5-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-1H-Indazole

Synthesis

1H-indazol-5-ol (1.00 g, 7.45 mmol) dissolved in 20 mL of anhydrous methylene chloride was added to a 100 mL round bottom flask. Tert-butyldimethylsilyl chloride (1.69 g, 11.18 mmol) and imidazole (0.51 g, 7.45 mmol) were added to the reaction vessel producing a cloudy white mixture. Lastly, N,Ndiisopropylethylamine (1.95 mL, 11.18 mmol) was added, giving a clear solution. The reaction was stirred overnight at room temperature. Methylene chloride was used to dilute the reaction followed by washing with NaCl (2x). The organic layer was dried over MgSO4, concentrated in vacuo, and purified using flash chromatography with a 20% EtOAc/Hexane gradient to give 5- ((tert-butyldimethylsilyl)oxy)-1H-indazole (5a) (1.72g, 93%). 1H NMR (DMSO – d6, 400 MHz) δ: 12.91 (s, 1H), 7.92 (s, 1H), 7.41 (d, J=9.0 Hz, 1H), 7.12 (d, J=1.5 Hz, 1H), 6.91 (dd, J = 8.8, 2.3 Hz, 1H), 0.96 (s, 9H), 0.18 (s, 6H).