Fluorination Triggers Fluoroalkylation: Nucleophilic Perfluoro‐tert‐butylation with 1,1‐Dibromo‐2,2‐bis(trifluoromethyl)ethylene (DBBF) and CsF

Abstract Perfluoro‐ tert ‐butylation reaction has long remained a challenging task. We now report the use of 1,1‐dibromo‐2,2‐bis(trifluoromethyl)ethylene (DBBF) as a practical reagent for perfluoro‐ tert ‐butylation reactions for the first time. Through a consecutive triple‐fluorination process with DBBF and CsF, the (CF 3 ) 3 C − species can be liberated and observed, which is able to serve as a robust nucleophilic perfluoro‐ tert ‐butylating agent for various electrophiles. The power of this synthetic protocol is evidenced by the efficient synthesis of structurally diverse perfluoro‐ tert ‐butylated molecules. Multiple applications demonstrate the practicability of this method, as well as the superiority of perfluoro‐ tert ‐butylated compounds as sensitive probes. The perfluoro‐ tert ‐butylated product was successfully applied in 1 H‐ and 19 F‐magnetic resonance imaging (MRI) experiment with an ultra‐low field (ULF) MRI system.