Potassium Hydroxide → 5,6,8,9-Tetrahydro-7H-benzo[7]annulen-7-one

Participants

Reaction Conditions

Reaction Steps

The crude dimethyl 7-oxo-6,7,8,9-tetrahydro-5H-benzo[7]annulene-6,8-dicarboxylate was dissolved in 200 mL of ethanol (EtOH) and then 100 mL of 2 N KOH. The resulting mixture was refluxed at 85° C. for 17 h. After cooling to ambient temperature, the volatiles were evaporated. To the residue was added 120 mL of 2N HCl at 0° C., the crude product was extracted by EtOAc (200 mL×2). The combined extracts were washed with brine. After being dried (MgSO4), filtered, and concentrated, the residue was purified by flash column chromatography on silica gel (hexanes/EtOAc 8:1) to afford 6.6 g (57%) of 7-oxo-6,7,8,9-tetrahydro-5H-benzo[7]annulene as a white solid: mp 40-41° C.; 1H NMR (300 MHz, CDCl3) δ: 7.21 (m, 4H), 2.94-2.90 (m, 4H), 2.63-2.60 (m, 4H); LC-MS: 161 (M+H)+.

Provenance & Evidence