Anomalous chiroptical properties of warfarin and phenprocoumon

The configurationally similar enantiomers of warfarin and phenprocoumon are found to exhibit circular dichroism curves which are nearly mirror related in the range of 240-340 nm. This effect is interpreted as being due to spatial similarities of the preferred conformations of opposite configurations of the two drugs in solution. An inherently dissymmetric chromophore (theta approximately 1.2 x 10(5)) is observed at approximately 220 nm for warfarin, the cyclic hemiketal tautomeric forms, and the cyclic methyl ketals.