反应详情

To a solution of commercially available 2,6-dichloro-5-methoxy pyrimidine (100 g, 0.55 mol) in dry tetrahydrofuran was added, dropwise, 1 M vinyl magnesium bromide in tetrahydrofuran solvent (124 g, 0.94 mol) over one hour (h) at room temperature. The mixture was then stirred for 4 h at room temperature. Excess Grignard reagent was quenched by addition of acetone (200 mL) while the temperature of the mixture was maintained at a temperature below 20° C. Thereafter, 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) (151 g, 0.67 mol) was added at once and stirred overnight. A yellow solid precipitated out. The solid was filtered and washed with ethyl acetate (500 mL). The filtrate was concentrated under reduced pressure and the resulting crude compound was diluted with ethyl acetate (2 L). The resulting undissolved, dark, semi-solid was separated by filtration using ethyl acetate. It was further concentrated under reduced pressure to provide a crude compound, which was purified by column chromatography. The compound was eluted with 5% to 10% ethyl acetate in hexanes mixture to provide the title compound (70 g, 60%): mp 60-61° C.; 1H NMR (CDCl3) δ 3.99 (s, 3H), 5.85 (d, 1H), 6.75 (d, 1H), 6.95 (dd, 1H).

1. customExcess Grignard reagent was quenched by addition of acetone (200 mL) while the temperature of the mixture
2. temperaturewas maintained at a temperature below 20° C
3. stirringstirred overnight
4. customA yellow solid precipitated out
5. filtrationThe solid was filtered
6. washwashed with ethyl acetate (500 mL)
7. concentrationThe filtrate was concentrated under reduced pressure
8. additionthe resulting crude compound was diluted with ethyl acetate (2 L)
9. customThe resulting undissolved, dark, semi-solid was separated by filtration
10. concentrationIt was further concentrated under reduced pressure
11. customto provide a crude compound, which
12. customwas purified by column chromatography
13. washThe compound was eluted with 5% to 10% ethyl acetate in hexanes mixture