Photolysis of organopolysilanes. Reactions of trimethylsilylphenylsilylene with carbonyl compounds

Photolysis of tris(trimethylsilyl)phenylsilane (I) in the presence of acetone, diethyl ketone and cyclohexanone resulted in formation of the respective 2,2,2-trimethylphenyldisilanyl enol ethers in moderate yields. UV-irradiation of I in the presence of methyl acrylate, followed by treatment of the reaction mixture with isopropyl alcohol, afforded methyl 3-(1′-isopropoxy-1′-phenyltrimethyldisilanyl)propionate, in addition to an adduct arising from addition of a silicon-carbon double-bonded intermediate to the carbon-carbon double bond.     

Lipase-catalyzed interesterification of soybean oil with an omega-3 polyunsaturated fatty acid concentrate prepared from sardine oil

To reduce the content of linoleoyl moiety in soybean oil, soybean oil that contains 53.0% linoleoyl moiety as molar acyl moiety composition was interesterified with an omega-3 polyunsaturated fatty acid (PUFA) concentrate (24.0 mol% eicosapentaenoic acid [EPA], 40.4 mol% docosahexaenoic acid [DHA]) prepared from sardine oil, using an immobilized sn-1,3-specific lipase from Rhizomucor miehei (Lipozyme IM). The reaction was carried out in a batch reactor at 37 degrees C under the following conditions: 500 micromol of soybean oil, molar ratio of omega-3 PUFA concentrate to soybean oil = 1.0-6.0,5.0 mL of heptane, and 30 batch interesterification units of enzyme. After the reaction time of 72 h, modified soybean oil, which contains 34.9% linoleoyl, 10.1% eicosapentaenoyl, and 14.2% docosahexaenoyl moieties, was produced at the molar reactant ratio of 6.0. In this oil, the total omega-3 acyl moiety composition reached 34.1%; the molar ratio of omega-3 to omega-6 acyl moieties was enhanced by five times compared with soybean oil. Compared with palmitic acid, DHA was kinetically six times less reactive, although the EPA was by 16% more reactive.     

A circular tris[2]catenane from molecular 'figure-of-eight'

A 'figure-of-eight'-shaped molecule with Pd(ii) at the node was self-assembled into an unprecedented circular tris[2]catenane via reversible double catenation at both loops of the 'figure-of-eight' molecule.     

Hemilabile amidomonophosphine ligand-rhodium(I) complex-catalyzed asymmetric 1,4-addition of arylboronic acids to cycloalkenones

The asymmetric 1,4-addition reaction of arylboronic acids with cycloalkenones was catalyzed by 1 mol % of an amidomonophosphine-rhodium(I) catalyst in a 10:1 mixture of 1,4-dioxane and water at 100 degrees C, affording 3-arylcycloalkanones in reasonably high enantioselectivity and high yields. It was revealed by NMR, IR, and X-ray spectroscopies that this bidentate amidomonophosphine behaves as a hemilabile ligand that contains a hard donor site in addition to the soft donor in a molecule. Phosphorus atom strongly bonds to rhodium(I), and the amide carbonyl oxygen is coordinatively labile. The reaction efficacy of phenylboronic acid with cyclopent-2-en-1-one was significantly dependent on the possibility of coordination of the amide carbonyl oxygen to rhodium(I).     

Two new meroterpenoids, penisimplicin A and B, isolated from Penicillium simplicissimum

In the course of our research for new antifungal agents, two new meroterpenoids, penisimplicin A (1) and B (2), were isolated from Penicillium simplicissimum. The absolute structures of 1 and 2 were established by spectroscopic and chemical investigation. Penisimplicin A (1) and B (2) are rare examples of D-ring seco-meroterpenoids. Since compounds 1 and 2 showed no antifungal activities, the isolation of the compounds with antifungal activity will be attempted.     

X-ray structural studies ofβ-cyclodextrin inclusion complexes with racemic andS(−) methyl-p-tolylsulfoxides

In order to clarify the reason why the stereospecific sulfoxides undergo racemization in solution but not in the complex crystal with -cyclodextrin (-CD) in the solid state, a crystal structure analysis of two -CD inclusion complexes with methyl-p-tolylsulfoxide (MTSO) having a chiral sulfur atom was carried out.     

