Synthesis
To a dichloromethane (50 mL) suspension of 2-bromo-6-methylbenzoic acid (5.05 g, 23.48 mmol) was sequentially added oxalyl chloride (2.67 mg, 30.5 mmol) and N,N-dimethylformamide (DMF, 2 drops) at room temperature. The reaction mixture was stirred at room temperature for 2 hours and then concentrated under reduced pressure to remove the solvent. Methanol (10 mL) was added to the resulting residue and stirring was continued overnight. Upon completion of the reaction, the reaction mixture was concentrated under reduced pressure. To the concentrated residue was added saturated aqueous sodium bicarbonate (20 mL) and the mixture was extracted with ethyl acetate. The organic layer was dried with anhydrous magnesium sulfate and the solvent was removed under reduced pressure. The resulting methyl 2-bromo-6-methylbenzoate (5.04 g, 94% yield) was used directly in the subsequent reaction without further purification.
References
[1] Patent: EP2455370, 2012, A1. Location in patent: Page/Page column 101
[2] Patent: WO2007/47646, 2007, A2. Location in patent: Page/Page column 52
