Tert-butyl(trans-3-(3-amino-1H-pyrazolo[3,4-b]pyridin-1-yl)cyclobutyl)carbamate (from example 113, step 2, 0.210 g, 0.692 mmol) was dissolved in methanol (4 mL) and acetic acid (3 drops). 1-Acetyl-4-piperidone (0.100 ml, 0.812 mmol) was added and the mixture heated at 60° C. for 1 hour. The solution was cooled and sodium cyanoborohydride (0.065 g, 1.034 mmol) was added. The reaction was stirred for 14 hours at room temperature. Saturated sodium bicarbonate (10 mL), water (50 mL) and ethyl acetate (100 mL) were added and the mixture stirred for 20 minutes. The phases were separated and the organic dried with magnesium sulfate before evaporating to dryness under reduced pressure. Purification using silica chromatography (0-10% methanol in dichloromethane gradient) gave the desired tert-butyl(trans-3-(3-((1-acetylpiperidin-4-yl)amino)-1H-pyrazolo[3,4-b]pyridin-1-yl)cyclobutyl)carbamate (0.134 g, 0.313 mmol, 45.2% yield).
