Suzuki-Miyaura Cross-Coupling Reaction Using Palladium Catalysts Supported on Phosphine Periodic Mesoporous Organosilica.

Phosphine periodic mesoporous organosilicas (R-P-PMO-TMS: R=Ph, tBu), which possess electron-donating alkyl substituents on the phosphorus atom, were synthesized using bifunctional compounds with alkoxysilyl- and phosphino groups, bis[3-(triethoxysilyl)propyl]phenylphosphine borane (1 a) and bis[3-(triethoxysilyl)propyl]-tert-butylphosphine borane (1 b). Immobilization of Pd(0) species was performed to give R-P-Pd-PMO-TMS: R=Ph (2 a), tBu (3 a), respectively. The Pd(0) immobilized 2 a and 3 a were applicable as catalysts for Suzuki-Miyaura cross-coupling reactions of aryl chlorides with phenylboronic acid. It was revealed that 3 a bearing more electron-donating tBu groups exhibited higher catalytic activity. Various functional groups including both electron withdrawing and donating substituents were compatible in the system. The recyclability of 3 a was examined to support its moderate utility for the recycle use.

Ester hydrogenolysis via ß-C-O bond cleavage catalysed by a phenanthroline-based PNNP-cobalt(I) complex.

A Co(I) catalyst bearing a phenanthroline-based PNNP ligand (2,9-bis((diphenylphosphanyl)methyl)-1,10-phenanthroline) exhibits long-range metal ligand cooperation behavior using a ligand backbone as a hydrogen reservoir and catalyses hydrogenolysis of benzyl benzoate derivatives via ß-C-O cleavage with atmospheric pressure H2.

Drug-induced entero-colitis due to interleukin-17 inhibitor use; capsule endoscopic findings and pathological characteristics: A case report.

BACKGROUND: Interleukin-17 (IL-17) inhibitors are known to cause exacerbation or new onset of inflammatory bowel disease upon administration. However, few reports have described characteristic endoscopic and histopathologic findings, and no small intestinal lesions have been reported so far. CASE SUMMARY: A woman in her 60s with psoriasis was administered ixekizumab (IXE), an anti-IL-17A antibody, for the treatment of psoriasis. Twenty months after commencing treatment, the patient visited our hospital because of persistent diarrhea. Blood tests performed at the time of the visit revealed severe inflammation, and colonoscopy revealed multiple round ulcers throughout the colon. A tissue biopsy of the ulcer revealed infiltration of inflammatory cells and granuloma-like findings in the submucosal layer. Capsule endoscopy revealed multiple jejunal erosions. After the withdrawal of IXE, the symptoms gradually improved, and ulcer reduction and scarring of the colon were endoscopically confirmed. CONCLUSION: To the best of our knowledge, 17 reports have documented IL-17 inhibitor-induced entero-colitis with endoscopic images, endoscopic findings, and pathological characteristics, including the present case. Nine of these cases showed diffuse loss of vascular pattern, coarse mucosa/ulcer formation in the left colon, and endoscopic findings similar to those of ulcerative colitis. In the remaining eight cases, discontinuous erosions and ulcerations from the terminal ileum to the rectum were seen, with endoscopic findings similar to those of Crohn's disease. In this case, the findings were confirmed by capsule endoscopy, which has not been previously reported.

Oxidative Depolymerization of Polyphenylene Oxide into Benzoquinone.

Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) is one of the most important engineering plastics commonly utilized in various fields. Herein, chemical recycling of PPO was performed via oxidative depolymerization to form 2,6-diemthyl-p-benzoquionone (26DMBQ) as a sole aromatic product in 66 % yield using nitronium ions (NO2 + ) as a mild oxidant. Mechanistic studies revealed that PPO is oxidized by NO2 + generated from the combination of a silicotungstic acid and nitrate salts, and then subsequently attacked by H2 O to achieve C-O bond cleavage, resulting in the formation of 26DMBQ, which was sublimed at the headspace of the reaction vessel in pure form. 26DMBQ was applied to polymerization with dianilines to form polyimides. Thus, an upgrade recycling process of PPO was demonstrated.

Square-Planar Anionic Pt0 Complexes.

