL round-bottomed flask was added ethyl 2-(5-bromo-3-nitropyridin-2-yloxy)acetate (5.2 g, 17.04 mmol) in hydrochloric acid, 37% (50 mL) to give a yellow suspension. The mixture was cooled to 0-5° C. followed by the portion wise addition of tin powder (10.1168 g, 85 mmol). Caution must be taken during the addition as it is very exothermic. The mixture was stirred at room temperature for a further 30 minutes after the addition. The reaction mixture was heated to 80° C. under a nitrogen atmosphere for 3 hours. The reaction mixture was diluted with water (250 mL). The precipitate was filtered, washed with water (200 mL) and diethyl ether (200 mL) and dried until constant weight to give the title compound (3.2 g, 82%). 1H NMR (500 MHz, d6-DMSO): 10.41 (2H, s), 7.88 (2H, s), 7.34 (2H, s), 4.85 (2H, s).

1. customto give a yellow suspension
2. additionCaution must be taken during the addition as it
3. additionafter the addition
4. temperatureThe reaction mixture was heated to 80° C. under a nitrogen atmosphere for 3 hours
5. filtrationThe precipitate was filtered
6. washwashed with water (200 mL) and diethyl ether (200 mL)
7. customdried until constant weight

ORD record

ord-21586c868ae944b0b303aa9a29c52eae

Source dataset

uspto-grants-2015_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09221838B2