Taming Radical Intermediates for the Construction of Enantioenriched Trifluoromethylated Quaternary Carbon Centers.

Demonstrated herein is the construction of trifluoromethylated quaternary carbon centers by an asymmetric radical transformation. Enantioenriched trifluoromethylated oxindoles were accessed using a hypervalent iodine‐based trifluoromethyl transfer reagent in combination with a magnesium Lewis acid catalyst and PyBOX‐type ligands to achieve up to 99 % ee and excellent chemical yields. Mechanistic studies were performed by experimental and computational methods and suggest a single‐electron transfer induced SN2‐type mechanism. This example is thereby the first report on the construction of enantioenriched trifluoromethylated carbon centers using hypervalent iodine‐based reagents proceeding through such a reaction pathway. Taming the CF3 radical: A unique single‐electron transfer (SET) induced SN2‐type reaction enables the construction of enantioenriched trifluoromethylated oxindoles using a hypervalent iodine‐based trifluoromethyl transfer reagent. A combination of magnesium Lewis acid catalysis and PyBOX‐type ligands successfully tames the highly reactive CF3 radical to achieve excellent enantioselectivities. [ABSTRACT FROM AUTHOR]