Hydrazine hydrate (1:1) → 3-(n-Butyl)-5,5-dimethyl-4-phenyl-4,5-dihydropyrazole

Participants

Reaction Steps

To a magnetically stirred solution of 2-methyl-3-phenyloct-2-en-4-one (Intermediate III-1) (1.96 gram, 9.07 mmol) in absolute ethanol (15 ml) was added hydrazine.hydrate (0.88 ml, 18.14 mmol) and the resulting solution was heated at reflux temperature for 4 hours under a nitrogen atmosphere. The resulting solution was allowed to attain room temperature, concentrated and taken up in a mixture of MTBE and water. The organic layer was collected, dried over MgSO4, filtered and concentrated to give crude 3-(n-butyl)-5,5-dimethyl-4-phenyl-4,5-dihydropyrazole (Intermediate IV-1) (2.06 gram) as an oil. 1H-NMR (400 MHz, CDCl3) δ 0.80-0.89 (m, 6H), 1.23-1.37 (m, 5H), 1.42-1.54 (m, 2H), 2.06-2.35 (m, 2H), 3.52 (s, 1H), 4.90 (br s, 1H), 7.07 (br d, J˜8 Hz, 2H), 7.19-7.38 (m, 3H).

Provenance & Evidence