Synthesis
(a) To a 500 mL autoclave was added 80 g (0.446 mol) of 4-nitrobenzo[b]thiophene, 4 g (0.05 g/g) of 5% palladium-carbon catalyst, and 320 mL of methanol. After the dosing was completed, the air in the kettle was replaced three times with nitrogen and then three times with hydrogen. Subsequently, hydrogen was charged into the kettle until the pressure reached 0.3 MPa, stirring was initiated, and the reaction mixture was heated to 50 °C and kept at this temperature for 6 h until the kettle no longer absorbed hydrogen. After the reaction was completed, stirring was continued for 30 minutes. After the reaction mixture was cooled to room temperature, the reaction solution was removed and filtered under nitrogen protection. The filtrate was concentrated under reduced pressure to a remaining volume of about 150 mL to give 60 g of compound (II) in 90% yield.
References
[1] Patent: CN106831739, 2017, A. Location in patent: Paragraph 0066-0067; 0073-0081; 0087- 0095
[2] Justus Liebigs Annalen der Chemie, 1937, vol. 527, p. 83,101
[3] Journal of the American Chemical Society, 1955, vol. 77, p. 5939,5943
