Organocatalytic enantioselective tandem Michael addition-oxidation of 3-substituted oxindoles with 1,4-benzoquinone

By employing a chiral bifunctional thiourea-tertiary amine as catalyst, enantioselective tandem Michael addition-oxidation of 3-monosubstituted oxindoles with 1,4-benzoquinones were realized. The reactions afforded a wide range of 3,3-disubstituted oxindoles with moderate to good yields (up to 87%) in moderate to good enantioselectivities (up to 96%).