Synthesis
1. 4-Bromothiophenol (1.0 g, 5.3 mmol) was dissolved in anhydrous dimethylformamide (50 mL) and cooled to 0 °C under nitrogen protection.
2. Dry sodium hydride (153 mg, 6.4 mmol) was added in batches, and 2-bromopropane (0.60 mL, 6.4 mmol) was added after vigorous gas escape ceased.
3. The reaction mixture was stirred at room temperature overnight.
4. The reaction mixture was slowly poured into water (300 mL) and extracted with ethyl acetate (2 x 150 mL).
5. The organic layers were combined and washed sequentially with water (100 mL) and brine (100 mL).
6. Dry the organic layer with anhydrous sodium sulfate, filter and concentrate in vacuum.
7. The residue was purified by silica gel column chromatography using a hexane solution of 5% ethyl acetate as eluent to afford 1-bromo-4-isopropylthioalkyl benzene (1 g, 92% yield).
8. 1-Bromo-4-isopropylthioalkylbenzene (2.5 g, 10.8 mmol) was dissolved in anhydrous tetrahydrofuran (100 mL) and cooled to -78 °C. The mixture was then dissolved in anhydrous tetrahydrofuran (100 mL).
9. 2.5 M hexane solution of n-butyllithium (5.2 mL, 12.9 mmol) was added dropwise and the reaction mixture was warmed to -40 °C and stirred for 30 min.
10. The reaction mixture was cooled again to -78 °C, triisopropyl borate (7.4 mL, 32.4 mmol) was added and slowly warmed to room temperature.
11. 10% aqueous potassium hydroxide solution (96 mL, 172 mmol) was added and stirred overnight.
12. Slowly pour the reaction mixture into a mixture of concentrated hydrochloric acid and ice.
13. The aqueous phase was extracted with dichloromethane and the organic phase was dried over anhydrous sodium sulfate and concentrated in vacuo to give 1-bromo-4-(propan-2-ylsulfonylamino)benzene (1.9 g, 90% yield).
References
[1] Organic Letters, 2015, vol. 17, # 24, p. 6162 - 6165
[2] Patent: WO2004/9086, 2004, A1. Location in patent: Page/Page column 42-43
[3] Tetrahedron, 2004, vol. 60, # 17, p. 3915 - 3920
[4] Patent: WO2004/63179, 2004, A1. Location in patent: Page 48
[5] Patent: WO2014/146490, 2014, A1. Location in patent: Page/Page column 120
