Trifluoroacetic acid → ethyl 6-cyclopropyl-1H-pyrazolo[3,4-b]pyridine-4-carboxylate

Participants

Reaction Steps

To a 20 mL microwave vial were combined ethyl 6-cyclopropyl-1-{[4-(methyloxy)phenyl]methyl}-1H-pyrazolo[3,4-b]pyridine-4-carboxylate (2.05 g, 5.83 mmol), trifluoroacetic acid (6.74 ml, 88 mmol) and anisole (1.912 ml, 17.50 mmol). The reaction vessel was sealed and irradiated (microwave) at 100° C. for 5 minutes. After cooling to room temperature, the reaction mixture was concentrated in vacuo. The residue was diluted with water (20 mL) and then saturated NaHCO3 until basic. The contents were extracted with DCM (4×20 mL). The combined organic layers were washed with water, brine, dried over MgSO4, filtered and concentrated in vacuo. The crude product was purified via silica gel chromatography (eluent: 0 to 20% EtOAc:Hex). The final product was obtained as 1.06 g (79%). LCMS E-S (M+H)=232.2. 1H NMR (400 MHz, DMSO-d6) δ ppm 0.95-1.21 (m, 4 H) 1.41 (t, J=7.07 Hz, 3 H) 2.33-2.46 (m, 1 H) 4.44 (q, J=7.07 Hz, 2 H) 7.67 (s, 1 H) 8.26 (d, J=1.26 Hz, 1 H) 13.75 (s, 1 H).

Provenance & Evidence