A serendipitous self-assembly synthesis of CNN–Pt pincer complexes

A serendipitous one pot self-assembly synthesis of hydride CNN–Pt(iv) pincer complexes was achieved, which involves a formal C–H bond activation, with an earlier C–N bond formation via C–Br bond excision, instead of the expected rollover complex.

A novel coordination mode of κ1-N-Br-pyridylbenz-(imida, oxa or othia)-zole to Pt(ii): synthesis, characterization, electrochemical and structural analysis

Three novel platinum(ii) complexes with the general formula [trans-Pt(Br-PyBenz-X)(Cl)₂(DMSO)] containing Br-pyridylbenz(imida, oxa or othia)zole derivatives, under an unusual N-κ¹-coordination mode were synthesized.

Water-soluble SNS cationic palladium(II) complexes and their Suzuki-Miyaura cross-coupling reactions in aqueous medium

Unlike their SCS analogues, SNS pincer complexes are poorly studied for their use in coupling reactions. Accordingly, a series of water soluble cationic Pd(II) SNS pincer complexes have been successfully synthesised and investigated in detail for their catalytic activity in Suzuki-Miyaura coupling reactions. By using only 0.5 mol % loading of the complexes, the coupling of inactivated aryl bromides and activated aryl chlorides with various boronic acids in water was achieved in excellent yields and the catalysts were found to be reusable for three cycles without a significant loss of activity. The investigation of the mechanism of the reaction revealed that a Pd(II) to Pd(IV) route is the more likely pathway which was further supported by computational studies.

Carbon Dioxide-Mediated C(sp3)-H Arylation of Amine Substrates

Elaborating amines via C-H functionalization has been an important area of research over the past decade but has generally relied on an added directing group or sterically hindered amine approach. Since free-amine-directed C(sp³)-H activation is still primarily limited to cyclization reactions and to improve the sustainability and reaction scope of amine-based C-H activation, we present a strategy using CO₂ in the form of dry ice that facilitates intermolecular C-H arylation. This methodology has been used to enable an operationally simple procedure whereby 1° and 2° aliphatic amines can be arylated selectively at their γ-C-H positions. In addition to potentially serving as a directing group, CO₂ has also been demonstrated to curtail the oxidation of sensitive amine substrates.

Synthesis of 3-(2-Olefinbenzyl)-4H-chromen-4-one through Cyclobenzylation and Catalytic C-H Bond Functionalization Using Palladium(II)

An efficient strategy for synthesizing 3-(2-olefinbenzyl)-4H-chromen-4-one in two steps was developed. The first step is a cyclobenzylation reaction between (E)-3-(dimethylamino)-1-(2-hydroxyphenyl)prop-2-en-1-one and benzyl bromide to produce homoisoflavonoid. The second step involves intermolecular Pd-catalyzed π-chelating-assisted C-H bond olefination. Using the C-2/C-3 double bond of chromone, palladium-catalyzed aryl C-H bond activation can be functionalized to generate ortho-olefination derivatives in moderate to high yields.

Csp2–Br bond activation of Br-pyridine by neophylpalladacycle: formation of binuclear seven-membered palladacycle and bipyridine species

A small library of seven-membered palladacycles and asymmetric bipyridines was prepared via C–Br activation and C–C coupling reactions.

C-H Activation in Primary 3-Phenylpropylamines: Synthesis of Seven-Membered Palladacycles through Orthometalation. Stoichiometric Preparation of Benzazepinones and Catalytic Synthesis of Ureas

The dimeric cyclometalated complexes [Pd2{κ(2)C,N-C6H4CH2CH2C(R)(Me)NH2-2}2(μ-Cl)2] (R = Me (1a), H (1b)) are prepared by reacting 1,1-dimethyl-3-phenylpropylammonium or 1-methyl-3-phenylpropylammonium triflate with Pd(OAc)2 in a 1:1 molar ratio and subsequent treatment with excess NaCl. The mononuclear derivatives [Pd{κ(2)C,N-C6H4CH2CH2C(R)(Me)NH2-2}Cl(L)] (L = PPh3, R = Me (3a), H (3b); L = 4-picoline (4-pic), R = Me (4a), H (4b)) were prepared from 1a,b by splitting the chloro bridges with the neutral ligands L. A conformational analysis of the mononuclear palladacycles in solution has been carried out. Insertion of CO takes place into the Pd-C bond of complexes 1a,b, affording Pd(0) and the tetrahydro-benzazepinone 5a or 5b, which possesses potential pharmacological interest. Additionally, the triflate salt A or B undergoes catalytic carbonylation with CO to afford the corresponding N,N'-dialkylurea, using Pd(OAc)2/Cu(OAc)2, in boiling acetonitrile. The crystal structures of 3a·(1)/2H2O, 3b, 4b·CHCl3, and 5a were determined by X-ray diffraction studies.

Bis(chalcogenones) as pincer ligands: isolation and Heck activity of the selone-ligated unsymmetrical C,C,Se–Pd pincer complex

The reaction of meta-phenylene-bis(1-methyl-1H-imidazole-2(3H)-selone) with [Pd₂(μ-Cl)₂(2-C₆H₄CH₂NMe₂)₂] in dry benzene and glacial acetic acid resulted in the formation of an unsymmetrical 5,6-membered C,C,Se–Pd(ii) pincer complex.