1997 Volume 55 Issue 4 Pages 301-312
Development of efficient methods for highly selective partial fluorination of organic compounds is becoming increasingly important in various fields such as medicinal chemistry and material science. In contrast to chemical methods using flouorinating reagents, which are hazardous, difficult to handle, or very costly, electrochemical partial fluorination is an ideal method for direct fluorination since fluorine atoms can be introduced into organic molecules in one step under safe conditions. However, elctrochemical partial fluorination has not been developed owing to low selectivity for the fluorination, low nucleophilicity of fluoride ions, and passivation of electrodes.
From these viewpoints, we have developed highly selective electrochemical mono- and difluorination of organic compounds using Et3N·3HF and Et4NF·4HF as the supporting electrolyte and fluorine source. This account deals with highly selective anodic fluorination of various heteroatom compounds such as sulfides, selenides, and tellurides together with sulfur and/or nitrogen and oxygen containig heterocycles including β-lactams. Furthermore, indirect anodic mono- and gem-difluorodesulfurizations using mediators such as halogen, hypervalent fluoroiodoarenes, and triarylamines are also described. This electrochemical mehtod is much superior to conventional chemical methods because any hazardous reagents are not required and the yields are much higher compaired to the chemical methods.
