Stereocontrolled Nucleophilic Fluorination at the Tertiary sp(3)-Carbon Center for Enantiopure Synthesis of 3-Fluorooxindoles

The first asymmetric nucleophilic fluorination at the sp(3)-tertiary carbon center has been developed using inexpensive tetrabutylammonium fluoride (TBAF) without any metal/catalyst for the synthesis of 3-fluoro-3-substituted oxindoles with excellent enantioselectivity (ee up to >99%). Regio- and stereocontrolled ring opening of spiroaziridine with retention of configuration and other experiments revealed that the fluorination proceeded through an anchimeric assistance.