1-phenyl-1H-pyrazol-3-amine → 5-Nitro-2-phenyl-2H-pyrazolo [3,4-b]pyridine

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Reaction Steps

Compound 3A (3.0 g, 18.868 mmol) and sodium nitromalonaldehyde monohydrate (2.623 g, 18.868 mmol, prepared according to the procedures reported in Org. Synth. IV. 844, (1963)) in acetic acid (100 mL) was refluxed for 24 hours. After cooling to RT, the reaction was concentrated under reduced pressure to remove most of the acetic acid. The resulting residue was dissolved in CH2Cl2 (200 mL), then washed with IN aqueous NaOH (2×200 mL), water (100 mL), saturated NaCl (100 mL). The organic layer was dried (MgSO4), and concentrated to give a dark brown residue. The residue was purified by silica gel column chromatography eluting with 2 M NH3 in MeOH/CH2Cl2 (1:99 ratio) to give the title compound, 5-nitro-2-phenyl-2H-pyrazole[3,4-b ]pyridine as a beige colored solid (300 mg). LC/MS (method A): retention time=2.62 min; (M+H)+=241.

Provenance & Evidence