Magnesium-Catalyzed Electrophilic Trifluoromethylation: Facile Access to All-Carbon Quaternary Centers in Oxindoles

5 years ago

Magnesium-Catalyzed Electrophilic Trifluoromethylation: Facile Access to All-Carbon Quaternary Centers in Oxindoles

Dmitry Katayev, Harutake Kajita, Antonio Togni

The first example of a magnesium-catalyzed direct trifluoromethylation of 3-substituted oxindoles using an electrophilic hypervalent iodine reagent is reported. The reaction proceeds under unprecedented mild conditions leading to the formation of an all-carbon quaternary center in oxindoles in high chemical yield and demonstrates excellent functional group tolerance. In addition to trifluoromethyl, other perfluoroalkyl groups can be introduced with similar level of efficacy. Mechanistic investigations are consistent with the involvement of a radical pathway. The chemical versatility of the obtained products is further illustrated through their conversion in situ into valuable organofluorine building blocks, making the protocol more widely applicable. Magnesium magic: The first magnesium-catalyzed direct perfluoroalkylation of 3-substituted oxindoles using an electrophilic hypervalent iodine reagent is described. This simple protocol offers rapid access to oxindoles containing an all-carbon quaternary center in high chemical yield and displays excellent functional group compatibility. Enantiomerically enriched C3-trifluoromethylated oxindoles can be also generated using chiral ligands. The trifluoromethylated products were further converted into a series of organofluorine building blocks by one-pot, multistep transformations.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/chem.201700851