反应详情

A solution of 2-chloro-5-(chlorocarbonyl)benzothiazole (321 mg, 1.38 mmol, prepared according to U.S. Pat. No. 3,654,296) and ferric acetylacetonate (14.7 mg, 0.042 mmol) in anhydrous tetrahydrofuran (13.8 mL) was cooled in an ice-methanol bath (−20° C.), stirred under a nitrogen atmosphere, and treated dropwise over 5 minutes with 1M methyl magnesium chloride in tetrahydrofuran (1.38 mL). The resulting mixture was stirred at −15° C. for 15 minutes then at room temperature for 30 minutes. The mixture was treated with 2N hydrochloric acid (1.38 mL), diluted with water, and extracted with ethyl acetate. The extracts were washed with 5% aqueous sodium bicarbonate and brine, dried over magnesium sulfate, filtered, and evaporated in vacuo to white solid (299 mg). The crude product was purified by flash chromatography on silica gel (25 g, loaded as a dichloromethane solution and eluted with 2% ethyl acetate in dichlormethane) to afford 5-acetyl-2-chlorobenzothiazole (201 mg) as a white solid.

1. stirringThe resulting mixture was stirred at −15° C. for 15 minutes
2. extractionextracted with ethyl acetate
3. washThe extracts were washed with 5% aqueous sodium bicarbonate and brine
4. dry with materialdried over magnesium sulfate
5. filtrationfiltered
6. customevaporated in vacuo to white solid (299 mg)
7. customThe crude product was purified by flash chromatography on silica gel (25 g
8. washeluted with 2% ethyl acetate in dichlormethane)