Total Synthesis of (-)-Herbaric Acid through Organocatalyzed Asymmetric Halolactonization of Acrylate-Type Benzoic Acids

The total synthesis of (-)-herbaric acid has been achieved through the stereoselective synthesis of 3-substituted isobenzofuranones with a new organocatalytic route. When combined with a catalytic amount of benzoic acid, quinidine thiocarbamate based bifunctional catalysts have demonstrated their efficiency for the diastereoselective halolactonization reaction of acrylate-type benzoic acids bearing a chiral alkoxycarbonyl group on the carbon-carbon double bond. High diastereomeric excesses were obtained thanks to a positive match effect between the (+)-menthyl ester group and the chiral organocatalyst.