Palladium‐Mediated Fluorination of Arylboronic Acids

Abstract

Saving the best for last: Novel palladium complexes allow mild, two‐step fluorination of aryl boronic acids (see scheme). The reaction is regiospecific, functional‐group tolerant, has a broad substrate scope, and is ideally suited for the introduction of fluorine substituents at a late stage for aryl fluoride synthesis.

Synthesis of fluorinated oxygen- and sulfur-containing heteroaromatics

“…using novel palladium complexes [29,30]. These palladium complexes incorporate nitrogenous, bidentate ligands which resist oxidation by electrophilic fluorination reagents, can support high-valence aryl palladium fluorides for subsequent carbon-fluorine reductive elimination and do not induce competing nitrogen-fluorine reductive elimination.…”

Activation and Formation of Aromatic C–F Bonds

“…In 2008, they reported aryl palladium complexes that were able to mediate the fluorination of aryl boronic acids using Selectfluor™ (Scheme 3) [26]. This method is highly regioselective even without a directing group and does not involve harsh reaction conditions.…”

“…Holland and colleagues demonstrated C-F activation of fluorobenzene using a cobalt diketiminate-supported complex (26) to give a Co-F species (27) N.A. LaBerge and J.A.…”

Transition Metal-Mediated and Metal-Catalyzed Carbon–Fluorine Bond Formation

“…In 2008, the Ritter group reported a regioselective fluorination of arylboronic acids using Selectfluor and a stoichiometric palladium complex (Fig. 59) [88,89,151]. The two-step reaction sequence proceeded by transmetallation of the arene substrate from boron to palladium, followed by oxidation to afford the aryl fluoride product.…”

“…3.2.1), a key challenge for metal-catalyzed fluorination of arylboronic acid derivatives is the slow transmetallation of the arene from boron to the transition metal catalyst under conditions that are suitable for fluorination [151]. For the Pd-catalyzed fluorination of arylboronic acid derivatives, mechanistic studies indicate a catalysis cycle that does not involve transmetallation to form an arylpalladium intermediate.…”