This report describes a method for the deoxyfluorination of phenols with sulfuryl fluoride (SOF) and tetramethylammonium fluoride (NMeF) via aryl fluorosulfonate (ArOFs) intermediates. We first demonstrate that the reaction of ArOFs with NMeF proceeds under mild conditions (often at room temperature) to afford a broad range of electronically diverse and functional group-rich aryl fluoride products. This transformation was then translated to a one-pot conversion of phenols to aryl fluorides using the combination of SOF and NMeF. Ab initio calculations suggest that carbon-fluorine bond formation proceeds via a concerted transition state rather than a discrete Meisenheimer intermediate.

This Communication describes the Cu(OTf)2-mediated fluorination of aryltrifluoroborates with KF. The reaction proceeds under mild conditions (at 60 °C over 20 h) and shows a broad substrate scope and functional group tolerance. The Cu is proposed to play two separate roles in this transformation: (1) as a mediator for the aryl–F coupling and (2) as an oxidant for accessing a proposed Cu(III)(aryl)(F) intermediate.

The insertion of an unsaturated ligand into a MC or MH bond proceeds through migratory insertion, a fundamental organometallic reaction. Recent literature documents evidence of the migratory insertion of alkenes into an MO and MN bonds for alkene alkoxylation and alkene amination reactions, respectively. Herein we provide an overview of the literature and a perspective on how these recent experiments relate to classic experiments on CO and CN bond formation with alkene complexes of the late transition metals.

We report a detailed examination of the effect of the steric and electronic properties of the ancillary ligand and the alkene reactant on the rate of migratory insertion of unactivated alkenes into the palladium-nitrogen bond of isolated palladium amido complexes. A series of THF-bound and THF-free amidopalladium complexes ligated by cyclometalated benzylphosphine ligands possessing varied steric and electronic properties were synthesized. The THF-free complexes react with ethylene at -50 °C to form olefin-amido complexes that were observed directly and that undergo migratory insertion, followed by β-hydride elimination to generate enamine products. The effect of the steric properties of the ancillary ligand on the binding of the alkene and the rate of migratory insertion were evaluated individually. The relative binding affinity of ethylene vs THF is larger for the less sterically hindered complex than for the more hindered complex, but the less hindered complex undergoes the insertion of ethylene more slowly than does the more hindered complex. These two changes in relative equilibrium and rate constants cause the rates of reaction of ethylene with the two THF-ligated species having different steric properties to be similar to each other. Reactions of the complexes containing electronically varied ancillary ligands showed that the more electron-poor complexes underwent the migratory insertion step faster than the more electron-rich complexes. Reactions of a THF-ligated palladium-amide with substituted vinylarenes showed that electron-poor vinylarenes reacted with the amido complex slightly faster than electron-rich vinylarenes. Separation of the energetics of binding and insertion indicate that the complex of an electron-rich vinylarene is more stable in this system than the complex of a more electron-poor vinylarene but that the insertion step of the bound, electron-rich vinylarene is slower than the insertion step with the bound, electron-poor vinylarene.

Herein are reported examples of the nickel-and palladium-catalyzed cross-coupling of aryl fluorosulfonates and boronic acids. These reactions occur in good to excellent yields under mild conditions with excellent functional group compatibility employing either Pd(OAc) 2 and inexpensive PPh 3 or the inexpensive and readily available NiCl 2 (PCy 3 ) 2 . Importantly, the in situ conversion of phenol derivatives to the corresponding aryl fluorosulfonate by reaction with sulfuryl fluoride and a base, and subsequent cross-coupling to form biaryls in a single pot are described. The combination of inexpensive sulfuryl fluoride and efficient catalysts reported in these methodologies will enable economical Suzuki coupling of phenols in pharmaceutical and agrochemical processes. Transition metal catalyzed cross-coupling methodologies to form new carbon-carbon or carbon-heteroatom bonds have revolutionized modern organic synthesis. 1 The Suzuki-Miyaura coupling of an aryl boronic acid or ester with an aryl halide to form a new C(sp 2 )-C(sp 2 ) bond is a reliable, economical reaction that has been incorporated into processes for the preparation of specialty, agricultural, and pharmaceutical chemicals. 2 Aryl electrophiles derived from phenols offer an alternative to aryl halides in crosscoupling reactions. 3,4 Couplings of aryl triflates have been described for over two decades; 5 however the high cost of triflic anhydride has limited the practice of this chemistry to only the most high-value materials. Recent advances with Pd 6 and Ni 7 catalysts have allowed for the coupling of aryl mesylates and tosylates with boronic acid derivatives. Nickel-catalyzed Suzuki couplings of aryl pivalates, carbamates and sulfamates 8 have also been reported, but these systems typically require expensive, complex ligands or harsh conditions that continue to limit the utility of these methods. Scheme 1. Preparation of Aryl Fluorosulfonates from Phenols and Sulfuryl FluorideAryl fluorosulfonates were first described more than 4 decades ago, but the chemistry of these compounds is relatively unexplored. 9 Recently, renewed interest in the preparation of aryl fluorosulfonates from the reaction of a phenol with sulfuryl fluoride in the presence of a base was described by Sharpless and coworkers (Scheme 1). 10 Sulfuryl fluoride (SO 2 F 2 , bp = -55.4 °C) is produced by Dow AgroSciences, LLC, and is most commonly employed as a commodity insecticide for the control of drywood termites by whole-structure fumigation. 11 Examples of palladium-catalyzed functionalization reactions of aryl and vinyl fluorosulfonates are scarce, 12 and the relative propensity of fluorosulfonates to undergo oxidative addition to palladium, compared to more well-studied aryl sulfonates and aryl halides, has not been reported.Herein, we report the first detailed examination of the crosscoupling of aryl fluorosulfonates with aryl boronic acids catalyzed by the combination of either a palladium or nickel complex and phosphine ligand. 13 The reaction is promoted by a broad set...

