Pyrrolidine → 6-bromo-2-(tetrahydro-2H-pyran-3-yl)chroman-4-one

Reaction equation

[Br:1][C:2]1[CH:3]=[CH:4][C:5]([OH:11])=[C:6]([C:8](=[O:10])[CH3:9])[CH:7]=1.[O:12]1[CH2:17][CH2:16][CH2:15][CH:14]([CH:18]=O)[CH2:13]1.N1CCCC1>CO>[Br:1][C:2]1[CH:7]=[C:6]2[C:5](=[CH:4][CH:3]=1)[O:11][CH:18]([CH:14]1[CH2:15][CH2:16][CH2:17][O:12][CH2:13]1)[CH2:9][C:8]2=[O:10]

Participants

Procedure

A solution of 1-(5-bromo-2-hydroxyphenyl)ethanone (18 g, 83.70 mmol), tetrahydro-2H-pyran-3-carbaldehyde (9.55 g, 83.70 mmol) and pyrrolidine (6.95 mL, 83.70 mmol) in MeOH (125 mL) was heated to reflux for 4.5 h. The mixture was allowed to reach r.t. and concentrated. The residue was dissolved in EtOAc (150 mL) and washed with 1M NaOH (80 mL), 1M HCl (80 mL), and brine (80 mL) successively. The organic phase was concentrated, the residue was purified by flash chromatography with a gradient of 10% EtOAc in heptane to 40% EtOAc in heptane to give the title compound (18 g, 69% yield): 1H NMR (500 MHz, DMSO-d6) δ ppm 1.50 (m, 3 H), 1.79 (m, 0.5 H), 1.94 (m, 1.5 H), 2.67 (m, 1 H), 2.86 (m, 1 H), 3.30 (m, 2 H), 3.78 (m, 1 H), 3.84 (m, 0.5 H), 4.04 (dd, 0.5 H), 4.44 (m, 1 H), 7.05 (dd, 1 H), 7.71 (m, 1 H), 7.79 (d, 1 H); MS (ES+) m/z 311 [M+H]+.