Coumarin derivative and preparation method thereof

The preparation method comprises the following steps: under the protection of nitrogen, adding magnetons into a double-neck round-bottom flask, adding a condensing tube, and adding a brominated substrate 1, bis (tri-tert-butylphosphine) palladium (0), toluene, triethylamine and an olefin compound 2; then sealing the reaction bottle and placing the reaction bottle in an oil bath at 90 DEG C; after the reaction is completed (through TLC monitoring, about 12 minutes), cooling a reaction mixture to room temperature, adding a NaHCO3 aqueous solution, and then stirring for 5 minutes; transferring by using ethyl acetate to pass through a silica gel short column to remove insoluble solids, and washing by using ethyl acetate; diluting the filtrate with ethyl acetate, extracting with water for 3 times, and extracting with saturated sodium chloride for 1 time; drying the combined organic layer by using anhydrous Na2SO4; carrying out wet-process sample loading and column chromatography purification, so as to obtain a com