A T-shaped Pt0 complex with a diphosphine-borane (DPB) ligand was prepared. The Pt→B interaction enhances the electrophilicity of the metal and triggers the addition of Lewis bases to give the corresponding tetracoordinate complexes. For the first time, anionic Pt0 complexes are isolated and structurally authenticated. X-ray diffraction analyses show the anionic complexes [(DPB)PtX]- (X=CN, Cl, Br, I) to be square-planar. The d10 configuration and Pt0 oxidation state of the metal were unambiguously established by X-ray photoelectron spectroscopy and DFT calculations. The coordination of Lewis acids as Z-type ligands is a powerful mean to stabilize elusive electron-rich metal complexes and achieve uncommon geometry.

Hydrogen peroxide production from oxygen and formic acid by homogeneous Ir-Ni catalyst.

Hydrogen peroxide was directly produced from oxygen and formic acid, catalysed by a hetero-dinuclear Ir-Ni complex with two adjacent sites, at ambient temperature. Synergistic catalysis derived from the hetero-dinuclear Ir and Ni centres was demonstrated by comparing its activity to those of the component mononuclear Ir and Ni complexes. A reaction intermediate of Ir-hydrido was detected by UV-vis, ESI-TOF-MS, and 1H NMR spectroscopies. It was revealed that the Ir moiety serves as an active species of Ir-hydrido, reacting with oxygen to afford an Ir-hydroperoxide species through O2 insertion, which is the rate-determining step for H2O2 production. Meanwhile, the Ni moiety promotes H2O2 formation by activating solvents as proton sources. We also found that H2O2 production is strongly affected by the solvent dielectric constants (DE); the highest H2O2 concentration was obtained in ethylene glycol with a moderate DE. The catalytic mechanism of H2O2 production by the Ir-Ni complex was discussed, based on kinetic analysis, isotope labelling experiments, and theoretical DFT calculations.

Formate-driven catalysis and mechanism of an iridium-copper complex for selective aerobic oxidation of aromatic olefins in water.

A hetero-dinuclear IrIII-CuII complex with two adjacent sites was employed as a catalyst for the aerobic oxidation of aromatic olefins driven by formate in water. An IrIII-H intermediate, generated through formate dehydrogenation, was revealed to activate terminal aromatic olefins to afford an Ir-alkyl species, and the process was promoted by a hydrophobic [IrIII-H]-[substrate aromatic ring] interaction in water. The Ir-alkyl species subsequently reacted with dioxygen to yield corresponding methyl ketones and was promoted by the presence of the CuII moiety under acidic conditions. The IrIII-CuII complex exhibited cooperative catalysis in the selective aerobic oxidation of olefins to corresponding methyl ketones, as evidenced by no reactivities observed from the corresponding mononuclear IrIII and CuII complexes, as the individual components of the IrIII-CuII complex. The reaction mechanism afforded by the IrIII-CuII complex in the aerobic oxidation was disclosed by a combination of spectroscopic detection of reaction intermediates, kinetic analysis, and theoretical calculations.

Selective catalytic 2e--oxidation of organic substrates by an FeII complex having an N-heterocyclic carbene ligand in water.

An FeII complex, 1, having a pentadentate ligand with an NHC moiety catalyzes substrate oxidation to afford 2e--oxidized products with high selectivity by suppression of overoxidation in water. A Bell-Evance-Polanyi plot for the substrate oxidation catalyzed by 1 exhibited an inflection point around 86 kcal mol-1, indicating strong C-H abstraction ability of the reactive species derived from 1.

Cooperative Effects of Heterodinuclear IrIII-MII Complexes on Catalytic H2 Evolution from Formic Acid Dehydrogenation in Water.

