Potassium Carbonate → 6-(2'-Formyl-biphenyl-4-yl)-1-(4-methoxy-phenyl)-7-oxo-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylic acid ethyl ester

Participants

Reaction Steps

Method A. A suspension 1-(4-methoxy-phenyl)-6-(4-iodo-phenyl)-7-oxo-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylic acid ethyl ester (55, 2.0 g, 3.87 mmol), 2-formylphenylboronic acid (13, 870 mg, 5.81 mmol, 1.5 equiv), and K2CO3 (1.60 g, 11.6 mmol, 3.0 equiv) in toluene (18 mL), ethanol (6 mL) and H2O (6 mL) at room temperature was degassed three times under a steady nitrogen stream before being treated with Pd(PPh3)4 (22 mg, 0.02 mmol, 5% equiv) at room temperature under N2. The reaction mixture was subsequently degassed three times again before being warmed to reflux for 12 h. When HPLC showed the Suzuki coupling reaction was complete, the reaction mixture was cooled down to 5–10° C. before being treated with water (20 mL) at 5–10° C. with good stirring. The mixture was stirred for an additional 1 h at 5–10° C. before the solids were collected by filtration. The wet cake was then thoroughly washed with water (2×30 mL) and 30% EtOAc/hexane (2×20 mL), dried in vacuo at 40–45° C. for 12 h to afford the crude desired 6-(2′-formyl-biphenyl-4-yl)-1-(4-methoxy-phenyl)-7-oxo-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylic acid ethyl ester (56, 1.61 g, 1.915 g theoretical, 84%) as off-white solids, which was found to be pure enough to do the following reaction without further purification. For 56, CIMS m/z 496 (M++H, C29H25N3O5).

Provenance & Evidence