Synthesis of Coumestrol, 3,9-Dihydroxy-6H-benzofuro [3,2-c] [1] benzopyran-6-one¹

One‐pot Synthesis of Benzamidonaphtho[2,1‐b]furans and Benzamidobenzo[b]furans as Novel Polycyclic Heteroaromatic Compounds

“…Some hydroxylated benzofurans also play an important role in the natural defense mechanisms of their plants. For example, euparin 25 coumestrol, 26 dehydrotremetone, 27 and cicerfuran. 28 Due to this effect, a synthetic route leading to hydroxylated benzofurans would be of general interest.…”

The determination of isoflavones and coumestrol by capillary electrophoresis

“…For the final purification, coumestrol was acetylated with acetanhydride in pyridine and the corresponding di-O-acetylcoumestrol 2 was obtained after decomposition of the reaction mixture with water followed by extraction with chloroform. The organic solvent was then evaporated and di-O-acetylcoumestrol was crystallized, m. p. 232°C (EMERSON & BICKOFF [1958] obtained 235236°C). Convenient Zemplens deacetylation of 2 with sodium methoxide in methanol gave pure coumestrol, m. p. 368°C (LASCHOBER & KAPPE [1990] found 360°C).…”

Thianaphthen-2-one chemistry. I. Synthesis of 6H-benzothieno[3,2-c][1]benzopyran-6-ones (11-thiacoumestans)

“…This mixture was then dissolved in water, solid NaHCOs was added until slight alkalinity was achieved, and the precipitate was filtered, washed with petroleum ether (bp 30-60°), and air dried to give 1.46 g of crude light yellow solid (presumably the lactone 9: mp 98-106°(unclear melt); NMR (Me2SO-d6) 2.47 (s, 3 H, pyr-CH3), 4.67 (s, 2 H, pyr-CH2OH), 4.80 (d, 1 H, J = 7 Hz, -CHCO), 5.18-5.80 (broad, 1 H, CH2OH), 5.68 (d, 1 H, J = 7 Hz, CHS), 7.00-7.70 (m, 4 H, ArH), 8.20 (s, 1 H, pyr-H). Recrystallization from 20 ml of 50:50 benzene-MeOH yielded 1.43 g (66%) of the methyl ester as an off-white powder: mp 182.0-185.0°dec; NMR (Me2SO-de) 2.43 (s, 3 H, pyr-CHs), 3.75 (s, 3 H, OCH3), 4.58 (s 2 H, pyr-CH2OH), 4.83-5.83 (broad, 1 H, CH2OH, D20 exchangeable), 5.12 (d, 1 H, J = 8 Hz, CHS), 7.00-7.50 (m, 4 H, ArH), 7.98 (s, 1 H, pyr-H), D20 showed two exchangeable protons; ir (Nujol) 3150 (OH) and 1730 cm-1 (C=0). An analytical sample of 10a was prepared by recrystallization from alcohol, mp 191.…”