Reaction #552204

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
3. 3
   workup.STIRRINGThe cold mixture was stirred for an additional hour
4. 4
   workup.ADDITIONadded to a cold
5. 5
   workup.STIRRINGstirred
6. 6
   workup.STIRRINGThe resulting mixture was stirred at room temperature for six hours
7. 7
   workup.STIRRINGThe resulting mixture was stirred at room temperature for 18 hours
8. 8
   workup.STIRRINGThe resulting mixture was stirred at 75° C. for 30 minutes, at room temperature for two hours
9. 9
   Temperaturewas cooled to 5° C.
10. 10
    Filtrationfiltered
11. 11
    Otherdried
12. 12
    workup.ADDITIONmixed with 400 ml of methanol
13. 13
    Temperaturethe mixture was chilled to 0° C.
14. 14
    workup.ADDITIONan excess of anhydrous hydrogen chloride was added
15. 15
    OtherThe methanol was evaporated under reduced pressure
16. 16
    workup.ADDITION50% aqueous sodium hydroxide solution was added
17. 17
    Extractionthe resulting mixture was extracted with ether
18. 18
    DryingThe extract was dried (MgSO4)
19. 19
    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 then 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. The cold mixture was stirred for an additional hour and then 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, at room temperature for two hours, then was cooled to 5° C. and filtered. The filter cake was air dried, then mixed with 400 ml of methanol, the mixture was chilled to 0° C. and an excess of anhydrous hydrogen chloride was added. The methanol was evaporated under reduced pressure, the residue was taken up in water, 50% aqueous sodium hydroxide solution was added, and the resulting mixture was extracted with ether. The extract was dried (MgSO4) and the solvent was evaporated to give 2,3-dihydro-2,4-dimethyl-7-hydrazinobenzofuran (1E), as an amber syrup.

Source