Synthesis of Novel Hexahydroindoles from the Dearomatization of Indoline

The transiently stable indoline complex TpW(NO)(PMe₃)(η²-N-ethyl-6,7-indoline) is shown to be a synthon for a broad range of novel hexahydroindoles. The tungsten dearomatizes the indoline, allowing for its sequential protonation, electrophilic addition (e.g., protonation, fluorination, hydroxylation, acylation), nucleophilic addition (e.g., amination, arylation, etheration, alkylation), and reduction, all with well-defined and predictable stereochemistry. The tungsten stereocenter directly governs the stereoselective formation of four adjacent asymmetric carbons originating from the aromatic ring of the indoline.