Dimethyl Sulfate → 3-Methoxy-4,4,4-trifluoro-2-butenoic acid ethyl ester

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Reaction Steps

An alternative method of forming the 5-trifluoromethyl-3-hydroxy-1-methylpyrazole involves reacting ethyl 4,4,4-trifluoroacetoacetate in acetone with dimethyl sulfate in the presence of anhydrous potassium carbonate and preferably triethylmethylammonium methylsulfate to form 3-methoxy-4,4,4-trifluoro-2-butenoic acid ethyl ester. This ester is then reacted directly with methylhydrazine to form the 3- and 5-hydroxy isomer mixture of the pyrazole. The desired isomer can be separated as described above.

Provenance & Evidence