Facile and General Synthesis of Quaternary 3-Aminooxindoles

A novel approach to the valuable quaternary 3-aminooxindole skeleton is reported on the basis of intramolecular arylation of enolates of substituted amino acids. The reaction tolerates dialkyl- and arylalkylamines as well as a range of carbon substituents (primary and secondary alkyl, aryl). The cyclization of N-indolyl-substituted substrates is accompanied by direct C−H arylation of the indole, leading to indolo-fused benzodiazepines.