Hydrochloric Acid → 7-Phenyl-2,4,6-heptatrienoic acid

Participants

Reaction Conditions

Reaction Steps

Butyllithium (12.8 mL of 2.5 N solution) was added to 65 mL of anhydrous tetrahydrofuran (THF) at −65° C. A solution of diethylphosphonoacetic acid (2.92 g) in 25 mL of anhydrous THF was added dropwise to the stirred solution at −65° C. The resulting solution was stirred at −65° C. for an additional 30 minutes and then a solution of 5-phenyl-2,4-pentadienal (2.4 g) in 15 mL of anhydrous THF was added to the reaction at −65° C. The reaction was stirred for one hour, allowed to warm to room temperature and then stirred overnight. To the reaction was added 30 mL of water, acidified with 5% hydrochloric acid (14 mL) to a pH of 4.7 and then added an additional 20 mL of water. The aqueous layer was extracted with 10 mL of ether twice and with 10 mL of ethyl acetate once. The combined organic extract was dried over anhydrous sodium sulfate, filtered and concentrated under vacuum. The crude material was dissolved in 50 mL of hot methanol and then refrigerated overnight. The crystals formed were filtered and dried under vacuum to afford 2.4 g of the desired 7-phenyl-2,4,6-heptatrienoic acid. 1H NMR (DMSO-d6, 300 MHz), δ(ppm) 7.52 (m, 2H), 7.33 (m, 4H), 7.06 (m, 1H), 6.86 (m, 2H), 6.58 (m, 1H), 5.95 (d, 1H).

Provenance & Evidence