Dimethylformamide → 6,7-Bis-(acetyloxy)-4-oxo-4H-1-benzopyran-3-carboxaldehyde

Participants

Reaction Steps

To a solution of [4,5-bis(acetyloxy)-2-hydroxyphenyl]ethanone (2.74 g, 0.0109 mol) in dimethylformamide (10 ml) at -78° C. under nitrogen was added phosphorous oxychloride (3.85 ml, 0.0414 mol) over 15 minutes. The reaction was kept at -78° C. for 15 minutes, 0° C. for 30 minutes and 22° C. for 4 hours. The reaction was poured into ice water (120 ml). The resulting precipitate, A, was stirred for 30 minutes, filtered and washed with water (3×20 ml). The filtrate, A, was extracted with chloroform (2×150 ml) and the organic extracts were combined, washed with water (3×200 ml), dried, filtered, and concentrated in vacuo to give an oily residue, C. The precipitate, A, was dissolved in acetone (50 ml) and the organic solution was dried over sodium sulfate, filtered and concentrated to 20 ml. Crystals formed and hexane (5 ml) was added. The crystals, B, were filtered and dried to give 1.32 g of the title compound, melting point 133°-135° C. The mother liquors from B and the residue, C, were combined and concentrated to dryness. The residue was crystallized from dichloromethane:hexane to give an additional 531 mg of desired product.

Provenance & Evidence