Lithium Hydroxide → (1-Methyl-3-phenyl-1H-pyrazol-5-yl)methanol

Participants

Reaction Steps

A solution of 4-oxo-4-phenylbut-2-yn-1-yl benzoate (1a) (750 mg, 2.84 mmol) and methylhydrazine (0.30 mL, 5.68 mmol) in ethanol (25 mL) was stirred overnight at room temperature. The reaction mixture was concentrated in vacuo and the residue was taken in a mixture of ethanol (3 mL) and tetrahydrofuran (9 mL). Lithium hydroxide (204 mg, 8.51 mmol), previously dissolved in water (3 mL) was added and the mixture was stirred at room temperature for 2 hours. Ethanol and tetrahydrofuran were removed under reduced pressure and the resulting aqueous layer was extracted with ethyl acetate (2×5 mL). The organic layer was successively washed with a saturated solution of sodium hydrogenocarbonate (5 mL) and brine (5 mL) before being dried over sodium sulfate and concentrated in vacuo. The residue was purified by flash chromatography on silica gel (cyclohexane/ethyl acetate 100/0 to 50/50) to provide (1-methyl-3-phenyl-1H-pyrazol-5-yl)methanol (1b) (341 mg, 1.81 mmol, 64%).

Provenance & Evidence