3,4-dihydro-2H-pyran → 5-(Bromomethyl)-1-(2-tetrahydropyranyl)indazole

Participants

Reaction Steps

A yellow suspension of 5-(bromomethyl)-1H-indazole hydrogen bromide (compound 92, 3.0 g, 14 mmol) and 3,4-dihydro-2H-pyran (Aldrich, 2.4 g, 29 mmol) in THF (100 mL) was heated at 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 mixture was diluted with methylene chloride (250 mL), washed with saturated aqueous NaHCO3, water and brine. After drying (MgSO4), the solvent was removed under vacuum to give a yellow oil. Flash chromatography yielded the title compound (93, 3.34 g, 80%). TLC Rf 0.58 (70:30 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