A Direct Synthesis of 2‐(ω‐Carboxyalkyl)isoflavones from ortho‐Hydroxylated Deoxybenzoins

As part of a program focused on the development of new antineoplastic agents based on scaffolds found in natural products, we explored the isoflavone family as potential enzyme inhibitors. We required biotin-modified isoflavones to identify potential biological targets, and we selected the C-2 position in isoflavones as an attachment site for an alkyl group bearing a terminal carboxylic acid to which we could attach a biotin derivative. The base-catalyzed condensation of 2,4-dihydroxy-substituted deoxybenzoins with cyclic anhydrides mediated by a combination of triethylamine and 1,8-diazabicyclo[5.4.0]undec-7-ene led to an efficient synthesis of the desired 2-(-carboxyalkyl)isoflavones with functional groups at C-5, 6 and 7 and with various substituents in the C-3 phenyl group.