Methyl chloroacetate → 6-Bromo-1-benzofuran-2-carboxylic acid

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

8.0 g (39.8 mmol) of 4-bromo-2-hydroxybenzaldehyde and 1.47 g (3.98 mmol) of tetra-n-butylammonium iodide are mixed with 22 g (159.19 mmol) of anhydrous potassium carbonate. 9.07 g (83.57 mmol) of methyl chloroacetate are added. The reaction mixture is heated at 130° C. for 4 h and then cooled to 0° C. in an ice bath. 100 ml of THF and a solution of 13.4 g (238.8 mmol) of potassium hydroxide in 50 ml of water are added, and the mixture is then stirred at RT overnight. The THF is removed under reduced pressure. The remaining aqueous phase is diluted with water and acidified with conc. hydrochloric acid. The precipitated product is filtered off and dried under high vacuum. Silica gel 60 (Merck, Darmstadt; eluent: toluene, toluene/acetic acid 50:1, toluene/acetic acid/methyl acetate 35:1:5) is used for final purification. The solvent is removed under reduced pressure. Finally, the last residues of solvent are removed under high vacuum. 3.8 g (40% of theory) of the title compound are isolated.

Herkunft & Nachweise