Sodium Hydroxide → 6-Chloro-3-methylimidazo[1,2-b]pyridazine-2-carboxylic acid

3.9 g of ethyl 6-chloro-3-methylimidazo[1,2-b]pyridazine-2-carboxylate was suspended in 40 ml of tetrahydrofuran; 30 ml of a 1 N aqueous solution of sodium hydroxide was added, followed by stirring at room temperature for 3 hours. The mixture was concentrated under reduced pressure. The residue was adjusted to pH 4 by the addition of 50 ml of water and 1 N hydrochloric acid; the crystal precipitated was collected by filtration and dried to yield 2.55 g of 6-chloro-3-methylimidazo[1,2-b]pyridazine-2-carboxylic acid. 1.27 g of this carboxylic acid was dissolved in 20 ml of N,N-dimethylformamide; 1.07 g of N,N′-carbonyldiimidazole was added, followed by stirring at room temperature for 30 minutes. To this mixture, 0.922 g of glycine ethyl ester hydrochloride and 0.915 ml of triethylamine were added, followed by further stirring for 3 hours. 60 ml of ice water was added to the reaction mixture; the crystal precipitated was collected by filtration, washed with water and dried to yield 1.18 g of the title compound.

1. concentrationThe mixture was concentrated under reduced pressure
2. additionThe residue was adjusted to pH 4 by the addition of 50 ml of water and 1 N hydrochloric acid
3. customthe crystal precipitated
4. filtrationwas collected by filtration
5. customdried

ORD record

ord-82e8bc07553541a28cce15a1ba3296b3

Source dataset

uspto-grants-2003_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06627630B1