p-Toluenesulfonic acid → 5-Bromo-3-fluoro-1-(tetrahydro-2H-pyran-2-yl)-1H-indazole

Participants

Reaction Steps

A mixture of 5-bromo-3-fluoro-1H-indazole (6.0 g, 27.9 mmol), PTSA (530.7 mg, 2.79 mmol) and DHP (3.05 g, 36.3 mmol) in dichloromethane (80 mL) was stirred at room temperature for 18 h. The reaction mixture was diluted with dichloromethane (370 mL) and washed with water (230 mL). The organic layer was dried over Na2SO4 and concentrated in vacuo. The residue was purified on a silica gel column using EtOAc in petroleum ether (1:100 to 1:15) to afford the title compound as a yellow solid (6.2 g, yield 74.3%). 1H NMR (DMSO-d6, 400 MHz): δ 7.96 (s, 1H), 7.70 (d, 1H), 7.60 (d, 1H), 5.76 (dd, 1H), 3.84-3.80 (m, 1H), 3.71-3.64 (m, 1H), 2.20-2.15 (m, 1H), 1.97-1.87 (m, 2H), 1.69-1.64 (m, 1H), 1.53-1.47 (m, 2H).

Provenance & Evidence