Carbon Dioxide → (E)-4-(2-Chloro-4-biphenylyl)-3-pentene-2-one

Participants

Reaction Steps

208.0 Gm (1.85 mols) of potassium tert.-butylate were added all at once to a solution of 284.0 gm (1.23 mols) of 4-acetyl-2-chloro-biphenyl and 292.0 gm (1.85 mols) of ethyl (E)-3-ethoxy-crotonate in 1.8 liters of anhydrous dimethylformamide. The temperature rose at once from +20°C to +38°C, and the mixture turned red. The mixture was stirred for 1 hour at 32° to 35°C, then 200 ml of concentrated hydrochloric acid were added dropwise to the warm batch, and the resulting mixture was heated at a temperature of 90°-100°C for 30 minutes. After the carbon dioxide evolution had ceased, the cooled mixture was poured into 2 liters of ice water and extracted exhaustively with ether. The combined ether extracts were washed with water, with a saturated aqueous sodium bicarbonate solution and again with water, dried over sodium sulfate and evaporated. The oily residue was distilled in a moderate vacuum (b.p. 170°-175° C at 0.3 mm Hg) and subsequently recrystallized from cyclohexane and petroleum ether. 273.6 Gm (82% of theory) of pale yellow crystals, m.p. 66°-67°C, were obtained.

Provenance & Evidence