Hydrazine hydrate (1:1) → HCID 22506888, compound

Participants

Reaction Steps

3-tert-Butyl-4-hydroxy-5-methyl-5H-furan-2-one (3 g, 17.7 mmol) was dissolved in ethanol (40 ml) with hydrazine hydrate (2.73 ml, 88.5 mmol) and heated under reflux for 14 h. The volume was reduced by evaporation to ˜15 ml and heating continued for a further 48 h. The solvents were removed under high vacuum and the residue was triturated with diethyl ether to leave a white solid (crude 4-tert-butyl-5-(1-hydroxyethyl)pyrazol-3-one, 2.6 g). This white solid (2.6 g, 14 mmol) was dissolved in dichloromethane (70 ml) with tosyl chloride (3.24 g, 16.8 mmol) then cooled to 0° C. and triethylamine (2.56 ml, 18.2 mmol) was added dropwise. The reaction mixture was allowed to warm to ambient temperature then diluted with more dichloromethane (50 ml) and washed with saturated brine (1×100 ml). The organic layer was dried (Na2SO4), filtered and concentrated under vacuum to leave a residue which was purified on silica gel using 20-50% ethyl acetate in isohexane as eluent to give 4-tert-butyl-5-(1-hydroxyethyl)-3-(4-methylphenyl)sulfonyloxypyrazole (3.8 g) as a white solid. 1H NMR (360 MHz, CDCl3) δ 1.34 (9H, s), 1.50 (3H, d, J=6.7 Hz), 2.45 (3H, s), 5.26 (1H, q, J=6.7 Hz), 7.35 (2H, d, J=8.2 Hz), 7.95 (2H, d, J=8.2 Hz), 10.72 (1H, br s); MS (ES+) m/e 339 [MH]+.

Provenance & Evidence