3,4-dihydro-2H-pyran → HCID 69803802, compound

Participants

Reaction Steps

A suspension of methyl 5-bromo-1H-indazole-3-carboxylate (CXVI) (1.35 g, 5.29 mmol), pyridinium p-toluenesulfonate (0.143 g, 0.56 mmol) and 3,4 dihydro-2H-pyran (1.02 mL, 11.90 mmol) in anhydrous dichloroethane (20 mL) was refluxed 5 h under argon. The suspension was turned into the clear solution. The solution was cooled and the excess solvent was evaporated under vacuum. The residue was dissolved in EtOAc and washed with dilute NaHCO3 solution (satd. NaHCO3 soln/H2O: 1:9). The organic layer was dried over Na2SO4, filtered and concentrated. The residue was purified by column chromatography (100% hexanes→5:95 EtOAc:hexanes) to get methyl 5-bromo-1-(tetrahydro-2H-pyran-2-yl)-1H-indazole-3-carboxylate (CXVII) as a white solid (1.47 g, 4.34 mmol, 82% yield). 1H NMR (DMSO-d6) δ ppm 8.22 (d, J=1.4 Hz, 1H), 7.89 (d, J=7.2 Hz, 1H), 7.68 (dd, J=7.2, 1.6 Hz, 1H),), 6.02 (dd, J=8.0, 2.4 Hz, 1H), 3.94 (s, 3H), 3.88 (m, 1H), 3.79 (m, 1H), 2.37-2.31 (m, 1H), 2.05-1.96 (m, 2H), 1.77-1.73 (m, 1H). 1.60-1.58 (m, 2H); ESIMS found for C14H15BrN2O3 m/z 340.0 (M+H).

Provenance & Evidence