Ethanol → ethyl 1-tert-butyl-5-(2-chlorophenyl)-1H-pyrazole-4-carboxylate

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Reaction Steps

A mixture of 2.82 g of ethyl 2-(2-chlorobenzoyl)-3-(N,N-dimethylamino)acrylate (a compound described in JP-A 7-101940), 1.25 g of tert-butylhydrazine hydrochloride and 10 ml of ethanol was heated to reflux for 8 hours. After the reaction mixture was allowed to cool to room temperature, water was poured and the mixture was extracted with ethyl acetate. The organic layer was washed with water, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The resulting residue was subjected to silica gel column chromatography to obtain 0.48 g of ethyl 1-tert-butyl-5-(2-chlorophenyl)-1H-pyrazole-4-carboxylate of the formula:

Provenance & Evidence