A New Approach to the Synthesis of Isoflavones, 2'-Hydroxyisoflavones and an Alternative Synthesis of (±)-Pteroicarpin

A new approach to the synthesis of isoflavones and 2'-hydroxyisoflavones, useful inter-mediates for synthesis of pterocarpinoids, are described. The 2'-hydroxyisoflavone (VIII; R=CH3, R'=H) synthesized by this method, was converted into (±)-pterocarpin (VII; R=CH3, R'=H). Attempts to obtain the corresponding isoflavane or isoflavene from the coumarine (XVII) failed.