Trifluoroacetic acid → ethyl 5-amino-1-(2-fluorobenzyl)-1H-pyrazole-3-carboxylate

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Reaction Steps

100 g (0.613 mol) of sodium salt of ethyl cyanopyruvate (preparation analogously to Borsche and Manteuffel, Liebigs Ann. 1934, 512, 97) are treated with 111.75 g (75 ml, 0.98 mol) of trifluoroacetic acid at room temperature in 2.5 l of dioxane under argon with good stirring and the mixture is stirred for 10 min, a large part of the starting material going into solution. 85.93 g (0.613 mol) of 2-fluorobenzylhydrazine are then added and the mixture is boiled overnight. After cooling, the deposited crystals of sodium trifluoroacetate are filtered off with suction, washed with dioxane and the solution is reacted further in crude form.

Provenance & Evidence