Silver-promoted (radio)fluorination of unsaturated carbamates via a radical process
Bin Yang1, Kantapat Chansaenpak, Hongmiao Wu
1Institute of Chemistry & BioMedical Sciences, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China. hongjianlu@nju.edu.cn.
Abstract:
The intramolecular fluorocyclization of unsaturated carbamates is described here using a hypervalent iodine reagent in the presence of a silver catalyst. Both (hetero)aryl-substituted olefins and acrylamides can be utilized as effective substrates. Preliminary mechanistic investigations suggest that the reaction proceeds via a cyclization/1,2-(hetero)aryl migration/fluorination cascade involving an unusual radical process. Furthermore, starting from no-carrier-added [18F]TBAF, a simple one-pot, two-step cascade method was developed for the generation of 18F-labeled heterocycles with high radiochemical purity.
Related Concept Videos
Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene
Nucleophilic Aromatic Substitution: Elimination–Addition
Radical Reactivity: Electrophilic Radicals
Radical Substitution: Allylic Bromination
Radical Substitution: Halogenation of Alkanes and Alkyl Substituents
In the initiation step of the reaction, the chlorine molecule undergoes homolytic cleavage in the presence of light or heat, forming two highly reactive chlorine radicals. Propagation occurs in two...
Halogenation of Alkenes
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.


