Reaktion #48603

Reaktionsgleichung

165B

4-amino-1H-pyrazole-3-carboxylic acid ethyl ester

triethylamine

2,6-dichlorobenzoyl chloride

4-amino-1H-pyrazole-3-carboxylic acid methyl ester

→

4-(2,6-dichloro-benzoylamino)-1H-pyrazole-3-carboxylic acid

Lösungsmittel

dioxan

Reaktionsbedingungen

Aufarbeitung

1. 1
   FiltrationThe reaction mixture was filtered
2. 2
   workup.ADDITIONthe filtrate treated with methanol (50 ml) and 2M sodium hydroxide solution (100 ml)
3. 3
   Temperaturheated at 50° C. for 4 hours
4. 4
   Sonstigeevaporated
5. 5
   workup.ADDITION100 ml of water was added to the residue
6. 6
   FiltrationThe solid was collected by filtration
7. 7
   Waschenwashed with water (100 ml)
8. 8
   Sonstigesucked dry

Vorschrift

2,6-dichlorobenzoyl chloride (8.2 g; 39.05 mmol) was added cautiously to a solution of 4-amino-1H-pyrazole-3-carboxylic acid methyl ester (prepared in a manner analogous to 165B) (5 g; 35.5 mmol) and triethylamine (5.95 ml; 42.6 mmol) in dioxan (50 ml) then stirred at room temperature for 5 hours. The reaction mixture was filtered and the filtrate treated with methanol (50 ml) and 2M sodium hydroxide solution (100 ml), heated at 50° C. for 4 hours, and then evaporated. 100 ml of water was added to the residue then acidified with concentrated hydrochloric acid. The solid was collected by filtration, washed with water (100 ml) and sucked dry to give 10.05 g of 4-(2,6-dichloro-benzoylamino)-1H-pyrazole-3-carboxylic acid as a pale violet solid.

Quelle