In a dried reaction flask, the crude 2-(3-chloro-4-cyanophenyl)-3-cyclopentyl-3,3a,4,5-tetrahydro-2H-pyrazolo[3,4-f]quinoline-7-carboxylic acid (Compound 1) (0.4 g, about 0.9 mmol), the crude 2-(methylsulfonyl)ethylamine trifluoroacetate (1.258 g, about 4.06 mmol), DIEA (0.86 mL, 4.97 mmol), HATU (1.742 g, 4.581 mmol) and triethylamine (1.08 mL, 7.743 mmol) were added a mixed solvent of DMF (4.5 mL) and dichloromethane (4.5 mL). The mixture was stirred at room temperature for 24 hr, and was concentrated at reduced pressure. Water was added to the residue and the mixture was filtered to produce a crude yellow solid, which was then washed with methanol to produce a purified product (0.378 g) in 79.8% yield.
