Acetic Anhydride → 1-[2-(Propan-2-yl)pyrazolo[1,5-a]pyridin-3-yl]ethan-1-one

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Reaction Steps

2-Isopropyl-pyrazolo[1,5-a]pyridine (10.00 g, 66.7 mmol), acetic anhydride (100 ml), and concentrated sulfuric acid (10 drops) were combined and stirred for 3 hours at reflux. The reaction mixture was cooled to room temperature and poured into ice water (300 ml). The mixture was quenched with 2 N sodium hydroxide until the pH>10, and the quenched solution was extracted with ethyl acetate. The organic layer was dried over sodium sulfate, filtered, and concentrated in vacuo. The crude material was purified by silica gel flash chromatography (0 to 40% ethyl acetate in hexanes) to give 11.8 g (87%) of 1-(2-isopropyl-pyrazolo[1,5-a]pyridin-3-yl)-ethanone. 1H-NMR (250 MHz, DMSO-d6) δ 8.47 (d, J=6.8 Hz, 1H), 8.12 (d, J=9.0 Hz, 1H), 7.38 (t, J=7.3 Hz, 1H), 6.89 (t, J=6.0 Hz, 1H), 3.76 (sept, J=6.9 Hz, 1H), 2.60 (s, 3H), 1.39 (d, J=6.8 Hz, 6H); LC/MS 203.3 m/z (M+H+).

Provenance & Evidence