Pyridine → 7-Bromo-5-fluoro-3-(3-fluoro-benzyl)-benzofuran-2-sulfonyl chloride

Participants

Reaction Conditions

Reaction Steps

7-Bromo-5-fluoro-3-(3-fluoro-benzyl)-benzofuran (0.97 gm, 3.0 mmol, prepared from 2-bromo-4-fluoro-phenol and 3-fluoro-cinnamaldehyde following the procedure of steps 1 and 2 of Example 8) was dissolved in dichloromethane (30 ml) and chilled to −15° C. Chlorosulfonic acid (0.26 ml, 3.9 mmol) in dichloromethane (2 ml) was added in portions, and the reaction mixture was stirred for 10 minutes then warmed to room temperature and stirred for 16 hours. To the resulting slurry was added pyridine (0.33 ml, 4.08 mmol) and phosphorus pentachloride (0.812 gm, 3.9 mmol) and the reaction mixture was stirred for 24 hours. Water was added and the reaction mixture was stirred for 30 minutes. The organic layer was separated, dried over magnesium sulfate, dried onto silica gel, and layered over a pad of silica gel in a fritted funnel. The silica gel was eluted with ethyl acetate/hexanes (1/9) to give 7-bromo-5-fluoro-3-(3-fluoro-benzyl)-benzofuran-2-sulfonyl chloride.

Provenance & Evidence