反应详情

Iodoethane (26 ml) is added to a mixture of 2-bromo-3-pyridinol (Aldrich, 22.75 g), potassium carbonate anhydrous (32.541 g) and DMF (258 ml). The mixture is stirred at 80-85° for 3.25 hr, at which time the mixture is cooled in an ice water bath and potassium carbonate is then filtered off and washed with dichloromethane. The filtrate is concentrated under reduced pressure and the residue is dissolved in ethyl acetate (570 ml) and washed with water (300 ml). The aqueous layer is backwashed with ethyl acetate (500 ml) and each of the organic phases are washed with saline (114 ml). The organic phases are combined, dried with magnesium sulfate and concentrated under reduced pressure. The crude material is chromatographed (silica gel; eluting with ethyl acetate/hexane (20/80) to give 2-bromo-3-ethoxypyridine (XXVIIIa, Chart G), MS (m/z) 201, 203; IR (neat) 1448, 1294, 1389, 1420 and 1205 cm-1.

1. temperatureis cooled in an ice water bath
2. filtrationpotassium carbonate is then filtered off
3. washwashed with dichloromethane
4. concentrationThe filtrate is concentrated under reduced pressure
5. dissolutionthe residue is dissolved in ethyl acetate (570 ml)
6. washwashed with water (300 ml)
7. washeach of the organic phases are washed with saline (114 ml)
8. dry with materialdried with magnesium sulfate
9. concentrationconcentrated under reduced pressure
10. customThe crude material is chromatographed (silica gel
11. washeluting with ethyl acetate/hexane (20/80)