Acetone → 7-hydroxy-2,2-dimethyl-3,4-dihydro-2H-1-benzopyran-4-one

Participants

Reaction Steps

To a solution of 2,4-dihydroxy acetophenone (6.00 g, 39.4 mmol) and pyrrolidine (15.0 mL, 181 mmol) in toluene (200 mL), acetone (22.9 g, 394 mmol) was added. After heated to reflux for 16 hrs, the solvents were removed and the residue was added HCl (2.0 N, 100 mL) and brine (200 mL) then the mixture was extracted with EtOAc (150×5 mL). The combined organic layers were washed with brine, dried over Na2SO4, filtered and concentrated. The crude product was purified by SGC (eluting with petroleum ether/ethyl acetate=6/1) to give target compound (2.56 g, 33%) as a brown yellow solid. LCMS (ESI) m/z: 191.1 [M−H]+; 1H-NMR (500 MHz, CDCl3): δ 7.79 (d, J=8.0 Hz, 1H), 6.49 (dd, J=8.5, 2.0 Hz, 1H), 6.36 (d, J=2.0 Hz, 1H), 2.68 (s, 2H), 1.45 (s, 6H).

Provenance & Evidence