反应详情

温度

-78 °C

5-[2-(3,4-Dimethoxy-phenyl)-vinyl]-3-ethyl-[1,2,4]oxadiazole (compound of Example 2, Method A, Step 2; 0.3 g, 1.15 mmol) was dissolved in dichloromethane (6 mL) and cooled to −78° C. A solution of boron tribromide (0.41 mL, 4.40 mmol) in dichloromethane (4 mL), which was cooled to −50° C., was added slowly over a period of 30 min. After 3 h, the reaction mixture was allowed to warm to room temperature and stirred for 12 h. After the completion of the reaction, the mixture was quenched by dropwise addition of methanol (5 mL) at 0° C. and stirred for 30 min at room temperature. The solvent was evaporated and the residue obtained was redissolved in 10% methanol in chloroform at 0° C., and stirred with solid sodium carbonate to obtain pH ˜9. The solvent was evaporated and the crude product obtained was purified by column chromatography (silica gel, 0.5% methanol in chloroform) to afford the title compound.

1. additionwas added slowly over a period of 30 min
2. temperatureto warm to room temperature
3. customAfter the completion of the reaction
4. customthe mixture was quenched by dropwise addition of methanol (5 mL) at 0° C.
5. stirringstirred for 30 min at room temperature
6. customThe solvent was evaporated
7. customthe residue obtained
8. customto obtain pH ˜9
9. customThe solvent was evaporated
10. customthe crude product obtained
11. customwas purified by column chromatography (silica gel, 0.5% methanol in chloroform)