We report a series of palladium diarylamido complexes containing a cyclometalated phosphine ligand and a coordinated THF that form enamine products from migratory insertion of ethylene and octene into the metal-nitrogen bond. The reactions of these complexes were sensitive to the electronic properties of the diarylamido group. The complex with the more electron-donating amido ligand reacted nearly 2 orders of magnitude faster than the complex with the least electron-donating amido group. The mechanism of the reactions with alkenes involves exchange of olefin for THF, as revealed by the positive order of the reaction in alkene and inverse order in the concentration of THF. A syn-aminopalladation that would result from migratory insertion was revealed by the stereochemistry of the enamine product resulting from reaction with cis-ethylene-d(2). Finally, a three-coordinate THF-free species was isolated from a synthesis of the amido complex in aromatic solvents, and spectroscopic evidence for an ethylene amido species was gained, in part by the addition of H(2)(13)C=(13)CH(2) to the three-coordinate amido complex at -100 degrees C.

Examples of the palladium- and nickel-catalyzed amination of aryl fluorosulfonates with aromatic and alkyl amines are described. Aniline is coupled to a diverse series of aryl fluorosulfonates catalyzed by the combination of CpPd­(cinammyl) and Xantphos, and the relative reactivity of aryl fluorosulfonates to undergo Pd-catalyzed amination was compared with other common aryl electrophiles. In addition, we report the direct amination of a phenol by in situ formation of an aryl fluorosulfonate by reaction with sulfuryl fluoride and base followed by subsequent amination to form a new C–N bond. Finally, we report examples of the nickel-catalyzed amination of aryl fluorosulfonates catalyzed by the combination of Ni­(COD)2 and DPPF in the presence of MeCN. The high reactivity of the aryl fluorosulfonate electrophile with generic palladium and nickel catalyst systems, combined with its simple preparation from sulfuryl fluoride will enable commercial amination reactions of abundant phenolic raw materials.

We report the formation of phosphine-ligated alkylpalladium(II) amido complexes that undergo reductive elimination to form alkyl-nitrogen bonds and a combined experimental and computational investigation of the factors controlling the rates of these reactions. The free-energy barriers to reductive elimination from t-BuP-ligated complexes were significantly lower (ca. 3 kcal/mol) than those previously reported from NHC-ligated complexes. The rates of reactions from complexes containing a series of electronically and sterically varied anilido ligands showed that the reductive elimination is slower from complexes of less electron-rich or more sterically hindered anilido ligands than from those containing more electron-rich and less hindered anilido ligands. Reductive elimination of alkylamines also occurred from complexes bearing bidentate P,O ligands. The rates of reactions of these four-coordinate complexes were slower than those for reactions of the three-coordinate, t-BuP-ligated complexes. The calculated pathway for reductive elimination from rigid, 2-methoxyarylphosphine-ligated complexes does not involve initial dissociation of the oxygen. Instead, reductive elimination is calculated to occur directly from the four-coordinate complex in concert with a lengthening of the Pd-O bond. To investigate this effect experimentally, a four-coordinate Pd(II) anilido complex containing a flexible, aliphatic linker between the P and O atoms was synthesized. Reductive elimination from this complex was faster than that from the analogous complex containing the more rigid, aryl linker. The flexible linker enables full dissociation of the ether ligand during reductive elimination, leading to the faster reaction of this complex.