Dichloromethane → 6-Fluoro-3-methyl-5-nitro-1,2-benzisothiazole

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Reaction Steps

A mixture of 6-chloro-3-methyl-5-nitro-1,2-benzisothiazole (2.25 g, 9.80 mmol), potassium fluoride (2.85 g, 49.0 mmol), and 18-crown-6 (1.50 g, 5.70 mmol) in acetonitrile is heated in a sealed tube for 29 days, filtered to remove solids, and partially concentrated in vacuo to obtain a liquid. The liquid is diluted with ethyl acetate, washed sequentially with water and brine, dried over anhydrous magnesium sulfate, and concentrated in vacuo to obtain a dark, brown solid. Flash column chromatography of the solid using silica gel and a 10% to 50% ethyl acetate in hexanes gradient gives a yellow solid containing two components. Flash column chromatography of the yellow solid using silica gel and a 50% to 70% methylene chloride in hexanes gradient gives the title product as a pale, yellow solid (0.870 g, mp 118-119° C.) which is identified by NMR spectral analyses.

Provenance & Evidence