Reaktion #85376

Reaktionsgleichung

Sodium borohydride

3-chloro-1-(pyridin-3-yl)-1H-pyrazol-4-amine

3-(3-chloro-4-amino-1H-pyrazol-1-yl)pyridine

methanol

Acetaldehyde

→

solid

Ausbeute 58.0%

3-Chloro-N-ethyl-1-(pyridin-3-yl)-1H-pyrazol-4-amine

Ausbeute 58.0%

Lösungsmittel

ethyl acetate

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigeto give a clear solution
2. 2
   workup.STIRRINGthe reaction was stirred at 20° C. for 6 hours
3. 3
   Sonstigea major product formed
4. 4
   SonstigeThe reaction mixture was quenched with water (10 mL)
5. 5
   Einengenconcentrated under reduced pressure
6. 6
   Sonstigeto remove methanol
7. 7
   workup.ADDITIONEthyl acetate (10 mL) was added
8. 8
   Einengenthe organic layer was concentrated to dryness
9. 9
   SonstigeThe residue was purified by flash column chromatography
10. 10
    workup.ADDITIONThe fractions containing pure product
11. 11
    Einengenconcentrated

Vorschrift

A 3-neck, 100 mL round bottom flask was charged with 3-chloro-1-(pyridin-3-yl)-1H-pyrazol-4-amine (5d) (500 mg, 2.57 mmol) and methanol (5 mL) The mixture was stirred for 5 minutes to give a clear solution. Acetaldehyde (136 mg, 3.09 mmol) was added and the reaction was stirred at 20° C. for 6 hours. Sodium borohydride (194 mg, 5.14 mmol) was added and the reaction was stirred at 20° C. for 1 hour, at which point thin layer chromatography analysis [Eluent: ethyl acetate] indicated that some starting material remained and a major product formed. The reaction mixture was quenched with water (10 mL) and concentrated under reduced pressure to remove methanol. Ethyl acetate (10 mL) was added and the organic layer was concentrated to dryness. The residue was purified by flash column chromatography using 20-40% ethyl acetate/hexanes as eluent. The fractions containing pure product were combined and concentrated to afford a white solid (328 mg, 58%). The spectral characterization was in agreement with the product prepared previously.

Quelle