Enantioselective formal synthesis of tridemethylisovelleral
A simple and efficient synthetic route to the bicyclic alpha,beta-unsaturated beta-keto ester methyl (3aS,7aS)-6-oxo-2,3,3a,6,7,7ahexahydro-1H-indene-5-carboxylate, a versatile intermediate in the synthesis of biologically active unsaturated 1,4-dialdehydes, is described. The synthesis includes a chirality introducing nonenzymatic asymmetric desymmetrization (ADS) reaction of a cyclic nieso-anhydr