Novel imidazolium ion-tagged Ru-carbene complexes: synthesis and applications for olefin metathesis in ionic liquid

Novel Hoveyda-type Ru-carbene complexes 7a,b and 8a,b tethering imidazolium tags at chelating isopropoxy group have been synthesized, and investigated their catalytic activities and recyclabilities in ring-closing metathesis (RCM) and cross metathesis (CM) in ionic liquids. They showed excellent catalytic activities for RCM of various dienes in [bmim][PF₆]/CH₂Cl₂ (1/1, v/v). The recyclability of these catalysts is largely dependent on the tether length and the structures of imidazolium tag and ionic liquid, as well as the composition of the ionic solvent system. A combination of the 2-methylated imidazolium ion-tagged Ru-complex 7b with a mixture of [bdmim][PF₆]/toluene (1/3, v/v) allowed several times recycling without significant loss of catalytic activity in RCM, however low recyclabilities were observed in CMs.     

Highly selective ammonia synthesis from nitrate with photocatalytically generated hydrogen on CuPd/TiO2

Body-centered-cubic type CuPd nanoalloys were synthesized by a chemical reduction method. Photocatalytic hydrogen evolution and nitrate reduction were simultaneously examined over CuPd nanoalloys deposited on TiO(2) (CuPd/TiO(2)). The efficiency of hydrogen evolution over CuPd/TiO(2) was better than that over Pd/TiO(2). As for nitrate reduction, ammonia was selectively (78%) produced with hydrogen generated photocatalytically over CuPd/TiO(2). The continuous generation of nascent hydrogen atoms on the surface of the CuPd nanoalloy, where Cu and Pd are homogeneously mixed, led to the high selectivity for ammonia.     

Ginkgo biloba extract (GbE) enhances the anti-atherogenic effect of cilostazol by inhibiting ROS generation

In this study, the synergistic effect of 6-[4-(1-cyclohexyl- 1H-tetrazol-5-yl) butoxy]-3,4-dihydro-2(1H )-quinolinone (cilostazol) and Ginkgo biloba extract (GbE) was examined in apolipoprotein E (ApoE) null mice. Co-treatment with GbE and cilostazol synergistically decreased reactive oxygen species (ROS) production in ApoE null mice fed a high-fat diet. Co-treatment resulted in a significantly decreased atherosclerotic lesion area compared to untreated ApoE mice. The inflammatory cytokines and adhesion molecules such as monocyte chemoattractant-1 (MCP-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), and VCAM-1 which can initiate atherosclerosis were significantly reduced by the co-treatment of cilostazol with GbE. Further, the infiltration of macrophages into the intima was decreased by co-treatment. These results suggest that co-treatment of GbE with cilostazol has a more potent anti-atherosclerotic effect than treatment with cilostazol alone in hyperlipidemic ApoE null mice and could be a valuable therapeutic strategy for the treatment of atherosclerosis.     

Control of peptide assembly through directional interactions

We demonstrate the self-assembly of tripeptide amphiphiles into spherical hollow capsules from linear nanoribbons via control of the molecular packing. We achieved a transition of arrangement from anisotropic to isotropic by an elaborate design of the molecular architecture.     

Pd/light-accelerated atom-transfer carbonylation of alkyl iodides: applications in multicomponent coupling processes leading to functionalized carboxylic acid derivatives

The atom-transfer carbonylation reaction of various alkyl iodides thereby leading to carboxylic acid esters was effectively accelerated by the addition of transition-metal catalysts under photoirradiation conditions. By using a combined Pd/hν reaction system, vicinal C-functionalization of alkenes was attained in which α-substituted iodoalkanes, alkenes, carbon monoxide, and alcohols were coupled to give functionalized esters. When alkenyl alcohols were used as acceptor alkenes, three-component coupling reactions, which were accompanied by intramolecular esterification, proceeded to give lactones. Pd-dimer complex [Pd(2)(CNMe)(6)][PF(6)](2), which is known to undergo homolysis under photoirradiation conditions, worked quite well as a catalyst in these three- or four-component coupling reactions. In this metal/radical hybrid system, both Pd radicals and acyl radicals are key players and a stereochemical study confirmed the carbonylation step proceeded through a radical carbonylation mechanism.