反应详情

A mixture of 1-ethyl-5-fluoro-1,3-dihydro-4-nitro-2,1-benzisothiazole 2,2-dioxide (1.0 g, 3.8 mmol) and SnCl2.H2O (4.34 g, 19.2 mmol) in ethyl acetate (50 mL) was heated at reflux for 3 h. After completion of the reaction based on thin layer chromatography, the mixture was diluted with ethyl acetate (100 mL) and solid Na2CO3 (12.5 g) was added. The resulting mixture was vigorously stirred for 12 h and then filtered through a pad of diatomaceous earth (Celite®). The filtrate was then evaporated under reduced pressure, and the residue was subjected to flash chromatography (silica gel, chlorobutane:ether 1:10 v/v) to give 650 mg of the title compound of Step D. 1H NMR (CDCl3, 400 MHz): δ 6.94 (m,1H), 6.08 (m,1H), 4.10 (s,2H), 3.80 (br s,2H), 3.62 (q,2H), 1.36 (t,3H).

1. temperaturewas heated
2. temperatureat reflux for 3 h
3. additionwas added
4. filtrationfiltered through a pad of diatomaceous earth (Celite®)
5. customThe filtrate was then evaporated under reduced pressure