反应详情

A mixture of 1-(5-bromo-2-fluoropyridin-3-yl)ethanone (11 g, 51 mmol), (R)-2-methylpropane-2-sulfinamide (12.2 g, 101 mmol) and titanium (IV) ethoxide (26.1 mL, 126 mmol) in THF (100 mL) was heated to reflux for 2 h. The mixture was cooled to room temperature, brine was added and the mixture was stirred for 10 min. The suspension was filtered through silica gel. The organic phase was separated and the aqueous phase was extracted with EtOAc. The combined organic extracts were washed with brine, dried over Na2SO4, filtered, and concentrated. Purification by flash column chromatography on silica gel (eluted with 0-20% EtOAc/hexanes) gave (R,Z)—N-(1-(5-bromo-2-fluoropyridin-3-yl)ethylidene)-2-methylpropane-2-sulfinamide (16 g, 50 mmol, 99% yield) as a bright yellow oil. LC/MS (ESI) m/z=321 (M+H).

1. temperaturewas heated
2. temperatureto reflux for 2 h
3. filtrationThe suspension was filtered through silica gel
4. customThe organic phase was separated
5. extractionthe aqueous phase was extracted with EtOAc
6. washThe combined organic extracts were washed with brine
7. dry with materialdried over Na2SO4
8. filtrationfiltered
9. concentrationconcentrated
10. customPurification by flash column chromatography on silica gel (eluted with 0-20% EtOAc/hexanes)