Phase-transfer catalyzed synthesis of the Soy isoflavanoid S-Equol

S-Equol is an isoflavanoid metabolized from the isoflavone daidzein by intestinal bacteria. Only 30-50 percent of all individuals possess bacteria that produce S-Equol. Recent data supports the compound’s pharmaceutical potential for treating prostate cancer and post-menopausal estrogen deficiency (ref. 1). Because the compound is only minutely available from natural sources, an affordable asymmetric total synthesis would be necessary to generate sufficient quantities for expanded research. Only one asymmetric total synthesis of S-Equol has been reported to date, using a chiral auxiliary to give product in a 10 percent yield over 6 steps (ref. 2). It is our goal to develop an improved asymmetric synthesis of S-Equol, and thereby obtain sufficient quantities for biological testing