(+)-Pisatin biosynthesis: From (−) enantiomeric intermediates via an achiral 7,2′-dihydroxy-4′,5′-methylenedioxyisoflav-3-ene

The synthesis of (+)-pisatin, a pterocarpanoid phytoalexin made by peas, and (−)-pterocarpans use some of the same (−)-intermediates. This study demonstrated that a (−)-isoflavanone [(−)-sophorol] is converted to a cis-(−)-isoflavanol [cis-(−)-DMDI] that is converted to an achiral isoflavene, which is proposed to begin the conversion of intermediates to the (+)-stereochemistry.