α-FLUORINATION OF KETONES BY XENON AND IODOBENZENE DIFLUORIDES: A STEREOCHEMICAL EVIDENCE DEMONSTRATING THEIR MECHANISTIC DIFFERENCES

Article abstract of DOI:10.1016/S0040-4039(00)87050-1

Xenon difluoride reacts smoothly with various steroid silyl enol ethers in the absence of any acid catalyst to afford stereoselectively α-oriented α-fluoroketones in good yields while iodotoluene difluoride reacts rather sluggishly with these silyl enol ethers to competitively produce β-oriented α-fluoro ketones, elimination and other nucleophilic substitution products.The observed stereochemical contrast clearly suggest an electrophilic and nucleophilic mechanism for these reactions, respectively.