Imidazole → 5-[[(1,1-Dimethylethyl)dimethylsilyl]oxy]-1H-indazole

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Reaction Steps

To a stirred solution of 1H-indazol-5-ol (5.0 g, 37.3 mol) and imidazole (12.7 g, 186.5 mmol) in dichloromethane (200 mL) was added tert-butylchlorodimethylsilane (16.8 g, 112 mol) and the mixture stirred at room temperature overnight. Then the reaction mixture was washed with brine (3×50 mL) and dried over Na2SO4. The crude mixture was purified by column chromatography (silica gel, 200-300 mesh, EtOAc:petroleum ether=1:10, v/v) to give 5-(tert-Butyldimethylsilyloxy)-1H-indazole (9.5 g, yield 100%) as yellow oil. MS: (M+H)+=249.2; 1H NMR (300 MHz, CDCl3): δ 7.95 (d, 1H, J=1.2 Hz), 7.34 (dt, 1H, J=8.7, 0.75 Hz), 7.12 (s, 1H), 6.97 (dd, 1H, J=8.7, 2.1 Hz), 1.01 (s, 9H), 0.23 (s, 6H).

Provenance & Evidence