Under nitrogen protection,Add 357.6g m-dibromobenzene (99%, 1.5mol) into a 500mL reaction flask,26.1g o-bromoaniline (99%, 0.15mol),0.084g palladium(II) acetate (99%, 0.375mmol),0.18g 2-dicyclohexylphosphine-2,4,6-triisopropylbiphenyl (99%, 0.375mmol),58.2g sodium tert-butoxide (99%, 0.6mol),After feeding,Warm up to 130°C,Stirring speed 600rpm,Incubate for 24hr,After the reaction,Vacuum distillation to recover unreacted m-dibromobenzene,Add water and ethyl acetate to extract the residue,The organic layer was desolvated to obtain the crude product which was crystallized in ethanol to obtain 34.3 g of 4-BroMo-9H-carbazole.The content is 99.6% and the yield is 92.5%.