Yield:109210-15-3 93%

Reaction Conditions:

with bromine in dichloromethane at -10 - 0; for 2 h;

Steps:

1.1-1 Intermediate 1-a was synthesized according to Reaction Formula 1

Benzofuran 50 g (423 mmol) in a 1 L reactor,Add 500 mL of dichloromethane and stir.After cooling to -10° C., 67.7 g (423 mmol) of bromine was diluted with 100 mL of dichloromethane and added dropwise.The mixture was stirred at 0°C for 2 hours.After completion of the reaction, after adding an aqueous solution of sodium thiosulfate and stirring,It was extracted with ethyl acetate and H2O.After concentrating the organic layer under reduced pressure,Recrystallization from ethanol yielded 100 g of Intermediate 1-a.(Yield 93%)

References:

JP2020/83896,2020,A Location in patent:Paragraph 0108-0112