Synthesis of cyclic sulfites from epoxides and sulfur dioxide with silica-immobilized homogeneous catalysts.

Quaternary ammonium- and amino-functionalized silica catalysts have been prepared for the selective synthesis of cyclic sulfites from epoxides and sulfur dioxide, demonstrating the effects of immobilizing the homogeneous catalysts on silica. The cycloaddition of sulfur dioxide to various epoxides was conducted under solvent-free conditions at 100 °C. The quaternary ammonium- and amino-functionalized silica catalysts produced cyclic sulfites in high yields (79-96 %) that are comparable to those produced by the homogeneous catalysts.

The synthesis of organic carbonates from carbon dioxide.

Carbon dioxide (CO(2)) is an easily available, renewable carbon resource, which has the advantages of being non-toxic, abundant and economical. CO(2) is also attractive as an environmentally friendly chemical reagent, and is especially useful as a phosgene substitute. CO(2) is an "anhydrous carbonic acid" that rapidly reacts with basic compounds.

Fe(OTf)(3)-catalyzed addition of sp C-H bonds to olefins.

We have developed a novel acid-catalyzed addition of acetylenes to olefins in the presence of catalytic triflic acid or its metal salts. Among the various triflates, the catalytic activities depend on the cation and decrease in the order Fe(3+) > Al(3+) >> H(+), In(3+), Sc(3+) >> Cu(2+), Ag(+). In general, "hard" acids gave higher yields than "soft" acids such as copper and silver triflates.

Iron-catalysed green synthesis of carboxylic esters by the intermolecular addition of carboxylic acids to alkenes.

Iron triflate, in situ-formed from FeCl3 and triflic acid, or FeCl3 and silver triflate efficiently catalyse the intermolecular addition of carboxylic acids to various alkenes to yield carboxylic esters; the reaction is applicable to the synthesis of unstable esters, such as acrylates.

Remarkable acceleration of cyanosilylation by the mesoporous Al-MCM-41 catalyst.

The presence of the heterogeneous mesoporous Al-MCM-41 catalyst remarkably accelerated the cyanosilylation of various aldehydes and ketones with trialkylsilyl cyanide, giving the corresponding cyanohydrin silyl ethers in quantitative yields under mild reaction conditions.

Synergistic hybrid catalyst for cyclic carbonate synthesis: remarkable acceleration caused by immobilization of homogeneous catalyst on silica.

The catalytic activity of phosphonium salts towards cyclic carbonate synthesis from propylene oxide and CO2 has been enormously enhanced by their immobilization onto silica that itself has no catalytic activity.

Microwave-assisted direct transformation of amines to ketones using water as an oxygen source.

Retro-reductive aminations, direct transformations of amines to ketones, were catalyzed by Pd/C in water under microwave irradiation.

Oxidative addition of C-H bonds to RhCl(PMe3)3: relevant to the catalytic transformation of hydrocarbons.

RhCl(PMe3)3 (1) reacts with benzene under irradiation to give the oxidative addition product, Rh(C6H5)(H)Cl(PMe3)3 (2). The reaction is promoted under CO2 atmosphere. The structure of 2 was fully characterized by X-ray crystallography as well as NMR, IR, and elemental analysis.