反应详情

温度

190 °C

A mixture of 93.4 g of 3B, 750 ml of DMSO, 48 g of 50% aqueous sodium hydroxide and 45.9 g of 3-chloro-1-propene was stirred for 8 hours at 75°-80° C., then for 16 hours at room temperature, was mixed with 3 liters of ice water and the resulting mixture was extracted with methylene chloride. The extract was washed with water, dried (MgSO4) and evaporated to dryness. The residue was placed in a flask purged with nitrogen, in a nitrogen atmosphere was heated slowly to 190° C. (one hour) and held at 185°-195° C. for two hours, cooled to room temperature, and dissolved into 250 ml of acetic acid. To this solution 150 ml of 48% aqueous hydrogen bromide solution was added, the mixture was stirred at reflux for three hours, mixed with 2 liters of ice water and the resulting mixture was extracted with a 1:1 v:v mixture of hexane and ether. The extract was washed with water, 5% aqueous sodium bicarbonate solution, dried (MgSO4), charcoaled and concentrated to dryness. The residue was crystallized from 500 ml of 9:1 v:v hexane/ether mixture, giving 2,3-dihydro-2,5-dimethyl-4-chloro-7-nitrobenzofuran (3C), m.p.: 114°-116° C.

1. waitfor 16 hours at room temperature
2. extractionthe resulting mixture was extracted with methylene chloride
3. washThe extract was washed with water
4. dry with materialdried (MgSO4)
5. customevaporated to dryness
6. customThe residue was placed in a flask
7. custompurged with nitrogen, in a nitrogen atmosphere
8. waitheld at 185°-195° C. for two hours
9. temperaturecooled to room temperature
10. dissolutiondissolved into 250 ml of acetic acid
11. additionTo this solution 150 ml of 48% aqueous hydrogen bromide solution was added
12. stirringthe mixture was stirred
13. temperatureat reflux for three hours
14. additionmixed with 2 liters of ice water
15. extractionthe resulting mixture was extracted with a 1:1 v
16. additionv mixture of hexane and ether
17. washThe extract was washed with water, 5% aqueous sodium bicarbonate solution
18. dry with materialdried (MgSO4)
19. concentrationconcentrated to dryness
20. customThe residue was crystallized from 500 ml of 9:1 v