Not a chemist, fyi
The 2 5 dimethoxy benzaldehyde is usually purchased, and from there you make the nitrostyrene with nitromethane and a catalyst, ethylaminediacetate works well, is believe methylamine can work too. Maybe phenethylamine, but idk.
The nitrostyrene is reduced to the phenethylamine, 2C-H. An amalgam works well here.
Then the 2C-H is brominated. Usually through bromine, bromine formed insitu with sodium bromide and concentrated h202 in DCM, or a brominating agent like N bromo succinimide.
Finally you form the preferred salt.
You should be able to Google 2cb synthesis with pictures and a guide on drugs forum might pop up. Erowid also helps, as does PIHKAL