反应详情

1-pyridin-3-yl-1H-pyrazol-4-ylamine (0.6 g, 3.7 mmol) was dissolved in isopropyl acetate (8.5 ml). To the mixture, acetone (0.261 g, 4.5 mmol), trifluoroacetic acid (0.855 g, 7.5 mmol) and sodium triacetoxyborohydride (0.945 g, 4.5 mmol) were added. The reaction was stirred under nitrogen at room temperature for 4.5 hours and then quenched with 10% sodium hydroxide solution until the pH reached ˜9. The layers were separated, and the aqueous phase was extracted with ethyl acetate. The organic extracts were combined, dried over sodium sulfate and concentrated to dryness. The crude material was purified by silica gel chromatography (gradient elution of 5% methanol/dichloromethane) to give the title compound as an off white solid (0.35 g, 46%): mp 105-107° C.; 1H NMR (300 MHz, CDCl3) δ 8.82 (d, J=2.2 Hz, 1H), 8.63 (dd, J=4.8, 1.5 Hz, 1H), 8.13 (d, J=1.8 Hz, 1H), 8.03 (d, J=2.7 Hz, 1H), 7.94-7.77 (m, 1H), 7.38 (dt, J=15.2, 7.6 Hz, 1H), 6.99 (t, 1H), 3.72 (m, 1H), 1.30 (t, J=10.0 Hz, 6H). ESIMS 214 m/z (M+1).

1. customquenched with 10% sodium hydroxide solution until the pH
2. customThe layers were separated
3. extractionthe aqueous phase was extracted with ethyl acetate
4. dry with materialdried over sodium sulfate
5. concentrationconcentrated to dryness
6. customThe crude material was purified by silica gel chromatography (gradient elution of 5% methanol/dichloromethane)