Room Temperature Catalyst System for the Hydroarylation of Olefins

A simple protocol for the hydroarylation of olefins to yield diarylmethine products is described. A Friedel–Crafts-type synthetic strategy allows direct access to biorelevant products in high atom efficiency. A combination of substoichiometric amounts of TMSCl and ZnBr₂ promotes a rapid hydroarylation process at ambient temperature. The method is high yielding and is amenable to scale-up protocols

Ni-Catalyzed Enantioselective <i>C</i>‑Acylation of α‑Substituted Lactams

A new strategy for catalytic enantio­selective <i>C</i>-acylation to generate α-quaternary-substituted lactams is reported. Ni-catalyzed three-component coupling of lactam enolates, benzo­nitriles, and aryl halides produces β-imino lactams that then afford β-keto lactams by acid hydrolysis. Use of a readily available Mandyphos-type ligand and addition of LiBr enable the construction of quaternary stereo­centers on α-substituted lactams to form β-keto lactams in up to 94% ee

Metal Ion Complexes of <i>N,N</i>′‑Bis(2-Pyridylmethyl)-<i>trans</i>-1,2-Diaminocyclohexane-<i>N,N</i>′‑Diacetic Acid, H₂bpcd: Cis/Trans Isomerization Equilibria

The synthesis of <i>N,N</i>′-bis­(2-pyridylmethyl)-<i>trans</i>-1,2-diaminocyclohexane-<i>N,N</i>′-diacetic acid (H₂bpcd) and its complexation of Ga­(III) and Co­(III) are reported. H₂bpcd and the metal–bpcd^2– complexes, isolated as hexafluorophosphate salts, were characterized by elemental analysis, X-ray crystallography, IR spectroscopy, and ¹H and ¹³C NMR spectroscopy. [Ga­(bpcd)]­PF₆, [Ga­(C₂₂H₂₆N₄O₄)]­PF₆, crystallized in the orthorhombic space group <i>Ibca</i>, with <i>a</i> = 13.8975(7) Å, <i>b</i> = 15.0872(7) Å, <i>c</i> = 22.2418(10) Å, and <i>Z</i> = 8. Ga is coordinated in a distorted octahedral geometry provided by a N₄O₂ donor atom set with <i>trans</i>-monodentate acetate groups and <i>cis</i>-2-pyridylmethyl N atoms, i.e., the <i>trans</i>-O,O isomer. The diamagnetic [Co­(bpcd)]­PF₆, [Co­(C₂₂H₂₆N₄O₄)]­PF₆, also crystallized from solution in the <i>Ibca</i> space group as the <i>trans</i>-O,O isomer. The ¹H and ¹³C assignments for H₂bpcd and metal–bpcd^2– complexes were made on the basis of 2D COSY and HSQC experiments, which were used to differentiate among three possible isomers, i.e., one cis (<i>C</i>₁ symmetry) and two trans (<i>C</i>₂ symmetry). NMR results indicate that the [Ga­(bpcd)]⁺, [Co­(bpcd)]⁺, and <i>cis</i>-O,O, <i>cis</i>-N_py,N_py-[Ga­(bppd)]⁺ cations, where bppd^2– stands for bis­(2-pyridylmethyl)-1,3-diaminopropane diacetate, are present in solution as isomers with the same symmetry as observed in the solid state. The crystallographic data and the dramatic shift that occurs in the position of the cis/trans isomerization equilibria for the [Ga­(bpad)]⁺ cations simply by increasing the number of bridging CH₂ groups in the ligand’s diamine backbone represent a unique opportunity to assess the accuracy of modern computational methods. The performance of several local density functionals using a pseudopotential-based SDD basis set was compared with the more rigorous HF and MP2 ab initio calculations. The SVWN5 and SV5LYP functionals provide significantly better Ga–O and Ga–N distances than the HF method or the nonlocal BLYP functional. However, to provide proper isomerization energies the pseudopotential-DFT calculations must be augmented by MP2 single-point energies and calculations of solvation free energies