Stereoselective Synthesis of Spirooxindoles by Palladium-Catalyzed Decarboxylative Cyclization of γ-Methylidene-δ-valerolactones with Isatins

A new synthetic method of spirooxindole derivatives has been developed by way of a palladium-catalyzed decarboxylative cyclization of gamma-methylidene-delta-valerolactones with isatins. By employing a newly prepared phosphoramidite ligand, the reaction proceeds smoothly with excellent diastereoselectivity. Preliminary results of its application to asymmetric catalysis using a chiral phosphoramidite ligand are also described.