Rhod,
Sure, all details and results will be provided. Now, since a simple route to the trimethyl phosphate for methylation is on the horizon (uemura will try to make some this weekend), the idea is to follow:
1) vanillin -> 5-iodo-vanillin from United States Patent 4,465,864 (99% yield)
2) 5-iodo-vannillin -> syringaldehyde (95% yield, see your post above)
3) syringaldehyde -> 3,4,5 trimethoxybenzaldehyde (92% yield)
From:
https://www.thevespiary.org/rhodium/Rhodium/chemistry/me3po4.html
In an apparatus similar to Example 1, 15.2 g (0.083 mol) of syringaldehyde and 15.0 g (0.11 mol) of potassium carbonate were heated to 105°C under nitrogen and 15 ml (0.12 mol) of trimethyl phosphate were added over 10 minutes. The mixture was maintained at about 80° C. for 3 hours then cooled to 45° C. and quenched with 50 ml of H2 O. The tan solid which precipitated was collected, washed with 3×50 ml of water and dried to give 15 g (92%) of 3,4,5-trimethoxybenzaldehyde.
4) 3,4,5-trimethoxybenzaldehyde -> 3,4,5 trimethoxynitrostyrene (a la Slotta would give 50%+ yield)
5) 3,4,5 trimethoxynitrostyrene -> 3,4,5 trimethoxyphenylethylamine (a la sunlight, yield say 50%+)
and BINGO....... P.S. the most likely non-OTC chems needed for 1-5 are iodine, p2o5 and MeONa. For the last one foxy2 or Antocho digged out a patent for preparing sodiummethylate solutions.
Carpe Diem