p-Toluenesulfonic acid → 5-bromo-1-(oxan-2-yl)-1H-indazole

Participants

Reaction Steps

To a solution of 5-bromo-1H-indazole (5 g, 25.38 mmol) in DCM (50 mL), 3,4-dihydro-2H-pyran (4.26 g, 50.76 mmol) and PTSA (2.41 g, 12.69 mmol) were added and the reaction was stirred at room temperature for 3 h. Solvent was removed under vacuum. The residue was dissolved in ethyl acetate (150 mL), washed with water (20 mL), brine (20 mL), and dried over sodium sulfate. The organic layer was concentrated under vacuum and the crude product was purified by flash chromatography using hexane/ethyl acetate to give 5-bromo-1-(tetrahydro-2H-pyran-2-yl)-1H-indazole as colorless liquid (6.95 g, 97%). 1HNMR: 400 MHz, DMSO-d6: δ 1.57-1.62 (m, 2H), 1.74-1.76 (m, 1H), 1.96-2.06 (m, 2H), 2.37-2.40 (m, 1H), 3.72-3.78 (m, 1H), 3.87-3.90 (m, 1H), 5.85-5.86 (m, 1H), 7.53-7.54 (m, 1H), 7.74 (d, J=9.20 Hz, 1H), 8.04 (d, J=1.60 Hz, 1H), 8.11 (s, 1H). LCMS: RT 2.033 min; LCMS (ES-API), m/z 283 (M+H).

Provenance & Evidence