Method 1, two-step synthesis. 1) Preparation of 3-bromo-2-hydroxybenzaldehyde: 2-Bromophenol is heated under reflux with anhydrous magnesium chloride, paraformaldehyde, and triethylamine in acetonitrile. Work-up yields the product. 2) Preparation of 7-bromobenzofuran-2-carboxylic acid: The product from step 1 (crude) is heated with methyl chloroacetate, tetra-n-butylammonium iodide, and potassium carbonate. Water and THF are then added, followed by potassium hydroxide, and the mixture is stirred at room temperature overnight. Subsequent acidification and extraction/purification yield the product.