Novel heterodinuclear IrIII-MII complexes (M = Co, Ni, or Cu) with two adjacent reaction sites were synthesized by using 3,5-bis(2-pyridyl)-pyrazole (Hbpp) as a structure-directing ligand and employed as catalysts for H2 evolution through formic acid dehydrogenation in water. A cooperative effect of the hetero-metal centers was observed in the H2 evolution in comparison with the corresponding mononuclear IrIII and MII complexes as the components of the IrIII-MII complexes. The H2 evolution rate for the IrIII-MII complexes was at most 350-fold higher than that of the mononuclear IrIII complex. The catalytic activity increased in the following order: IrIII-CuII complex < IrIII-CoII complex < IrIII-NiII complex . The IrIII-H intermediates of the IrIII-MII complexes were successfully detected by ultraviolet-visible, 1H nuclear magnetic resonance, and ESI-TOF-MS spectra. The catalytic enhancement of H2 evolution by the IrIII-MII complexes indicates that the IrIII-H species formed in the IrIII moiety act as reactive species and the MII moieties act as acceleration sites by the electronic effect from the MII center to the IrIII center through the bridging bpp- ligand. The IrIII-MII complexes may also activate H2O at the 3d MII centers as a proton source to facilitate H2 evolution. In addition, the affinity of formate for the IrIII-MII complexes was investigated on the basis of Michaelis-Menten plots; the IrIII-CoII and IrIII-NiII complexes exhibited affinities that were relatively higher than that of the IrIII-CuII complex. The catalytic mechanism of H2 evolution by the IrIII-MII complexes was revealed on the basis of spectroscopic detection of reaction intermediates, kinetic analysis, and isotope labeling experiments.

Mechanistic Insight into Synergistic Catalysis of Olefin Hydrogenation by a Hetero-Dinuclear RuII-CoII Complex with Adjacent Reaction Sites.

We have designed and synthesized a hetero-dinuclear RuII-CoII complex with a dinucleating ligand inspired by hetero-dinuclear active sites of metalloenzymes. A synergistic effect between the adjacent RuII and CoII sites has been confirmed in catalytic olefin hydrogenation by the complex, exhibiting a much higher turnover number than those of mononuclear RuII or CoII complexes as the components. A RuII-hydrido species was detected by 1H NMR and electrospray ionization (ESI)-time-of-flight (TOF)-MS measurements as an intermediate to react with olefins, and CoII-bound methanol was suggested to act as a proton source.

Metal-Oxyl Species and Their Possible Roles in Chemical Oxidations.

Metal-oxyl (Mn+-O•) complexes having an oxyl radical ligand, which are electronically equivalent to well-known metal-oxo (M(n+1)+═O) complexes, are surveyed as a new category of metal-based oxidants. Detection and characterization of Mn+-O• species have been made in some cases, although proposals and characterization of the species are mostly done on the basis of density functional theory (DFT) calculations. The reactivity of Mn+-O• complexes will provide a way to achieve potentially difficult oxidative conversion of substrates. This Viewpoint will provide state-of-the-art knowledge on the Mn+-O• species in terms of the formation, characterization, and DFT-based proposals to shed light on the characteristics of the intriguing oxidatively active species.

A Ruthenium(III)-Oxyl Complex Bearing Strong Radical Character.

Proton-coupled electron-transfer oxidation of a RuII -OH2 complex, having an N-heterocyclic carbene ligand, gives a RuIII -O. species, which has an electronically equivalent structure of the RuIV =O species, in an acidic aqueous solution. The RuIII -O. complex was characterized by spectroscopic methods and DFT calculations. The oxidation state of the Ru center was shown to be close to +3; the Ru-O bond showed a lower-energy Raman scattering at 732 cm-1 and the Ru-O bond length was estimated to be 1.77(1) Å. The RuIII -O. complex exhibits high reactivity in substrate oxidation under catalytic conditions; particularly, benzaldehyde and the derivatives are oxidized to the corresponding benzoic acid through C-H abstraction from the formyl group by the RuIII -O. complex bearing a strong radical character as the active species.

Abnormal killer inhibitory receptor expression on natural killer cells in patients with Behçet's disease.

Viral infection has been assigned some role in the pathogenesis of Behçet's disease (BD). Defects in natural killer (NK) cell repertoire may be involved in impaired antiviral immunity, leading to the development of BD. We studied killer inhibitory receptor (KIR) expression in 40 patients with BD. CD94 and CD158b expression of NK cells was normal in a great majority of BD patients. NKB1 expression was reduced in eight and increased in six. Twelve of these 14 patients (86%) had severe eye disease. Some had reduced NKB1 and enhanced CD158a expression simultaneously, or enhanced NKB1 and reduced CD158a simultaneously, suggesting a skewed NK cell repertoire in BD. Collectively, KIR expression was abnormal in the BD patients with severe eye disease. This may result from genetic predisposition, or certain viruses may affect the KIR repertoire formation in BD patients. Abnormal KIR expression of NK cells may be associated with the development of BD.