反应详情

温度

110 °C

To 40 g of 2,5-dibromopyridine in 200 mL of 2-methoxyethanol is added 53 mL of anhydrous hydrazine and the mixture is heated at 110° C. for 3 hours to generate the 5-bromo-2-hydrazinopyridine. A mixture of 10 g of this hydrazinopyridine is heated at reflux overnight with 11 mL of 3-methyl-2-butanone in 40 mL of benzene equipped, using a condenser equipped with a Dean-Stark trap. All of the volatile components are removed under reduced pressure and the resulting residue is heated in 62 g of polyphosphoric acid at 140° C. for 45 minutes. The reaction mixture is poured into water, neutralized with sodium hydroxide and extracted with ethyl acetate. The resulting crude residue is purified by chromatography on silica gel, eluting with 1:1 ethyl acetate/hexanes, to yield 1.44 g of the product.

1. temperatureis heated
2. customequipped
3. customequipped with a Dean-Stark trap
4. customAll of the volatile components are removed under reduced pressure
5. temperaturethe resulting residue is heated in 62 g of polyphosphoric acid at 140° C. for 45 minutes
6. additionThe reaction mixture is poured into water
7. extractionextracted with ethyl acetate
8. customThe resulting crude residue is purified by chromatography on silica gel
9. washeluting with 1:1 ethyl acetate/hexanes