Ammonium formate → (R,S)-Equol

Participants

Reaction Steps

A 250-ml round bottom flask was equipped with reflux condenser, heating mantle, and magnetic stirrer, and was charged with 8.15 grams of daidzein diacetate (0.024 mole), 100 ml of acetic acid, 20 grams of ammonium formate (31 mole), and 5.0 grams of commercial Pearlman's catalyst. The mixture was stirred at relfux for 1.4 hours, at which time thin-layer chromatographic analysis indicated consumption of the starting material. The reaction mixture was cooled to room temperature, diluted with 100 ml of ethyl acetate, and filtered through a pad of diatomaceous earth filter aid. The resulting clear filtrate was poured into about 500 ml of water and shaken. The layers were allowed to separate and the top organic layer was separated, washed with water and then with 5% aqueous sodium bicarbonate solution to remove residual acetic acid. (The acetamide by-product is extracted into the water layers during this procedure.) The resulting clear solution was stripped of ethyl acetate under reduced pressure to give an off-white solid product. This material was triturated with about 15 ml of chloroform and the resulting white solid product filtered off and air-dried to afford 4.85 grams of (+/−)-equol (83.2% yield). The product was analyzed by IR and proton NMR spectroscopy and found to be of greater then 95% purity.

Provenance & Evidence