Sulfur → 5-(pyridin-3-yl)-1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazolo[3,4-b]pyridine

Participants

Reaction Steps

A solution of 5-(pyridin-3-yl)-1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazolo[3,4-b]pyridine-3-carbaldehyde (CXXXI) (65 mg, 0.21 mmol), 5-(3-fluorophenyl)pyridine-3,4-diamine (LXXV) (45 mg, 0.22 mmol) and sulfur (7 mg, 0.22 mmol) in n-butanol (10 mL) was heated at reflux overnight. The solution was cooled to room temperature, filtered and the solvent was evaporated under reduced pressure to give crude 3-(743-fluorophenyl)-3H-imidazo[4,5-c]pyridin-2-yl)-5-(pyridin-3-yl)-1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazolo[3,4-b]pyridine (CXXXII). CXXXII was dissolved in dry DCM (5 mL) before adding triethylsilane (84 μL, 0.52 mmol) and TFA (2.5 mL). The reaction was stirred at room temperature for 2 h under argon. The solvent was evaporated under reduced pressure; the residue was taken up water (10 mL), and basified with 5N NH4OH. The precipitates were filtered, washed by cold water and dried under vacuum at room temperature. The crude product was suspended in DCM (10 mL), sonicated briefly and then heated to boiling for 5 min. The solution was cooled to room temperature and the solids were filtered, washed with DCM and dried under vacuum at room temperature to produce 3-(7-(3-fluorophenyl)-3H-imidazo[4,5-c]pyridin-2-yl)-5-(pyridin-3-yl)-1H-pyrazolo[3,4-b]pyridine (3) as a yellow solid (53 mg, 0.13 mmol, 62% yield). 1H NMR (DMSO-d6) δ ppm 7.25-7.34 (m, 1H), 7.54-7.65 (m, 2H), 8.11-8.21 (m, 1H), 8.23-8.30 (m, 1H), 8.37-8.50 (m, 1H), 8.63-8.70 (m, 1H), 8.70-8.80 (m, 1H), 9.02-9.09 (m, 2H), 9.09-9.15 (m, 1H), 13.94 (brs, 1H), 14.59 (s, 1H); ESIMS found for C23H14FN7 m/z 408.1 (M+H).

Provenance & Evidence