Synthesis
The general procedure for the synthesis of 2,6-dimethoxybromobenzene from m-anisidine is as follows:
Example Preparation Example (A) Synthesis of intermediate (A)
(A-1) Synthesis of 1-bromo-2,6-dimethoxybenzene
Under argon protection, 19.3 g of 1,3-dimethoxybenzene and 500 mL of anhydrous ether were added to a flask. 105 mL (1.6 M) of hexane solution of n-butyllithium was slowly added and the reaction mixture was heated and stirred for 4 hours. Upon completion of the reaction, the mixture was cooled to room temperature, followed by further cooling to -50°C. At this temperature, 25 g of bromine was slowly added dropwise. After the dropwise addition was completed, the reaction mixture was gradually warmed to room temperature and stirring was continued for 2 hours. At the end of the reaction, 300 mL of 10% aqueous sodium thiosulfate solution was added and stirred for 1 hour to quench the reaction. The reaction mixture was extracted with ether, and the organic phase was separated and washed with saturated brine. The organic phase was dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography. The resulting crystals were washed with hexane to give 17.9 g (yield: 52%) of white crystals of 1-bromo-2,6-dimethoxybenzene.
References
[1] Journal of the Chemical Society, Chemical Communications, 1995, # 6, p. 611 - 612
[2] Journal of Organic Chemistry, 2006, vol. 71, # 2, p. 775 - 788
[3] Patent: EP2436679, 2012, A1. Location in patent: Page/Page column 46
[4] Patent: JP2015/7036, 2015, A. Location in patent: Paragraph 0234; 0236
[5] Helvetica Chimica Acta, 1990, vol. 73, # 1, p. 48 - 62
