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DOI: 10.1055/s-0033-1340728
Trisubstituted Monofluoroalkenes via Rh-Catalyzed Allylic C–F Bond Activation
Publication History
Publication Date:
17 February 2014 (online)

Significance
Fluorinated organic molecules are of particular interest to the pharmaceutical, agrochemical, and polymer industry as a consequence of the unique properties of carbon–fluorine bonds, where the replacement of C–H or C–OH bonds is usually exploited to adjust acidity, lipophilicity, and (metabolic) stability. As a result, new methodologies to introduce fluorine into complex organic molecules are necessary to satisfy the continuously growing demand. Herein, the authors report the stereoselective synthesis of trisubstituted monofluoroalkenes via a rhodium-catalyzed Csp3–F bond activation of allylic difluorohomoallylic alcohols.
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Comment
Under the optimized conditions, the reaction exhibited a substrate scope that included aromatic and heteroaromatic substituents. Interestingly, the selectivity of the reaction depends strongly on the electronic nature of the substituents, where reactions of halogen-, ester-, and sulfonate-substituted substrates have furnished the Z-configured products with selectivities up to >99:1. Initial mechanistic studies were conducted and support a C–F activation mode. However, isomerization studies have also shown that the stereoselectivity is controlled predominately by Ph3P via a rhodium-independent pathway.
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Review
For an account on C(sp3)–F activation, see: M. F. Kuehnel, D. Lentz, T. Braun Angew. Chem. Int. Ed. 2013, 52, 3328–3348.
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