K. Wahala et al., THE SYNTHESIS, STRUCTURE, AND ANTICANCER ACTIVITY OF CIS-4',7-DIHYDROXYISOFLAVAN-4-OLS AND TRANS-4',7-DIHYDROXYISOFLAVAN-4-OLS, Journal of organic chemistry, 62(22), 1997, pp. 7690-7693
cis-4',7-Dihydroxyisoflavan-4-ol (4) and trans-4',7-dihydroxyisoflavan
-4-ol (5), two proposed metabolites of daidzein (4',7-dihydroxyisoflav
one), have been synthesized and fully characterized for the first time
. The vicinal coupling constants of the pyran ring protons are compati
ble with a half-chair conformation. The cis isomer is anancomeric whil
e the trans isomer consists of a 68:32 mixture of two ring inversion c
onformers. Molecular mechanical calculations are in agreement with the
half-chair conformation of the pyran ring and suggest that the cis is
omer is biased because of an unfavorable gauche interaction of the equ
atorial hydroxyl and the axial phenyl group. The isoflavanols 4 and 5
are comparable to genistein (4',5,7-trihydroxyisoflavone) in antitumor
activity against human prostate cancer cells.