Heptane → HCID 22282663, compound

Participants

Reaction Steps

A stirred solution of 7,8-dihydrofuro[2,3-g]indole-2-carboxylic acid and 5,6-dihydrofuro[3,2-f]indole-2-carboxylic acid (1:1) (5.46 g, 26.9 mmol) in phenyl ether (250 mL) was heated at reflux for 45 min, then allowed to cool to ambient temperature. Heptane (500 mL) was added and the mixture was passed through a heptane-packed SiO2 column under pressure. The column was eluted with heptane (1.5 L), then heptane-dichloromethane (1:1, 1L) and finally dichloromethane to afford 7,8-dihydrofuro[2,3-g]indole (230 mg, 5.4%) as a white solid. IR νmax (Nujol)/cm−1 3382, 2925, 2854, 1644, 1618, 1497, 1463, 1441, 1435, 1368, 1326, 1234, 1140, 1021, 970, 793, 719, 622, 533 and 475; NMR (400 MHz, CDCl3) δH 3.31 (2H, t, J 8.5 Hz), 4.66 (2H, t, J 8.5 Hz), 6.51 (1H, dd, J 2, 3.5 Hz), 6.73 (1H, d, J 8 Hz), 7.06 (1H, dd, J 2, 3.5 Hz), 7.39 (1H, d, J 8.5 Hz) and 7.83 (1H, brs). Also collected were 5,6-dihydrofuro[3,2-f]indole (667 mg, 15.6%) and mixed fractions (2.94 g, 68.7%). The mixed isomers were further separated by flash column chromatography [SiO2; ethyl acetate-heptane (1:3)] to afford afford 7,8-dihydrofuro[2,3-g]indole (408 mg, 9.5%) as a white solid and 5,6-dihydrofuro[3,2-f]indole (690 mg, 16%).

Provenance & Evidence