Hydrochloric Acid → Benzyl 5-methyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazole-4-carboxylate

Participants

Reaction Conditions

Reaction Steps

A suspension of 3-methyl-1-phenyl-1H-pyrazol-5-ol (10.0 g, 57 mmol) and calcium hydroxide (8.5 g, 115 mmol) in dry 1,4-dioxane (100 mL) was heated to 50° C. for 20 min. The suspension was chilled to 10° C. and benzyl chloroformate (8.2 ml, 57 mmol) was in dioxane (10 mL) added. The resultant was heated to 90° C. for 3 h, cooled to 25° C. and then, chilled (0° C.) 1 M HCl (200 mL) was added. The mixture was stirred at 25° C. overnight. A solid collected by filtration was washed with cold EtOH (2×25 mL) and ether (50 mL), dried at 80° C. (sand bath) exposed to air for 4 h to give the title compound (14.0 g, 79% yield) as an off-white solid. MS (ESI pos. ion) m/z: 309 (MH+). Calc'd exact mass for C18H16N2O3 308.

Provenance & Evidence