6-Methoxyisoquinoline synthesis: Using benzaldehyde as the starting material, m-methoxybenzaldehyde is obtained through nitration, reduction, diazotization, hydrolysis and methylation, and 3-methoxybenzaldehyde is obtained through condensation with nitromethane Shiff base and reduction of aluminum hydride -p-Phenylethylamine. The Pictet-Spengler reaction of 3-methoxyl-p-phenylethylamine and 40% aqueous formaldehyde produces 6-methoxyl-1,2,3,4-tetrahydroisoquinoline, and then obtains the target compound in dehydrogenation 6-Methoxyisoquinoline.