908248-27-1

The general procedure for the synthesis of 2-amino-5-nitropyridin-3-ol using 6-nitrooxazolo[4,5-b]pyridin-2(3H)-one as starting material was as follows: to a solution of 6-nitrooxazolo[4,5-b]pyridin-2(3H)-one (124 mmol) in ethanol (100 mL), a solution of sodium hydroxide (500 mmol) in water (180 mL) was added. The reaction mixture was heated to reflux at 80°C for 3 hours. Upon completion of the reaction, the reaction was quenched with concentrated hydrochloric acid (40 mL), followed by adjusting the pH with 2 M sodium carbonate solution to 8. The precipitated solid was collected by filtration to afford the target product, 2-amino-5-nitropyridin-3-ol, in 86% yield and the product was a yellow solid.

[1] Patent: WO2009/23844, 2009, A2. Location in patent: Page/Page column 120-121
[2] Patent: WO2010/21797, 2010, A1. Location in patent: Page/Page column 85
[3] Patent: WO2010/24980, 2010, A1. Location in patent: Page/Page column 103; 104
[4] Patent: US2014/274926, 2014, A1. Location in patent: Paragraph 0529; 0530
[5] Patent: WO2015/115673, 2015, A1. Location in patent: Page/Page column 76-77