Sodium Hydroxide → 7-hydroxy-2,3-dihydro-4H-chromen-4-one

Participants

Reaction Steps

To a stirred 2 M solution of sodium hydroxide (500 mL, 1000 mmol) at 5° C. was added 3-chloro-1-(2,4-dihydroxyphenyl)propan-1-one (Preparation 2A, 13.6 g, 67.9 mmol) in one portion. The solution was warmed to room temperature over 2 h, re-cooled to 5° C., and the pH was adjusted to ˜2 with 6 M aqueous sulfuric acid (˜50 mL). An orange precipitant formed which was collected by vacuum filtration and dried under reduced pressure. The filtrate was extracted with ethyl acetate (3×100 mL), washed with brine, and dried over anhydrous sodium sulfate. Concentration under reduced pressure gave an orange solid. The two recovered solids were combined to give 7-hydroxychroman-4-one (9.0 g, 54.8 mmol, 81% yield). LC/MS M+1=165.0; 1H NMR (400 MHz, CDCl3) δ ppm 7.77 (1H, d, J=8.58 Hz), 6.45 (1H, dd, J=8.69, 2.31 Hz), 6.33 (1H, d, J=2.42 Hz), 5.62 (1H, br. s.), 4.33-4.66 (2H, m), and 2.58-2.90 (2H, m).

Provenance & Evidence