Water → 2-Cyclohexyl-1,2-dihydro-1,5-dimethyl-3H-pyrazol-3-one

Participants

Reaction Conditions

Reaction Steps

A suspension of 2-cyclohexyl-5-methyl-1H-pyrazol-3(2H)-one (525 g, 2834 mmol) in N,N-dimethylformamide (2200 mL) was heated to 40° C. and methyl iodide (532 mL, 8502 mmol) was added. The reaction mixture was heated to 70° C. for 20 h. Further methyl iodide (177 mL, 2834 mmol) was added and the mixture was stirred at 75° C. for 3.5 hours, then 80° C. for 20 hours. The resulting mixture was concentrated under reduced pressure and the residue was triturated with TBME (2000 ml). The product was collected by filtration, washing with TBME (5×500 ml) to give a solid which was suspended in DCM (2500 ml) and water (500 ml) and neutralized with 2M potassium carbonate solution (1700 ml) to pH>9. The phases were separated and the aqueous layer was extracted with DCM (3×500 ml). The organic extracts were washed with brine (1000 ml) and concentrated under reduced pressure. The resulting residue was dissolved in ethyl acetate (2000 ml), dried over anhydrous sodium sulfate and filtered through 200 g of silica gel (40-63 μm), washing with ethyl acetate/methanol 9:1 (7×300 ml). The filtrate was concentrated under reduced pressure and to give the title compound as a brown oil.

Provenance & Evidence