Dimethylformamide → 1H-Pyrazole-4-carboxaldehyde, 3-ethyl-1-phenyl-

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Reaction Steps

To an ice cold solution of N,N-dimethylformamide (4.59 mL, 59.36 mmol) and phosphoryl chloride (5.52 mL, 59.36 mmol) add a solution of N-[1-methyl-prop-(E)-ylidene]-N′-phenyl-hydrazine (3.21 g, 19.79 mmol) in N,N-dimethylformamide (2 mL) dropwise. Warm to room temperature, then heat to 75° C. for 5 hr. Cool to room temperature and pour into an ice-cold solution of saturated potassium carbonate. Extract with DCM (3×20 mL), pass through an IST Phase Separator Frit® and concentrate. Purify (silica gel chromatography, eluting with 0:100 to 20:80 ethyl acetate:isohexane), to give 3-ethyl-1-phenyl-1H-pyrazole-4-carbaldehyde as brown solid (600 mg, 15%). MS (m/z): 201 (M+1).

Provenance & Evidence