Calcium-Catalyzed Asymmetric Benzoyloxylation of 3-Aryloxindoles

Significance

The authors describe an asymmetric benzoyloxylation of 3-aryl-2-oxindoles in the presence of a chiral VAPOL calcium phosphate salt. The 3-hydroxy-2-oxindole products bearing quaternary stereogenic centers can be obtained with excellent enantioselectivities and yields. A similar calcium catalyst was reported by Ishihara’s group (Hatano et al. Angew. Chem. Int. Ed. 2010, 49, 3823), and this type of calcium phosphate salt chemistry has become an important addition to metal salt chemistry.