2-Hydroxymethyl-1,3,4-trimethoxyanthraquinone Page 457

KMnO₄

Tetrabutylammonium chloride

KOH

2-hydroxymethyl-1,3,4-trimethoxyanthraquinone (1.39 g, 4.22 mmol) was dissolved in benzene (100 cm³) and water (50 cm³) added, tetrabutylammonium chloride (360 mg) was added, followed by powdered KMnO₄ (1 g, 6.3 mmol) and finally KOH (2.8 g).   The mixture was stirred for 3 d then the phases were separated and the organic phase extracted with water (25 cm³). The combined aqueous phases were stirred and cooled, adding Na₂SO₃ (3 g) and H₂SO₄ to acidify. The bright lemon yellow precipitate of 1,3,4-trimethoxy-9,10-dioxo-9,10-dihydro-anthracene-2-carboxylic acid was filtered and dried to give 1.20 g (83% yield).

The hydroxymethyl starting material was obtained Page 457 as a minor product from the nitrite reaction of the bromomethyl compound which gave the carboxylic acid as the major product.

δ_H (CDCl₃) 8.21m (2H), 7.78m (2H), 4.13s (3H), 4.06s (3H), 4.03s (3H)

EI-MS m/z (%), 342 (97), 312 (41), 310 (11), 309 (50), 298 (17), 297 (98)

Rosenau T, Habicher WD, Synlett, 1997(2), 208-210

DOI: 10.1055/s-1997-730