反应详情

To a solution of 5-bromo-7-ethyl-1H-indazole (900 mg, 4.00 mmol) in ethanol (16.0 mL) flushed with nitrogen was added palladium on carbon (128 mg, 1.2 mmol) and the mixture stirred under H2 at 1 atm. After 70 h the reaction was filtered over a pad of celite. The filtrate was collected and concentrated. The residue was dissolved in ethanol and 80 mg of palladium on carbon was added and stirred under H2 at 1 atm. After 3 h another 80 mg of palladium on carbon was added and stirred under H2 at 1 atm. After 16 h the reaction was filtered through a pad of celite. The filtrate was collected and concentrated. The yellow solid obtained was triturated with ether, filtered and dried under vacuum to give 7-ethyl-1H-indazole (771 mg, 5.27 mmol, 119%) as an off white solid. This was used directly without further purification. MS (M+H)+=146.8; 1H NMR (CDCl3) δ: 8.54 (s, 1H), 7.78 (d, J=8.2 Hz, 1H), 7.59 (d, J=7.1 Hz, 1H), 7.43 (t, J=7.1 Hz, 1H), 3.25 (q, J=7.4 Hz, 2H), 1.48 (t, J=7.5 Hz, 3H).

1. filtrationAfter 70 h the reaction was filtered over a pad of celite
2. customThe filtrate was collected
3. concentrationconcentrated
4. dissolutionThe residue was dissolved in ethanol
5. addition80 mg of palladium on carbon was added
6. stirringstirred under H2 at 1 atm
7. additionAfter 3 h another 80 mg of palladium on carbon was added
8. stirringstirred under H2 at 1 atm
9. filtrationAfter 16 h the reaction was filtered through a pad of celite
10. customThe filtrate was collected
11. concentrationconcentrated
12. customThe yellow solid obtained
13. customwas triturated with ether
14. filtrationfiltered
15. customdried under vacuum