Pentafluoroethylation of Carbonyl Compounds by HFC-125 <i>via</i> the Encapsulation of the K Cation with Glymes
Yamato Fujihira, Kazuki Hirano, Makoto Ono, Hideyuki Mimura, Takumi Kagawa, Daniel M. Sedgwick, Santos Fustero, Norio Shibata
Abstract
A simple protocol to overcome the explosive pentafluoroethylation of carbonyl compounds by HFC-125 is described. The use of potassium (K) bases with triglyme or tetraglyme as a solvent safely yields the pentafluoroethylation products in good to high yields. The experimental results suggest that an encapsulation of the K cation by glymes as K(glyme)2 inhibits the contact between the K cation and the reactive anionic pentafluoroethyl counterion, preventing their transformation into KF and explosive tetrafluoroethylene (TFE). The generation of sterically demanding [K(G3)2]+ and [K(G4)2]+ is an effective way as an unstable pentafluoroethyl anion reservoir.