Aluminium lithium hydride → 1-(2-methoxyphenyl)-3-methyl-1H-pyrazole-4-carbaldehyde

Participants

Reaction Steps

A solution (50 mL) of methyl 1-(2-methoxyphenyl)-3-methyl-1H-pyrazole-4-carboxylate (10.3 g) synthesized in the above-mentioned (1) in tetrahydrofuran was added to an ice-cooled solution (350 mL) of lithium aluminum hydride (1.6 g) in tetrahydrofuran. The ice bath was removed, and the reaction mixture was stirred at room temperature for 1 hr. The mixture was ice-cooled again, and water (4.2 mL), 1N aqueous sodium hydroxide solution (21.0 mL) and water (4.2 mL) were successively added dropwise to quench the reaction. The residue was filtered through celite, and the filtrate was concentrated under reduced pressure to give a crude product (2.5 g) of 1-(2-methoxyphenyl)-3-methyl-1H-pyrazole-4-methanol as a pale-yellow oil. This was dissolved in toluene (50 mL), manganese dioxide (1.0 g) was added, and the mixture was heated under reflux with a Dean-Stark trap for 1 hr. The reaction mixture was allowed to cool to room temperature, and manganese dioxide was collected by filtration. The solvent was evaporated under reduced pressure to give the title object compound (2.2 g, 87%) as a colorless solid.

Provenance & Evidence