反应详情

A stirring solution of 53.4 g (0.23 mol) of 1-tert-butoxycarbonyl-3-methylindazole, prepared as in Part B, in 1.0 L of CCl4 is heated to reflux, and then a mixture of 45.1 g (0.25 mol, 1.1 equiv) of N-bromosuccinimide and 5.7 g (23.5 mmol, 0.1 equiv) of benzoyl peroxide is added portionwise over 5 min as a solid. The resulting solution is heated at reflux for 4.5 h, then cooled to RT. The reaction mixture is filtered through a pad of Celite to remove the precipitated succinimide, and the solvent is removed in vacuo. Purification of the crude material by gradient silica gel flash column chromatography using hexane/EtOAc 15/1 to hexane/EtOAc 3/1 as eluent afforded 43.2 of the title compound as a white solid: 1H NMR (CDCl3, 300 MHz) δ8.20 (d, 1H, J=7.8), 7.88 (d, 1H, J=7.8), 7.60 (dd, 1H, J=7.3, 7.3), 7.41 (dd, 1H, J=7.3, 7.3), 4.91 (s, 2H), 1.77 (s, 9H); ;TLC Rf =0.56 (EtOAc/Hexane 1/5).

1. temperatureto reflux
2. additionis added portionwise over 5 min as a solid
3. temperatureThe resulting solution is heated
4. temperatureat reflux for 4.5 h
5. filtrationThe reaction mixture is filtered through a pad of Celite
6. customto remove the precipitated succinimide
7. customthe solvent is removed in vacuo
8. customPurification of the crude material by gradient silica gel flash column chromatography