Ligand Control of Diastereodivergency in Asymmetric Inverse Electron Demand Diels-Alder Reaction

A diastereodivergent direct catalytic asymmetric inverse electron demand Diels-Alder reaction between ketenes and 3-alkylenyloxindoles was accomplished by using chiral N,N'-dioxide/gadolinium complexes. By adjusting only the substituents of the ligand and retaining other catalysis conditions, both syn- and anti-indole-fused dihydropyranones bearing two vicinal stereogenic centers were obtained in high yields with excellent ee values. Thus, by changing the configuration of the chiral ligands, all stereoisomers could be obtained from the same set of starting materials.