The general procedure for the synthesis of 1-bromo-3,4,5-trimethoxybenzene from methyl p-bromobenzoate and 2-(4-methoxyphenyl)-5,5-dimethyl-1,3,2-dioxaborole cyclohexane is as follows: aryl halide (0.67 mmol, 1.0 eq.), aryl boronate (0.81 mmol, 1.2 eq.) were added to a Schlenk tube in the following order, potassium phosphate or CsF (3.0 eq.), Pd catalyst (0.1 eq.) and 2-(dicyclohexylphosphino)biphenyl (0.2 eq.). When using Pd(OAc)2 as the catalyst, CsF is required as the base (see Table 8, entries 13-15). Subsequently, a PTFE-coated stirrer was added to the reaction system and the reaction was carried out at room temperature. The reaction mixture was degassed under high vacuum three times for 10 min each and backfilled with nitrogen. Anhydrous dioxane was added through the T-neck and the reaction mixture was heated to 110°C and kept for 18 hours. Upon completion of the reaction, the mixture was cooled to room temperature and diluted with dichloromethane (10 mL). The reaction solution was filtered and the filtrate was washed with dichloromethane (100 mL). Finally, the filtrate was concentrated and purified by silica gel column chromatography.
