Selective Activation of Fluoroalkenes with N‐Heterocyclic Carbenes: Synthesis of N‐Heterocyclic Fluoroalkenes and Polyfluoroalkenyl Imidazolium Salts |
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Authors: | Matthew C Leclerc Dr Serge I Gorelsky Bulat M Gabidullin Ilia Korobkov Prof R Tom Baker |
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Institution: | Department of Chemistry and Biomolecular Sciences and Centre for Catalysis Research and Innovation, University of Ottawa, Ottawa, Ontario, Canada |
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Abstract: | Selective reactions between nucleophilic N,N′‐diaryl‐heterocyclic carbenes (NHCs) and electrophilic fluorinated alkenes afford NHC fluoroalkenes in high yields. These stable compounds undergo efficient and selective fluoride abstraction with Lewis acids to give polyfluoroalkenyl imidazolium salts. These salts react at Cβ with pyrrolidine to give ammonium fluoride‐substituted salts, which give rise to conjugated imidazolium‐enamine salts through loss of HF. Alternatively, reaction with 4‐(dimethylamino)‐pyridine provides a Cα‐pyridinium‐substituted NHC fluoroalkene. These compounds were studied using multinuclear NMR spectroscopy, mass spectrometry, and X‐ray crystallography. Insight into their electronic structure and reactivity was gained through the use of DFT calculations. |
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Keywords: | carbenes fluoroalkenes imidazolium NMR spectroscopy pyrrolidine |
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