Total synthesis and structure determination of ephedroidin.

The total synthesis and structure determination of enantiomerically pure (+)- and (-)-ephedroidin from the leguminous plant, is described. (+)- and (-)-Ephedroidin were a flavonoid with a chiral secondary alcohol on a side chain derived from a prenyl group. These compounds were obtained by optical resolution of (±)-ephedroidin through α-methoxyphenylacetic acid (MPA) esterification. The racemic secondary hydroxy group of (±)-ephedroidin was generated by photooxidation of prenylated flavonoid. Based on the total synthesis and Trost's method using α-methoxyphenylacetic acid (MPA) ester derivatives, the absolute configurations of (+)- and (-)-ephedroidin were revealed.