6-[(tert-Butoxycarbonyl)amino]nicotinic acid

Synthesis

Step 5. Synthesis of 6-((tert-butoxycarbonyl)amino)nicotinic acid. Methyl 6-((tert-butoxycarbonyl)amino)nicotinate (50 g, 19 mmol) was dissolved in methanol (50 mL) and 1N NaOH aqueous solution (40 mL, 40 mmol) was added. The reaction mixture was stirred at room temperature for 20 hours, followed by heating to 60°C for 2 hours. After completion of the reaction, the solution was cooled and methanol was removed under vacuum. To the remaining solution, 3N HCl was slowly added and the pH was adjusted to 3. A white solid precipitate was precipitated. The solid product was collected by filtration, washed with water and dried to give 6-((tert-butoxycarbonyl)amino)nicotinic acid 23 g (89% yield) as a white solid.

References

[1] Patent: WO2010/130708, 2010, A1. Location in patent: Page/Page column 72
[2] Patent: WO2010/144345, 2010, A1. Location in patent: Page/Page column 65
[3] Patent: WO2016/33445, 2016, A1. Location in patent: Paragraph 0297
[4] Patent: WO2009/36996, 2009, A2. Location in patent: Page/Page column 92
[5] Patent: EP3305785, 2018, A1. Location in patent: Paragraph 0233