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Updated: Aug 26, 2025

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions
Published on: July 30, 2017
Apparent 6-endo-trig Carbofluorination of Alkenes Enabled by Palladium-Based Dyotropic Rearrangement
Jing Gong1, Qian Wang1, Jieping Zhu1
1Laboratory of Synthesis and Natural Products (LSPN), Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-ISIC-LSPN, BCH, 5304, 1015, Lausanne, Switzerland.
Abstract:
Alkene difunctionalization featuring an intramolecular carbometallation step has been developed into a powerful transformation in organic synthesis. The 5-exo-trig carbometallation is in general highly favored over the alternative 6-endo-trig cyclization. We report herein a formal 6-endo-trig carbofluorination protocol by combining the conventional 5-exo-trig carbopalladation with a chemoselective 1,2-aryl/Pd dyotropic rearrangement. Treatment of 2-(2-alkylallyloxy)phenyl boronic acid derivatives in the presence of a catalytic amount of Pd(dba)2 , 4,4'-di-tert-butyl-2,2'-bipyridine and Selectfluor affords chromanes with concurrent generation of a tertiary alkyl fluoride function. A σ-alkyl-PdII species resulting from the 5-exo-trig carbopalladation process is isolated and characterized by X-ray crystallographic analysis. Its oxidation to PdIV complex triggers the chemoselective dyotropic rearrangement leading to the ring expansion product.
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