Abstract
Organofluorine compounds are highly useful in various fields such as material science, medicinal chemistry, and theoretical chemistry. As a novel synthetic method of organofluoro compounds, we have established electrochemical partial fluorination, which can be carried out without any hazardous reagents under mild conditions. However, these electrochemical fluorinations are not always easy due to the low nucleophilicity of fluoride ions and anode passivation. On the other hand, ultrasonic effects on electrochemical processes have received much interest, since the product yield and selectivity in the processes are greatly affected by promotion of mass transport caused by a cavitational micro-jet stream. Moreover, the micro-jet stream can also clean the electrode surface. From the above viewpoint, effects of ultrasound on the anodic fluorination of ethyl α-phenylthio acetate in an organic solvent were examined in this work. The yield and selectivity for the α-monofluorinated product was greatly increased by ultrasonication. This ultrasonic effect could be rationalized in term of mass-transport promotion of the substrate by the sonication. In addition, it was also demonstrated that the ultrasonication greatly increased the yield and selectivity in anodic fluorination of 3-methyl-2-phenyl-4-thiazolidinone in Et_3N-3HF ionic liquid, as shown in Table 1. Tablel Anodic fluorination of 3-methyl-2-phenyl-4-thiazolidinone in Et_3N-3HF ionic liquid[figure]
