HCID 22388428, compound → 2-Methylpyrazolo[1,5-a]pyridine-5-carboxylic acid
Reaction equation
[CH3:1][C:2]1[C:13](C(O)=O)=[C:5]2[CH:6]=[C:7]([C:10]([OH:12])=[O:11])[CH:8]=[CH:9][N:4]2[N:3]=1>ClCCl.CO.O>[CH3:1][C:2]1[CH:13]=[C:5]2[CH:6]=[C:7]([C:10]([OH:12])=[O:11])[CH:8]=[CH:9][N:4]2[N:3]=1Participants
4
Reactant 1
Product 1
Reagents, catalysts & solvents 2
Conditions
- Temperature
- 150 °C
Procedure
A mixture of 2-methylpyrazolo[1,5-a]pyridine-3,5-dicarboxylic acid (1.39 g) and polyphosphoric acid (13.9 g) was stirred at 150° C. with heating for 2 hr, and ice (14 g) was added under ice-cooling, which was followed by shaking to give a homogeneous solution. The reaction mixture was adjusted to pH 4 at the same temperature and diluted with dichloromethane/methanol (4:1) and water. The precipitate was collected by filtration to give the objective compound (610 mg) as a pale-brown powder. The organic layer of the mother liquor was taken, and the aqueous layer was extracted with dichloromethane/methanol (4:1). Both organic layers were combined, dried over magnesium sulfate and concentrated to dryness under reduced pressure. The residue was washed with ether to give second crystals (200 mg) as a pale-brown powder.