Methanesulfonic Acid → 3-Methyl-1-(2-pyridinyl)-1,9-dihydro-4H-pyrazolo[3,4-b]quinolin-4-one

Temperature

100 °C

A mixture of methanesulfonic acid (120 mL, 0.84 mol) and phosphorus pentoxide (24.0 g, 0.17 mol) was heated at 100° C. The mixture was stirred thoroughly at the same temperature, with the gradual addition of powdery 2-[[3-methyl-1-(2-pyridinyl)-1H-pyrazol-5-yl]amino]benzoic acid (24.0 g, 82 mmol). The reaction mixture was heated and stirred at the same temperature further for 15 minutes. The mixture was allowed to cool to room temperature, and water was added thereto. The solution was made basic by the addition of an aqueous sodium hydroxide solution, and organic matter was extracted with chloroform. The extract was washed with saturated brine and water, dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. The residue thus obtained was purified by basic silica gel column chromatography (chloroform). The crystals thus obtained we dissolved in a mixture of ethyl acetate (300 mL) and methanol (300 mL) under heating, and heated under reflux for 30 minutes after the addition of activated carbon (2.5 g). The hot solution was filtered, and the solvents were evaporated under reduced pressure. The residue was recrystallized from ethyl acetate to give the title compound (15.1 g, 67% yield).

1. temperatureThe reaction mixture was heated
2. temperatureto cool to room temperature
3. extractionwas extracted with chloroform
4. washThe extract was washed with saturated brine and water
5. dry with materialdried over anhydrous magnesium sulfate
6. customthe solvent was evaporated under reduced pressure
7. customThe residue thus obtained
8. customwas purified by basic silica gel column chromatography (chloroform)
9. customThe crystals thus obtained we
10. temperatureunder heating
11. temperatureheated
12. temperatureunder reflux for 30 minutes
13. additionafter the addition of activated carbon (2.5 g)
14. filtrationThe hot solution was filtered
15. customthe solvents were evaporated under reduced pressure
16. customThe residue was recrystallized from ethyl acetate

ORD record

ord-b47a64f190864c878a0747bf4d586f6f

Source dataset

uspto-grants-2005_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06949648B2