Synthesis
Step 1. Saccharin (10.0 g, 54.6 mmol) was slowly added to a 300 mL THF solution of LiAlH4 (2.24 g, 59.0 mmol) at 0 °C. The reaction mixture was stirred at 15 °C for 3 h in an inert atmosphere. Upon completion of the reaction, EtOAc (100 mL) was slowly added followed by 10% H2SO4 (100 mL). The organic layer was separated and washed with 100 mL of 5% sodium carbonate solution, dried over anhydrous sodium sulfate, filtered and concentrated to afford 1,2-dihydro-1,1-dioxo-1,2-benzisothiazole (4.4 g, 97%).
References
[1] Patent: WO2018/49324, 2018, A1. Location in patent: Page/Page column 25
[2] Organic Letters, 2014, vol. 16, # 6, p. 1550 - 1553
[3] Patent: WO2017/21805, 2017, A1. Location in patent: Page/Page column 174
[4] Patent: US2013/303524, 2013, A1. Location in patent: Paragraph 0268-0269
[5] Journal of Medicinal Chemistry, 2016, vol. 59, # 19, p. 8868 - 8878
