Water → 6-Bromo-2',4',5',6'-tetrahydrospiro[chroman-2,3'-pyran]-4-one

Participants

Reaction Steps

A solution of 1-(5-bromo-2-hydroxyphenyl)ethanone (8.2 g, 38.13 mmol), dihydro-pyran-3-one (4.96 g, 49.57 mmol) and pyrrolidine (4.12 mL, 49.57 mmol) in toluene (80 mL) was stirred at 50° C. for 1 h. The temperature was increased to reflux, and the reaction was refluxed for 22 h. Additional dihydro-pyran-3-one (0.5 g 5 mmol) was added and the mixture was refluxed for an additional 24 h. The mixture was allowed to reach r.t., and then water (50 mL) followed by EtOAc (100 mL) was added. The organic layer was concentrated and the residue was purified by flash chromatography using a gradient of heptane to 40% EtOAc in heptane to give the title compound (9 g, 79% yield): 1H NMR (500 MHz, CDCl3) δ ppm 1.57 (m, 1 H), 1.72 (ddd, 1 H), 1.96 (m, 1 H), 2.12 (m, 1 H), 2.71 (m, 2 H), 3.51 (d, 1 H), 3.58 (m, 1 H), 3.86 (m, 2 H), 6.96 (d, 1 H), 7.57 (dd, 5 H), 7.97 (d, 4 H); MS (ES+) m/z 297 [M+H]+.

Provenance & Evidence