The present invention relates to a synthesis method of 6-methyl-4-bromo-
isoquinoline. The synthesis method comprises the following steps: using amino
acetaldehyde dimethyl acetal and p-tolualdehyde asraw materials, and carrying out a reaction for forming 2,2-methyl-N-(4-methoxy phenyl alkenyl)
ethylamine; then adding methyl chloroacetate and
trimethyl phosphite to obtain 2,2-dimethoxyethyl((dimethoxyphosphoryl)(p-methylphenyl)methyl)
ethyl carbamate; further adding
titanium tetrachloride for a reaction, after the reaction traced by a TLC method is completed, further adding a 2N
sodium hydroxidewater solution for reaction, then adding diatomite, carrying out stirring and suction
filtration, carrying out extraction on the water phase and the
filter cake with
ethyl acetate, carrying out
drying and rotary evaporateion, and carrying out
column chromatography purification by using a sufficient amount of
silica gel columns of 100-200 meshes to obtain 6-methyl
isoquinoline; and adding the 6-methyl
isoquinoline into
carbon tetrachloride, then adding N-bromo-
succinimide, carrying out heating and refluxing for 2-5 hours, concentrating the reaction mixture, carrying out
column chromatography with
silica gel columns of 100-200 meshes, using
petroleum ether PE and
ethyl acetate EA as eluants, and carrying out recrystallization with excess
petroleum ether to obtain the final product 4-bromo-6-methyl-isoquinoline. The method has the advantages of clear steps, less waste, high yield,
raw material conservation and easy operation.