Réaction #8666

Équation de réaction

2-fluorobenzyl-hydrazine

trifluoroacetic acid

sodium

ethyl cyanopyruvate

→

Ethyl 5-amino-1-(2-fluorobenzyl)pyrazole-3-carboxylate

Solvants

dioxane

Conditions de réaction

Traitement

1. 1
   workup.DISSOLUTIONdissolves
2. 2
   workup.WAITthe mixture is boiled overnight
3. 3
   TempératureAfter cooling
4. 4
   Autrethe sodium trifluoroacetate crystals which have separated out
5. 5
   Filtrationare filtered off with suction
6. 6
   Lavagewashed with dioxane
7. 7
   Autrethe remaining crude solution is reacted further

Mode opératoire

111.75 g (75 ml, 0.98 mol) of trifluoroacetic acid are added to 100.00 g (0.613 mol) of the sodium salt of ethyl cyanopyruvate (prepared in analogy to Borsche and Manteuffel, Liebigs Ann. 1934, 512, 97) while stirring efficiently in 2.5 l of dioxane at room temperature under argon, and the mixture is stirred for 10 min, during which most of the precursor dissolves. Then 85.93 g (0.613 mol) of 2-fluorobenzyl-hydrazine are added, and the mixture is boiled overnight. After cooling, the sodium trifluoroacetate crystals which have separated out are filtered off with suction and washed with dioxane, and the remaining crude solution is reacted further.

Source