w/ more greener route ; coupling reaction using :
TCDI reagent
TBDMSCl (for alcohol protection)(optional)
3-(dimethylamino)benzene-1-thiol = (3-Aminophenol + formaldehyde + STAB or Formic acid Eschweiler–Clarke reaction or Me2SO4) + (Lawesson reagent for 3-(dimethylamino)benzene-1-thiol)
Dimethylamine HCl or freebase 2M in THF
triethylamine(base)
CH3I or CH3Br or CH3Cl
Sodium tetrafluoroborate
Directly from R'COOH w/ :
1. Deep Eutectic Solvents (DES)
or
2. Coupling Reaction (EDC.HCl or CDI pyBOP...)