Ken Motokura

Treatment of a hydrotacite, Mg6Al2(OH)16CO3, with an aqueous solution of RuCl3.nH2O afforded a monomeric Ru(IV) species on the surface of the hydrotalcite. This novel Ru-grafted hydrotalcite (Ru/HT) efficiently catalyzed alpha-alkylation of nitriles with primary alcohols through the cooperative catalysis between the Ru species and the surface base sites. The catalyst system could be further extended for the one-pot synthesis of alpha,alpha-dialkylated phenylacetonitriles via the base-catalyzed M

We have developed an environmentally benign synthetic approach to nucleophilic substitution reactions of alcohols that minimizes or eliminates the formation of byproducts, resulting in a highly atom-efficient chemical process. Proton- and metal-exchanged montmorillonites (H- and Mn+-mont) were prepared easily by treating Na+-mont with an aqueous solution of hydrogen chloride or metal salt, respectively. The H-mont possessed outstanding catalytic activity for nucleophilic substitution reactions o

A Ti4+-exchanged montmorillonite (Ti4+-mont) and a hydrotalcite (HT) are strong solid Brønsted acid and base, and these two clay catalysts could be used in a single reactor without neutralization of active sites. Because the Ti4+-mont have active acid site in the narrow interlayers, the base sites of large HT particles show no interaction with the acid sites. A variety of acid and base reactions, such as esterification, acetalization, deacetalization, aldol reaction, Michael reaction, and epoxid

A copper-catalyzed formic acid synthesis from CO2 with hydrosilanes has been accomplished. The Cu(OAc)2·H2O-1,2-bis(diphenylphosphino)benzene system is highly effective for the formic acid synthesis under 1 atm of CO2. The TON value approached 8100 in 6 h. The reaction pathway was revealed by in situ NMR analysis and isotopic experiments.

Silica-supported 4-pyrrolidinopyridinium iodide was prepared by quaternization of 4-pyrrolidinopyridine with silica-supported alkyl iodide. The pyrrolidinopyridinium structure on the silica surface was confirmed by solid-state 13C CP MAS NMR. The silica-supported 4-pyrrolidinopyridinium iodide showed excellent catalytic performances for transformations of various epoxides to cyclic carbonates under atmospheric pressure of carbon dioxide (CO2). The reactions took place without any solvents or add

Amorphous silica-alumina-supported amines (SA-NR2) were found to be excellent heterogeneous catalysts for a variety of carbon−carbon bond-forming reactions, such as cyano-O-ethoxycarbonylation, Michael reaction, and nitro-aldol reaction. These reactions were hard to proceed either with amines alone or on the SA alone. Solid-state 13C MAS NMR analysis revealed the acid−base interaction of the H+ site and amine group on the SA-NR2 surface, which makes an acid−base dual activation mechanism possibl

The unique acidity of a proton-exchanged montmorillonite catalyst (H-mont) was exploited in the nucleophilic addition of 1,3-dicarbonyl compounds to simple alkenes (see scheme). The benzylation and allylation of 1,3-dicarbonyl compounds with alcohols and nucleophilic addition of carboxylic acids to alkenes also proceeded smoothly with the H-mont catalyst, which could be recovered easily and recycled at least seven times without loss of activity. Supporting information for this article is availab

A ruthenium-grafted hydrotalcite (Ru/HT) and hydrotalcite-supported palladium nanoparticles (Pd(nano)/HT) are easily prepared by treating basic layered double hydroxide, hydrotalcite (HT, Mg(6)Al(2)(OH)(16)CO(3)) with aqueous RuCl(3)n H(2)O and K(2)[PdCl(4)] solutions, respectively, using surface impregnation methods. Analysis by means of X-ray diffraction, and energy-dispersive X-ray, electron paramagnetic resonance, and X-ray absorption fine structure spectroscopies proves that a monomeric Ru(

Acidic montmorillonite-immobilized primary amines (H-mont-NH(2)) were found to be excellent acid-base bifunctional catalysts for one-pot reaction sequences, which are the first materials with coexisting acid and base sites active for acid-base tamdem reactions. For example, tandem deacetalization-Knoevenagel condensation proceeded successfully with the H-mont-NH(2), affording the corresponding condensation product in a quantitative yield. The acidity of the H-mont-NH(2) was strongly influenced b

Nucleophilic addition of sulfonamides and carboxamides to simple alkenes proceeded smoothly using a proton-exchanged montmorillonite catalyst. The spent catalyst was recovered easily from the reaction mixture and was reusable at least five times without any loss of activity. The unique acidity of the proton-exchanged montmorillonite (H-mont) catalyst was found to be applicable to additional reactions: substitution of hydroxyl groups of alcohols with amides and anilines.

D'you know what amine? Primary and tertiary amines are both immobilized on the same silica–alumina surface by silane-coupling reactions. The resultant silica–alumina-supported double-amines are found to exhibit excellent catalysis for 1,3-dinitroalkane synthesis from various aldehydes with nitromethane. A cooperative catalytic mechanism on the solid surface for this efficient synthesis is proposed. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such

Silica-supported metal complex catalysts have been developed and used for organic transformations. The surface environment around the supported metal complex enhances the catalysis based on a unique surface effect. The design of the linker ligand structure induces the formation of a highly reactive, coordinatively unsaturated metal complex on the silica surface because of the isolated environment. In contrast to the site-isolation effect, the accumulated metal complexes and cocatalysts on the sa

Abstract Acid–base bifunctional heterogeneous catalysts were prepared by the reaction of an acidic silica–alumina (SA) surface with silane‐coupling reagents possessing amino functional groups. The obtained SA‐supported amines (SA–NR 2 ) were characterized by solid‐state 13 C and 29 Si NMR spectroscopy, FT‐IR spectroscopy, and elemental analysis. The solid‐state NMR spectra revealed that the amines were immobilized by acid–base interactions at the SA surface. The interactions between the surface

Various organocatalysts are developed to accelerate the carbon dioxide utilisation as feedstock to value-added organic chemicals synthesis with silanes as strategic reducing agents.