Isonicotinic Acid → [2-(4-Fluorophenyl)-3-(4-pyridinyl)pyrazolo[1,5-a]pyridin-5-yl]methyl Isonicotinate

Participants

Reaction Steps

2-(4-Fluorophenyl)-5-hydroxymethyl-3-(4-pyridinyl)pyrazolo[1,5-a]pyridine (Example 6. 30 mg, 0.094 mmol) and 4-pyridinecarboxylic acid (0.12 mmol) are dissolved in dimethylformamide (0.5 mL) and diethyl cyanophosphonate (35 mg, 0.2 mmol, 93% grade), followed by triethylamine (35 mg, 0.35 mmol) are added dropwise. The resulting solution is stirred at room temperature until the reaction is complete as determined by TLC and then diluted with hexane/ethyl acetate (30 mL of a 1:1 mixture) and washed with water (3×). The organic phase is then shaken with dilute hydrochloric acid. In cases were the hydrochloride salt of the product deposits at this stage it is filtered off, washed with water and then hexane and dried. If no deposit is observed, the acidic phase is separated, washed once with hexane/ethyl acetate (15 mL of a 1:1 mixture) and basified with saturated sodium bicarbonate solution. This is then extracted with dichloromethane (15 mL) five times and the dichloromethane solution dried (MgSO4), filtered and concentrated to give the title compound. 1H NMR (d6-DMSO) δ 5.43 (s, 2H), 7.15 (d, J=6.9 Hz, 1H), 7.25 (t, J=8.8 Hz, 2H), 7.30 (d, J=5.9 Hz, 2H), 7.50–7.53 (m, 2H), 7.84–7.87 (m, 3H), 8.55 (d, J=5.7 Hz, 2H), 8.79 (d, J=5.9 Hz, 2H), 8.82 (d, J=7.1 Hz, 1H); APESI-MS m/z 425 (M+1)+.

Provenance & Evidence