ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPalladium-Catalyzed Asymmetric Hydrosilylation of 4-Substituted 1-Buten-3-ynes. Catalytic Synthesis Axially Chiral AllenylsilanesJin Wook Han, Norihito Tokunaga, and Tamio HayashiView Author Information Department Chemistry, Graduate School Science Kyoto University, Sakyo, 606-8502, Japan Cite this: J. Am. Chem. Soc. 2001, 123, 51, 12915–12916Publication Date (Web):November 30, 2001Publication History Received22 September 2001Revised15...

Double hydrosilylation of arylacetylenes with trichlorosilane catalyzed first by platinum and second a chiral monophosphine-palladium complex generated the corresponding 1,2-bis(silyl)-1-arylethanes, oxidation which hydrogen peroxide gave 1-aryl-1,2-diols high enantiomeric purity (94-98% ee) in yields.

A tris(7-propyl-8-hydroxyquinolinato) aluminum [Al(7-Prq)3] film shows negative giant surface potential (GSP) because of spontaneous orientation polarization. The polarity this is opposite to those tris-(8-hydroxyquinolate) films. In Al(7-Prq)3-based organic light-emitting diodes, GSP leads the positive interface charge and governs electron injection accumulation properties. addition, a high resistance at Al(7-Prq)3/Ca suggested possibly polarization interface. These results show importance...

A macroporous polymeric acid catalyst was prepared for the direct esterification of carboxylic acids and alcohols that proceeded at 50-80 °C without removal water to give corresponding esters with high yield. Flow synthesis biodiesel fuel also achieved by using a column-packed under mild conditions water.

In the context of energy crisis and global climate deterioration, sustainable development clean will become a new direction for future development. Based on process in China past ten years, this paper expounds China’s policy plan. The hydropower, wind power, solar power recent years is analyzed. On basis, Grey Forecasting Model used to forecast structure next 10 point out market opportunities future, put forward implementation methods energy. It provides reference decision-making

The addition of aryltitanium triisopropoxide (ArTi(OPr-i )3) to alpha,beta-unsaturated ketones proceeded with high enantioselectivity (94-99.8% ee) in the presence 3 mol % [Rh(OH)((S )-binap)]2 THF at 20 degrees C give yields titanium enolates as 1,4-addition products. were converted into silyl enol ethers by treatment chlorotrimethylsilane and lithium isopropoxide.

Several MOP ligands 5 containing aryl groups at 2′ position of (R)-2-(diphenylphosphino)-1,1′-binaphthyl skeleton were prepared and used for palladium-catalyzed asymmetric hydrosilylation cyclic 1,3-dienes 6 with trichlorosilane. Highest enantioselectivity was observed in the reaction 1,3-cyclopentadiene (6a) catalyzed by a palladium complex (0.25 mol %) coordinated (R)-2-(diphenylphosphino)-2′-(3,5-dimethyl-4-methoxyphenyl)-1,1′-binaphthyl (5f), which gave (S)-3-(trichlorosilyl)cyclopentene 90% ee.

Carrageenan is a commercially important polysaccharide widely applied in the food industry. Specific probes are critical tools for situ investigation of polysaccharides, whereas carrageenan-specific limited at present. Carbohydrate-binding modules (CBMs) could serve as specific polysaccharides. In present study, an unknown function module from κ-carrageenase Cgk16A was cloned and expressed Escherichia coli. The protein Cgk16A-CBM92 specifically bind to carrageenan. Its novelty sheds light on...

We examined the surface structure, binding conditions, electrochemical behavior, and thermal stability of self-assembled monolayers (SAMs) on Au(111) formed by N-(2-mercaptoethyl)heptanamide (MEHA) containing an amide group in inner alkyl chain using scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) to understand effects internal as a function deposition time. The STM study clearly showed that structural transitions MEHA SAMs occurred from...

