Gold(I) complexes bearing a PNP-type pincer ligand: photophysical properties and catalytic investigations.

The synthesis and characterization of two dinuclear and five tetranuclear gold(I) complexes bearing the 2,6-bis(diphenylphosphinomethyl)pyridine diphosphane ligand (DPPMPY) are herein reported. The reaction between the dinuclear complexes, DPPMPY(AuCl) (1) or DPPMPY(AuBr) (2), with 1 or 2 equivalents of Ag salts yielded five tetranuclear gold(I) complexes, DPPMPYAuX (3-7), differing in the terminal ancillary ligands (X = Cl, Br, acetonitrile) and the counter ions (SbF or BF). The structures of complexes 1, 2, 3, and 5 were confirmed by single-crystal X-ray diffraction studies.

Mechanistic Studies on the Synthesis of Pyrrolidines and Piperidines via Copper-Catalyzed Intramolecular C-H Amination.

We have recently developed a method for the synthesis of pyrrolidines and piperidines via intramolecular C-H amination of -fluoride amides using [Tp CuL] complexes as precatalysts [Tp = tris(pyrazolyl)borate ligand and L = THF or CHCN]. Herein, we report mechanistic studies on this transformation, which includes the isolation and structural characterization of a fluorinated copper(II) complex, [(TpOH)CuF] [Tp = hydrotris(3,5-diisopropylpyrazolyl)borate], pertinent to the mechanistic pathway. The effects of the nature of the Tp ligand in the copper catalyst as well as of the halide in the N-X amides employed as reactants have been investigated both from experimental and computational perspectives.

Copper-catalysed radical reactions of alkenes, alkynes and cyclopropanes with N-F reagents.

The mild generation of nitrogen-centred radicals from N-F reagents has become a convenient synthetic tool. This methodology provides access to the aminative difunctionalisation of alkenes and alkynes and the radical ring-opening of cyclopropanes, among other similar transformations. This review article aims to provide an overview of recent developments of such processes involving radical reactions and N-F reagents using copper-based catalysts.

Group 11 tris(pyrazolyl)methane complexes: structural features and catalytic applications.

Tris(pyrazolyl)methane ligands (Tpm) have been for years a step behind their highly popular boron-anionic analogues, the tris(pyrazolyl)borate ligands (Tp). However, in the last decade the development of new members of this family of ligands has boosted a number of contributions albeit their use in coordination chemistry. This fact has also triggered the application of metal-Tpm complexes as catalysts for a range of organic transformations, particularly with group 11 metals.

Ruthenium-Catalyzed Heck-Type Alkenylation of Alkyl Bromides.

The complex [Cp*RuCl(PPh)] displays a high catalytic activity for the Heck-type alkenylation of alkyl bromides in the first example using this metal under thermal conditions. The coupling reaction proceeds efficiently with a variety of functionalized tertiary, secondary, and primary alkyl bromides. The presence of Hünig's base has been revealed to be crucial for this transformation.

Copper-Catalyzed N-F Bond Activation for Uniform Intramolecular C-H Amination Yielding Pyrrolidines and Piperidines.

The dual function of the N-F bond as an effective oxidant and subsequent nitrogen source in intramolecular aliphatic C-H functionalization reactions is explored. Copper catalysis is demonstrated to exercise full regio- and chemoselectivity control, which opens new synthetic avenues to nitrogenated heterocycles with predictable ring sizes. For the first time, a uniform catalysis manifold has been identified for the construction of both pyrrolidine and piperidine cores.

A versatile approach to Ullmann C-N couplings at room temperature: new families of nucleophiles and electrophiles for photoinduced, copper-catalyzed processes.

The use of light to facilitate copper-catalyzed cross-couplings of nitrogen nucleophiles can enable C-N bond formation to occur under unusually mild conditions. In this study, we substantially expand the scope of such processes, establishing that this approach is not limited to reactions of carbazoles with iodobenzene and alkyl halides. Specifically, we demonstrate for the first time that other nitrogen nucleophiles (e.

Cu(I)-catalyzed atom transfer radical cyclization of trichloroacetamides tethered to electron-deficient, -neutral, and -rich alkenes: synthesis of polyfunctionalized 2-azabicyclo[3.3.1]nonanes.

A novel synthetic entry to 2-azabicyclo[3.3.1]nonanes based on a copper(I)-catalyzed intramolecular coupling of amino-tethered trichloroacetamides and unsaturated nitriles, esters and alkenes, as well as enol acetates, is described.

Mechanistic and computational studies of the atom transfer radical addition of CCl4 to styrene catalyzed by copper homoscorpionate complexes.

Experimental as well as theoretical studies have been carried out with the aim of elucidating the mechanism of the atom transfer radical addition (ATRA) of styrene and carbon tetrachloride with a Tp(x)Cu(NCMe) complex as the catalyst precursor (Tp(x) = hydrotrispyrazolyl-borate ligand). The studies shown herein demonstrate the effect of different variables in the kinetic behavior. A mechanistic proposal consistent with theoretical and experimental data is presented.

An efficient, selective, and reducing agent-free copper catalyst for the atom-transfer radical addition of halo compounds to activated olefins.

Efficient and selective ATRA reactions of CCl(4), CBr(4), TsCl (Ts = tosyl), or Cl(3)CCO(2)Et with activated olefins (styrene, methyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate) using the Tp(tBu)Cu(NCMe) complex as a catalyst have been achieved in the absence of any reductant and with low catalyst loadings.

Copper-homoscorpionate complexes as active catalysts for atom transfer radical addition to olefins.

Cu(I) complexes containing trispyrazolylborate ligands efficiently catalyze the atom transfer radical addition (ATRA) of polyhalogenated alkanes to various olefins under mild conditions. The catalytic activity is enhanced when bulky and electron donating Tpx ligands are employed. Kinetic data have allowed the proposal of a mechanistic interpretation that includes a Cu(II) pentacoordinated species that regulates the catalytic cycle.