The invention relates to the technical field of
organic synthesis, and discloses a synthesis method of 2-cyano-5-fluorobenzyl
bromide, which comprises the following steps: mixing a compound I with
sulfuric acid, adding
potassium bromate, reacting, adding water, layering, distilling and purifying to obtain a compound II; mixing the compound II, cuprous
cyanide and DMF, carrying out
reflux reaction under stirring, cooling, adding water, extracting and filtering with
ethyl acetate, layering, washing with water, desolventizing, and recrystallizing and purifying with
methanol to obtain a compound III; mixing the compound III,
tetrahydrofuran, water and
methanol, dropwise adding a
mixed solution of
potassium borohydride, water and
methanol while stirring, adding water, layering, extracting, desolventizing, cooling to separate out a
solid, and filtering to obtain a compound IV; and mixing the compound IV, DCM and DMF, dropwise adding
boron tribromide in batches while stirring, adding water, layering, desolventizing, cooling to separate out a
solid, and filtering to obtain the 2-cyano-5-fluorobenzyl
bromide. The method is reasonable in design
route, short in synthesis
route, high in
safety coefficient and suitable for industrial production.