Pivaloyl chloride → HCID 502058, compound

Participants

Reaction Steps

To a solution of 5,7-dihydroxy-4-propylcoumarin (2) (1.10 g, 5 mmol) in pyridine (12 mL) and THF (6 mL) was added pivaloyl chloride (0.673 mL, 5.5 mmol) and the reaction mixture was allowed to stir at room temperature for 24 h. TLC revealed formation of a new less polar spot and unreacted starting material. In an effort to drive the reaction to completion, pivaloyl chloride (0.50 mL) was added and the reaction continued to stir at room temperature for another 72 h. The pyridinium hydrochloride was removed by filtration and washed a few times with ethyl acetate. The organic solutions were combined and washed, successively, with 1 M HCl (2×25 mL), water (25 mL), aqueous saturated sodium bicarbonate (25 mL). After being dried over sodium sulfate and concentrated under vacuum, the crude product was purified by silica gel chromatography (2:1 hexane/ethyl acetate) to obtain 8b as a white solid (1.90 g, 98% yield). mp 110-112° C.; Rf=0.49 (4:1 hexane/ethyl acetate); 1H-NMR (CDCl3),: 1.03 (3H, t, J=7.8 Hz), 1.36 (9H, s), 1.41 (9H, s), 1.69 (2H, sextet, J=7.4 Hz), 2.81 (2H, t, J=7.8 Hz), 6.22 (1H, s), 6.60 (1H, d, J=2.4 Hz), 7.03 (1H, d, J=2.1 Hz); 13C-NMR (CDCl3): 13.5, 20.7, 26.4, 26.8, 26.9, 36.4, 39.2, 39.4, 108.6, 111.5, 113.4, 114.2, 149.4, 152.7, 154.9, 155.4, 159.9, 177.1; IR (film): 3090, 2971, 2941, 2876, 1757, 1615, 1481, 1422, 1273 cm−1; MS m/e 389 (M+1); Anal. Calcd. for C22H28O6: C, 68.02; H, 7.26. Found: C, 67.77; H, 7.18.

Provenance & Evidence