3,5-Dimethylpyrazole → HCID 66615637, compound

Participants

Reaction Conditions

Reaction Steps

At −30° C., a solution of 3,5-dimethyl-1H-pyrazole (7.2 g, 74.9 mmol) in dichloromethane (40 ml) was treated with CrO3 (7.5 g, 74.9 mmol, added in two portions) while the reaction temperature rose to −20° C. The resulting mixture was stirred at −20° C. for 0.5 h and treated within 20 min. with a solution of α-bulnesene (3.0 g, 14.7 mmol) in dichloromethane (20 ml) while the reaction temperature rose to −10° C. The resulting mixture was stirred between −20° C. and −10° C. for 4 h before allowing the reaction temperature to slowly reach 20° C. (overnight), treated with 8M aqueous NaOH (70 ml), stirred at 20° C. for 20 h, and extracted with MTBE (400 ml). The aqueous phase was extracted with MTBE (150 ml) and the joined organic phases were washed twice with 2 M aq. HCl (100 ml), once with H2O (100 ml), once with aqueous saturated NaCl solution (100 ml), dried with MgSO4, filtered, and the solvent evaporated. FC (200 g 0.015-0.040 mm-SiO2, flow: 60 ml/min., hexane/methyl t-butyl ether 100:0 to 85:15 in 30 min.) of the crude product (2.4 g) gave (3S,3aS,5R)-3,8-dimethyl-5-(prop-1-en-2-yl)-3,3a,4,5,6,7-hexahydroazulen-1(2H)-one (130 mg, 4%).

Provenance & Evidence