Mechanistic insight into the thermal activation of Togni's trifluoromethylation reagents
Nico Santschi1, Benson J Jelier, Thomas Nauser
1Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology (ETH) - Zürich, Vladimir-Prelog-Weg 1, CH-8093 Zürich, Switzerland. snico@inorg.chem.ethz.ch.
Abstract:
Herein we investigate the propensity of hypervalent iodine based electrophilic trifluoromethylating agents to undergo thermally induced fragmentation of the F3C-I-O motif. For the first time we are able to observe a dissociative electron transfer mechanism using mass spectroscopy techniques to generate and trap CF3 radicals. Consistent with this mechanism, alkyl radical elimination from these reagents is in full support of an intermediate cyclic iodanyl radical and a reagent-specific temperature of maximum radical production was found to correlate with reported solution phase reactivity.
Related Concept Videos
Cycloaddition Reactions: MO Requirements for Thermal Activation
Cycloaddition Reactions: MO Requirements for Photochemical Activation
Radical Substitution: Hydrogenolysis of Alkyl Halides with Tributyltin Hydride
The bonds formed in this reaction are stronger than the bonds broken, making it energetically favorable. The reaction follows a radical chain mechanism similar to radical halogenation reactions,...
Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene
Radical Halogenation: Thermodynamics
Aldehydes and Ketones to Alkenes: Wittig Reaction Mechanism
The reaction begins with the nucleophilic addition between a phosphorus ylide and the carbonyl compound. Due to its carbanionic character, phosphorus ylide acts as a strong nucleophile and attacks the electrophilic carbonyl group. This generates a charge-separated dipolar intermediate called betaine. The negatively charged oxygen atom and...