An ansa-zirconocene compound, [2,2'-methylenebis(1,3-dimethylcyclopentadienyl)]zirconium dichloride (5), bearing methyl substituents on the carbons adjacent to a bridgehead carbon, was synthesized by key steps of catalytic Pauson−Khand reaction and retro-Diels−Alder reaction. The crystal structure 5 determined. small angle (117.15°) between two centroids cyclopentadienyls zirconium atom absence any positions β with respect carbon indicate that coordination site for catalysis is widely...

Abstract A porous p henolsulphonic a cid— f ormaldehyde r esin (PAFR) was developed. The heterogeneous catalyst PAFR applied to the esterification of carboxylic acids and alcohols, affording acid esters in yield up 95% where water not removed from reaction mixture. Surprisingly, as solvent proceeded afford desired high yield. provided corresponding higher than other homogeneous catalysts. transesterification alcohols also investigated by using PAFR, giving esters. batch-wise continuous-flow...

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTChiral Auxiliary-Directed Asymmetric Ortho-Lithiation of (Arene)tricarbonylchromium ComplexesJin Wook Han, Seung Uk Son, and Young Keun ChungView Author Information Department Chemistry Center for Molecular Catalysis, College Natural Sciences, Seoul National University, 151-742, Korea Cite this: J. Org. Chem. 1997, 62, 23, 8264–8267Publication Date (Web):November 14, 1997Publication History Received14 July 1997Published online14 November inissue 1...

The reaction of organotitanium reagents, methyltitanium triisopropoxide [MeTi(i-PrO)3] and phenyltitanium [PhTi(i-PrO)3], with aryl triflates halides proceeded in the presence 1.0 mol% palladium catalyst coordinated (R*)-N,N-dimethyl-1-[(S*)-2-(diphenylphosphino)ferrocenyl]ethyl­amine [(R*)-(S*)-PPFA] refluxing THF to give a quantitative yield corresponding cross-coupling products.

In this contribution, we report the synthesis of organic–inorganic macrocyclic molecular brushes with a 24-membered oligomeric silsesquioxane (MOSS) backbone and poly(ε-caprolactone) (PCL) (or poly(ε-caprolactone)-block-polystyrene (PCL-b-PS) diblock copolymer) side chains. The were incorporated into epoxy to access nanostructured thermosets. nanostructures in thermosets investigated by means atomic force microscopy (AFM), small angle X-ray scattering (SAXS) dynamic mechanical thermal...

Gold-catalyzed aerobic oxygenative cleavage of triple bonds that occurs under the ambient pressure air and at room temperature is reported; radical inhibition tests suggest oxygenation via a gold-bound metalloradical intermediate.

Bis{(Rp)-2-[(1S)-1-methoxyethyl]ferrocenyl}arylphosphines (S,Rp)-9 (aryl=4-MeOC6H4 (9a), Ph (9b), 4-CF3C6H4 (9c), 3,5-(CF3)2C6H3 (9d)), which contain two planar chiral ferrocenyl moieties, were prepared via (Rp)-1-bromo-2-[(1S)-1-methoxyethyl]ferrocene ((S,Rp)-8). Asymmetric hydrosilylation of linear 1,3-dienes such as deca-1,3-diene (10a) with trichlorosilane in the presence a palladium catalyst coordinated 9d gave allylic silanes up to 93% ee.

Isochromenylium-4-ylplatinum(II) species, generated from 1-(2-alkynylphenyl)hex-5-en-1-ones and Pt(II), reacted with a pendant olefin via [3+2] cycloaddition to form tetracyclic Pt-carbene complexes, which underwent C-H insertion benzyloxy group at δ or ε positions give highly complex polycycles, are otherwise hard access.

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication the EditorNEXTHighly Porous Polysilsesquioxane Networks via Hydrosilylative Polymerization of Macrocyclic Oligomeric SilsesquioxanesJin Han and Sixun Zheng*View Author Information Department Polymer Science Engineering, Shanghai Jiao Tong University, 200240, P. R. China* To whom correspondence should be addressed: Tel 86-21-54743278 ; Fax 86-21-54741297; e-mail [email protected]Cite this: Macromolecules 2008, 41, 13,...