Réaction #94513

Équation de réaction

8-Chloro-5,6-dihydro-4-oxo-6-phenyl-4H-pyrazolo[1,5-a][1,4]benzodiazepine-2-carboxaldehyde

end product

EtOH

hydrazine-hydrate

→

8-Chloro-2-methyl-5,6-dihydro-4-oxo-6-phenyl-4H-pyrazolo[1,5-a][1,4]benzodiazepine

Solvants

THF hexane

Conditions de réaction

Traitement

1. 1
   TempératureThe reaction was heated
2. 2
   Températureto reflux for 17 hours
3. 3
   Températurecooled
4. 4
   Concentrationconcentrated in vacuo
5. 5
   workup.ADDITIONpotassium t-butoxide added
6. 6
   Températurethe mixture heated
7. 7
   Températureto reflux for 8 hours
8. 8
   workup.ADDITIONThe reaction was poured over ice and brine and toluene
9. 9
   workup.ADDITIONadded
10. 10
    AutreThe toluene phase was separated
11. 11
    Séchagedried over Na2SO4
12. 12
    ExtractionThe aqueous phase was extracted well with CH2Cl2
13. 13
    Séchagethe combined extracts dried over Na2SO4
14. 14
    Concentrationconcentrated
15. 15
    Autrethe crude product recrystallized from THF/hexane
16. 16
    Autreto give the desired end product, mp 258°-261°
17. 17
    Autrewas obtained as colorless crystals

Mode opératoire

To a solution of 3.43 g. (10.15 mmol) of the end product of Example 15 in 60 ml. of absolute EtOH, was added 12 ml. of hydrazine-hydrate. The reaction was heated to reflux for 17 hours, then cooled and concentrated in vacuo. The residue was taken up in 60 ml. toluene; 1.0 g. potassium t-butoxide added and the mixture heated to reflux for 8 hours, then cooled to room temperature and stirred for 9 hours. The reaction was poured over ice and brine and toluene added. The toluene phase was separated and dried over Na2SO4. The aqueous phase was extracted well with CH2Cl2 and the combined extracts dried over Na2SO4. The dried solutions were combined and concentrated and the crude product recrystallized from THF/hexane to give the desired end product, mp 258°-261°. An analytical sample was prepared by an additional recrystallization from THF/hexane and was obtained as colorless crystals: mp 259°-261°.

Source