5-Hydroxy-2-methyl-1,4,4a,9a-tetrahydroanthracene-9,10-dione (see ChemSpider Synthetic Page 800)

Triethylamine

Dichloromethane

5-Hydroxy-2-methyl-1,4,4a,9a-tetrahydroanthracene-9,10-dione (0.12 g, 0.5 mmol) and Triethylamine (0.05 mL, 0.4 mmol) were dissolved in DCM (10 mL) at room temperature for one hour. The solvent was evaporated under reduced pressure to give aromatized product  (0.14 g, 87.0%) as a dark brown residue.

¹H NMR (400 MHz, CDCl₃): 2.55 (3H, s), 7.30 (1H, d), 7.62 (1H, d), 7.68 (1H, t), 7.83 (1H, d), 8.10 (1H, s), 8.2 (1H, d), 12.70 (1H, s).

13C NMR (100 MHz, CDCl₃): 183.5, 182.8, 162.5, 146.1, 136.5, 135.8, 133.5 (2), 130.9, 127.8, 127.1, 124.4, 119.5, 116.5, 22.0.

M.p. 127 ^oC

R_f = 0.44 (1:9 EtOAc/Hex)

Krohn, K., Tolkiehn, K., Lehne, V.; Schmalle, H. W.; Grutzmacher, H. Liebigs Ann. Chem. 1985, 7 ,1311–1328.