Bis-triethylene Glycolic Crown-5-calix[4]arene: A Promoter of Nucleophilic Fluorination Using Potassium Fluoride

Abstract

We designed and synthesized a bis-triethylene glycolic crown-5-calix[4]arene (BTC5A) as a multifunctional promoter for nucleophilic fluorination using KF. The synergetic effect of the calix-crown moiety and ethylene glycols of BTC5A enabled KF to be easily dissolved in organic solvents and activated the fluoride in even nonpolar aprotic media. To validate its practicality, the S_N2 fluorinations including ¹⁸F-fluorination of various substrates were successfully conducted using KF(or [¹⁸F]F^-) in the presence of BTC5A.