Synthesis of enantiopure concave (+)-avenaciolide and (−)-canadensolide skeletons

Simultaneous regio- and chemoselective reduction of the carboxyl group of (2S,3S)-tetrahydro-3-hydroxy-5-oxo-2,3-furandicarboxylic acid (garcinia acid), isolated from plant sources in large amounts, has been carried out to reach the core concave bislactone structures of fungal metabolites (+)-avenaciolide and (−)-canadensolide in one and two steps, respectively.