The general procedure for the synthesis of methyl 3-bromo-5-fluorobenzoate from 3-bromo-5-fluorobenzoic acid and sodium bicarbonate is as follows:
1. Preparation of intermediate 25: methyl 3-bromo-5-fluorobenzoate
- A solution was prepared by dissolving 3-bromo-5-fluorobenzoic acid (3.1 g, 14 mmol) in methanol (30 ml).
- Concentrated sulfuric acid (3.0 ml) was slowly added to the above solution.
- The reaction mixture was heated to reflux and maintained for 1.5 hours.
- After completion of the reaction, the mixture was cooled to room temperature.
- The cooled reaction mixture was neutralized by slowly pouring it into 400 ml of saturated aqueous sodium bicarbonate solution.
- The aqueous phase was extracted twice with diethyl ether (250 ml) and the organic layers were combined.
- The organic layer was dried with anhydrous magnesium sulfate and subsequently concentrated under reduced pressure to afford the target product methyl 3-bromo-5-fluorobenzoate (2.6 g, 80% yield).
The physicochemical properties of the intermediate 25 need to be further determined or obtained by consulting the relevant literature.
