Sulfuric Acid → ethyl 2,2-bisfluoromethyl-6-iodo-2H-1-benzopyran-4-carboxylate

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Reaction Steps

To a mixture of 4.0 g of 6-amino-2,2-bisfluoromethyl-2H-1-benzopyran-4-carboxylic acid ethyl ester, 1.66 g of sulfuric acid and 40 ml of water was added a mixture of 1.09 g of sodium nitrite, 10 ml of methylene chloride and 10 ml of water with ice-cooling, and the reaction mixture was stirred with ice-cooling for 10 minutes. The reaction mixture was further combined with a mixture of 2.85 g of potassium iodide and 5 ml of water and stirred at room temperature for 1.5 hours. The reaction mixture was combined with water and extracted with methylene chloride. The organic layer was washed with an aqueous 20% sodium sulfite solution and saturated saline, then dried over sodium sulfate and concentrated under reduced pressure, and the resulting residue was subjected to silica gel column chromatography (eluent; ethyl acetate:hexane=1:1) to give 3.67 g of 2,2-bisfluoromethyl-6-iodo-2H-1-benzopyran-4-carboxylic acid ethyl ester; m.p. 89-90° C.;

Provenance & Evidence