Fe-Promoted C-F Activation of Aryl Fluorides Enables Heck-Type Coupling with Alkenes and One-Pot Synthesis of Indenes

28 April 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Metal-mediated aryl fluoride activation presents challenges because of the thermodynamically robust C-F bond but also provides opportunities to develop C-C coupling reactions with this unconventional electrophile. Here, we report that the metallanucleophile, K[CpFe(CO)2] (KFp), is readily arylated by aryl fluorides to provide CpFe(CO)2Ar (FpAr) complexes at ambient conditions in the absence of any catalyst, contrary to previous literature reports. This C-F activation likely proceeds by a SNAr mechanism rather than the more common oxidative addition pathway for metal-mediated C-F cleavage. Facile access to FpAr derivatives has enabled further development of Fe-promoted coupling reactions of aryl fluorides with alkenes and alkynes. Under stoichiometric Fe conditions, the first documented examples of Heck-type coupling reactions with aryl fluoride electrophiles are reported herein. Various aryl fluorides were found to couple with olefins to provide E-alkene products; aliphatic derivatives unexpectedly underwent reduction to 1,2-disubsituted ethane products to varying extents. Aryl fluorides were also found to couple with 5-decyne to yield indene derivatives in a one-pot manner; indeneone and indanone products were also observed in selected cases. A mechanistic investigation to identify the apparently potent hydride donor generated under these conditions was conducted, leading to a mechanistic hypothesis involving the intermediacy of metal carbonyl-capped, triple-decker ferrocene compounds as reductants. Despite the involvement of these diiron intermediates limiting stoichiometric product yields, the observed C-C coupling reactions expand the limits of organofluorine chemistry.


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.