Reaction #367074

Reaction equation

sodium nitrite

sodium dithionite

sodium sulfite

potassium chloride

hydrochloric acid

1D

7-amino-2,3-dihydro-2,4-dimethylbenzofuran

→

2,3-dihydro-2,4-dimethyl-7-hydrazinobenzofuran

Solvents

water

water

Conditions

Workup

1. 1
   Temperaturethe mixture was cooled to 0° C.
2. 2
   workup.ADDITIONwas added drop-by-drop over 15 minutes to the cold
3. 3
   workup.STIRRINGstirred mixture
4. 4
   workup.STIRRINGThe cold mixture was stirred for an additional hour
5. 5
   workup.ADDITIONwas added to a cold
6. 6
   workup.STIRRINGstirred
7. 7
   workup.STIRRINGThe resulting mixture was stirred at room temperature for six hours
8. 8
   workup.STIRRINGThe resulting mixture was stirred at room temperature for 18 hours
9. 9
   workup.STIRRINGThe resulting mixture was stirred at 75° C. for 30 minutes
10. 10
    workup.WAITat room temperature for two hours
11. 11
    Temperaturewas cooled to 5° C.
12. 12
    Filtrationfiltered
13. 13
    Otherdried
14. 14
    workup.ADDITIONmixed with 400 ml of methanol
15. 15
    Otherwas chiled to 0° C.
16. 16
    workup.ADDITIONan excess of anhydrous hydrogen chloride was added
17. 17
    OtherThe methanol was evaporated under reduced pressure
18. 18
    workup.ADDITION50% aqueous sodium hydroxide solution was added
19. 19
    Extractionthe resulting mixture was extracted with ether
20. 20
    DryingThe extract was dried (MgSO4)
21. 21
    Filtrationfiltered
22. 22
    Otherthe solvent was evaporated

Procedure

A mixture of 50 ml of concentrated hydrochloric acid and 19.8 g of 1D was stirred, warmed to 80° C. and allowed to stand at room temperature for 18 hours. Then 50 ml of ice water was added, the mixture was cooled to 0° C. and stirred while a solution of 9.6 g of sodium nitrite in 20 ml of water was added drop-by-drop over 15 minutes to the cold stirred mixture. The cold mixture was stirred for an additional hour and then was added to a cold stirred mixture of 100 g of sodium sulfite in 180 ml of water. The resulting mixture was stirred at room temperature for six hours, then 21.9 g of sodium dithionite was added, in portions. The resulting mixture was stirred at room temperature for 18 hours, then at 75° C. while 150 g of potassium chloride was added. The resulting mixture was stirred at 75° C. for 30 minutes, then at room temperature for two hours, then was cooled to 5° C. and filtered. The filter cake was air dried, mixed with 400 ml of methanol, the mixture was chiled to 0° C. and an excess of anhydrous hydrogen chloride was added. The methanol was evaporated under reduced pressure, the residue taken up in water, 50% aqueous sodium hydroxide solution was added, and the resulting mixture was extracted with ether. The extract was dried (MgSO4), filtered and the solvent was evaporated to give 2,3-dihydro-2,4-dimethyl-7-hydrazinobenzofuran (1E), as an amber syrup.

Source