Dimethylformamide dimethyl acetal → 2-(4-Fluorophenyl)-3-(3-(dimethylamino)-2-propenoyl)-6-trifluoromethylpyrazolo[1,5-a]pyridine

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A mixture of 2-(4-fluorophenyl)-3-acetyl-6-trifluoromethylpyrazolo[1,5-a]pyridine (11.85 g, 36.77 mmol) and N,N-dimethylformamide dimethyl acetal (100 mL) was stirred at reflux for 17 h. The mixture was cooled to room temperature and then to 0° C. The resulting orange precipitate was collected by filtration, washed with cold hexanes, and dried under vacuum to afford the title compound as an orange solid, 10.17 g (73%). 1H NMR (d6-DMSO) δ 9.44 (s, 1H), 8.22 (d, 1H, J=9.4 Hz), 7.75 (m, 2H), 7.65 (d, 1H, J=9.5 Hz), 7.56 (d, 1H, J=12.4 Hz), 7.35 (m, 2H), 5.05 (d, 1H, J=12.3 Hz), 3.04 (s, 3H), 2.56 (s, 3H). MS (+ve ion electrospray) 377 (80), (M+).

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