3,4-dihydro-2H-pyran → 6-(Bromomethyl)-1-(tetrahydro-2H-pyran-2-YL)-1H-indazole

Participants

Reaction Steps

A yellow suspension of 6-(bromomethyl)-1H-indazole hydrogen bromide (9.0 g, 43 mmol) (4-5) and 3,4-dihydro-2H-pyran (7.2 g, 86 mmol) in THF (200 mL) was heated at its reflux temperature for 2 hours. After cooling down to room temperature, the reaction mixture was stirred at room temperature for 12 hours under nitrogen. The reaction solution was diluted with methylene chloride (500 mL), washed with saturated NaHCO3, water and brine. After drying (MgSO4), the solvent was removed under vacuum to give a yellow oil. Flash chromatography yielded the title compound (6.6 g, 72%). TLC Rf 0.52 (80:20 of hexane-ethyl acetate); MS (electrospray) 295, 297 (M+1); 1H N MR (CDCl3) δ1.57-1.84 (m, 3H), 2.16 (m, 2H), 2.55 (m, 1H), 3.75 (m, 1H), 4.01 (m, 1H), 4.65 (s, 2H), 5.71 (d, 1H, J=9.2 Hz), 7.44 (d, 1H, J=8.8 Hz), 7.59 (d, 1H, J=8.8 Hz), 7.73 (s, 1H), 8.00 (s, 1H).

Provenance & Evidence