Experimental and theoretical studies on the organic-inorganic hybrid compound: aluminum-NTCDA Co-deposited film

Electronic absorption, Fourier transform-infrared (FT-IR), and electron spin resonance spectra of aluminum-naphthalene tetracarboxylic dianhydlide (Al-NTCDA) co-deposited film have been measured at room temperature, and hybrid density functional theory (DFT) calculations have been carried out in order to elucidate the electronic states for the ground and low-lying excited states of the complexes. After the interaction of NTCDA with Al atom, the new electronic transition bands were appeared at near-IR region. The C=O stretching modes of NTCDA are red-shifted by the interaction with Al. From the DFT calculations, it was found that the electronic state of the complex at the ground state is characterized by a slight charge-transfer state expressed by (Al(4))(delta+)(NTCDA)(delta-). The binding of Al to NTCDA is strong. The C=O double-bond character of NTCDA is changed to C-O single-bond-like character by the strong interaction of Al to the C=O bond. This is the origin of the red-shift of the FT-IR spectrum. The electronic states of organic-inorganic hybrid material were discussed on the basis of theoretical results.     

Effect of drying on the mesoporous structure of sol-gel derived silica with PPO-PEO-PPO template block copolymer

The effects of drying method on the pore structure of mesoporous silica were studied from the viewpoint of enhancing closed porosity in mesoporous silica. The mesoporous silica was prepared via a sol-gel process using polyethyleneoxide-polypropyleneoxide-polyethyleneoxide (PEO-PPO-PEO) triblock copolymer (Pluronic P123) as the structure-directing template. The closed porosity was evaluated from the apparent mass density of the sample measured by a helium pycnometer. These mesoporous silicas were also characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and nitrogen adsorption. The drying method was shown to be responsible for the finally templated mesoporous structure of the silica. More rapid drying is more preferable for enhancing the closed porosity of the mesoporous silica. The closed pores were formed by immediate immobilization of copolymer molecular assemblies in the silica matrix due to the instant removal of the solvent and solidification at higher temperatures. The drying method, mainly affecting the drying rate, is highly influential on the finally replicated mesoporous structure in silica.     

Total synthesis of (+)-tubelactomicin A. 1. Stereoselective synthesis of the lower-half segment by an intramolecular Diels-Alder approach

[reaction: see text]. Starting from diethyl (R)-malate, synthesis of the lower-half segment of (+)-tubelactomicin A, a 16-membered macrolide antibiotic, has been achieved. The synthesis involved the highly endo- and pi-facial selective intramolecular Diels-Alder reaction achieved using a trisubstituted methacrolein derivative tethering a 10-carbon dienyne unit at the beta-carbon, which in turn was prepared from a known allylated malic acid derivative.     

Effect of interfacial tension on the dynamic behavior of droplet formation during microchannel emulsification

Microchannel (MC) emulsification is a novel technique for producing monodisperse emulsions. In this study, we investigated the effect of interfacial tension on the dynamic behavior of droplet formation with various surfactant concentrations. Interfacial tension did not affect the resultant droplet diameter in lower flow velocity ranges, but it did affect the time-scale parameters. These results were interpreted using the droplet formation mechanism reported in our previous study. At surfactant concentrations below 0.3%, the emulsification behavior was differed from that at higher surfactant concentrations. An analysis of diffusional transfer indicated that dynamic interfacial tension affects the emulsification behavior at lower surfactant concentrations. Dynamic interfacial tension that exceeded the equilibrium value led to a shorter detachment time. This resulted in stable droplet formation of monodispersed emulsions by spontaneous transformation, even at flow velocities above the predicted critical flow velocity. A previous study predicted that the droplet formation would become unstable and polydispersed larger droplets would form over critical flow velocity. Wetting of the MC with the dispersed phase at lower surfactant concentrations induced formation of larger polydispersed droplets at high flow velocities.