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ChemicalBook CAS DataBase List 6-CHLORO-3-OXO-2,3-DIHYDROPYRIDAZINE-4-CARBOXYLIC ACID
50681-26-0

6-CHLORO-3-OXO-2,3-DIHYDROPYRIDAZINE-4-CARBOXYLIC ACID synthesis

3synthesis methods
Methyl 3,6-dichloropyridazine-4-carboxylate

286946-24-5

6-CHLORO-3-OXO-2,3-DIHYDROPYRIDAZINE-4-CARBOXYLIC ACID

50681-26-0

A. Methyl 3,6-dichloropyridazine-4-carboxylate (2.00 g, 10.4 mmol) was dissolved in dioxane (9.0 mL) and 1M hydrochloric acid solution (10.4 mL) was added. The reaction mixture was stirred at 90°C for 20 hours. After completion of the reaction, the mixture was cooled to 0 °C and the precipitate was collected by filtration. The precipitate was washed with cold water followed by a small amount of pyridazine acid Z.1 to afford the target product 3-oxo-6-chloro-2,3-dihydropyridazine-4-carboxylic acid (955 mg, 53% yield). The product was confirmed by HPLC-MS analysis (MS (MH)+ = 173; retention time t Ret = 0.00min; analytical method: LCMSBAS1).

-

Yield: 53%

Reaction Conditions:

with hydrogenchloride in 1,4-dioxane;water at 90; for 20 h;

Steps:

A.34
A.34 Carboxylic acid ester ED.1 (2.00 g, 10.4 mmol) is placed in dioxane (9.0 mL), combined with HCI (10.4 mL, 1 M) and stirred for 20 h at 90°C. Then the reaction mixture is cooled to 0°C, the precipitate is filtered off, washed with water and pyridazinonic acid Z.1 (955 mg, 53 %; HPLC-MS: MS(M-H)" = 173; tRet = 0.00 min; method LCMSBAS1 ) is obtained.

References:

BOEHRINGER INGELHEIM INTERNATIONAL GMBH;ENGELHARDT, Harald;KOFINK, Christiane;MCCONNELL, Darryl WO2011/131741, 2011, A1 Location in patent:Page/Page column 62-63

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