Synthesis of C-C-bridged bis-isoflavones

Results show that by nucleophilic substitution of the allylic bromine in 2-bromomethyl-7-4'-dimethoxyisoflavone using either ethyl cyanoacetate, or cyanide anions, or palladium-catalyzed ethoxycarbonylation, bridged bis-isoflavones can be prepared. Data indicate that a double alkylation reaction leads to the formation of bis-isoflavones.