17802-02-7

Light yellow crystalline

Step i: 2-chloro-6-fluoronitrobenzene (6.62 g, 37.7 mmol) and LiOH-H2O (6.33 g, 151 mmol) were dissolved in a mixed solvent of THF (45 mL) and water (65 mL), followed by the addition of 30% aqueous H2O2 solution (8.60 mL, 80.0 mmol). The resulting turbid solution was sealed and heated to 60°C with vigorous stirring. After 3 days of reaction, the dark orange mixture was cooled and half-saturated aqueous sodium thiosulfate solution (200 mL) was added and vigorously shaken in a split funnel. Subsequently, the mixture was acidified to pH < 3 with 1N HCl, extracted with EtOAc (400 mL + 100 mL) and washed with brine (400 mL). The organic phases were combined, dried with magnesium sulfate, filtered and concentrated to give a dark yellow oil containing a small amount of solid particles (unreacted feedstock) (aminophenol 10b, 6.37 g, 97% yield), which was used directly in the next step of the reaction.

[1] Patent: WO2009/62285, 2009, A1. Location in patent: Page/Page column 64
[2] Patent: WO2009/62308, 2009, A1. Location in patent: Page/Page column 73-74
[3] Patent: WO2009/62288, 2009, A1. Location in patent: Page/Page column 70-71
[4] Patent: WO2009/62289, 2009, A1. Location in patent: Page/Page column 77-78
[5] Patent: WO2018/37223, 2018, A1. Location in patent: Page/Page column 154