Diisopropylethylamine → ethyl 5-tert-butyl-1-(4-chloro-2-methylphenyl)-1H-pyrazole-4-carboxylate

Participants

Reaction Conditions

Reaction Steps

N-Ethyldiisopropylamine (1.553 mL, 8.97 mmol) was added to (4-chloro-2-methylphenyl)hydrazine hydrochloride (1.733 g, 8.97 mmol) and (Z)-ethyl 2-((dimethylamino)methylene)-4,4-dimethyl-3-oxopentanoate (Intermediate #83) (2.04 g, 8.97 mmol) in ethanol (30 mL). The resulting solution was stirred at 90° C. for 2 hours. The reaction mixture was evaporated to dryness and redissolved in DCM (50 mL), and washed sequentially with water (2×10 mL). The organic layer was dried over MgSO4, filtered and evaporated to afford crude product. The crude product was purified by flash silica chromatography, elution gradient 0 to 10% EtOAc in isohexane. Pure fractions were evaporated to dryness to afford ethyl 5-tert-butyl-1-(4-chloro-2-methylphenyl)-1H-pyrazole-4-carboxylate (0.891 g, 30.9%) as a orange oil.

Provenance & Evidence