Biomass is an important feedstock for the renewable production of fuels, chemicals, and energy. As of 2005, over 3% of the total energy consumption in the United States was supplied by biomass, and it recently surpassed hydroelectric energy as the largest domestic source of renewable energy. Similarly, the European Union received 66.1% of its renewable energy from biomass, which thus surpassed the total combined contribution from hydropower, wind power, geothermal energy, and solar power. In addition to energy, the production of chemicals from biomass is also essential; indeed, the only renewable source of liquid transportation fuels is currently obtained from biomass.

The Catalytic Valorization of Lignin for the Production of Renewable Chemicals

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Aryl-aryl bond formation one century after the discovery of the Ullmann reaction.

Interest in catalysis by metal nanoparticles (NPs) is increasing dramatically, as reflected by the large number of publications in the last five years. This field, "semi-heterogeneous catalysis", is at the frontier between homogeneous and heterogeneous catalysis, and progress has been made in the efficiency and selectivity of reactions and recovery and recyclability of the catalytic materials. Usually NP catalysts are prepared from a metal salt, a reducing agent, and a stabilizer and are supported on an oxide, charcoal, or a zeolite. Besides the polymers and oxides that used to be employed as standard, innovative stabilizers, media, and supports have appeared, such as dendrimers, specific ligands, ionic liquids, surfactants, membranes, carbon nanotubes, and a variety of oxides. Ligand-free procedures have provided remarkable results with extremely low metal loading. The Review presents the recent developments and the use of NP catalysis in organic synthesis, for example, in hydrogenation and C--C coupling reactions, and the heterogeneous oxidation of CO on gold NPs.

Nanoparticles as Recyclable Catalysts: The Frontier between Homogeneous and Heterogeneous Catalysis

Efficient and reliable amplification of chirality has borne its greatest fruit with transition metal-catalyzed reactions since enantiocontrol may often be imposed by replacing an achiral or chiral racemic ligand with one that is chiral and scalemic While the most thoroughly developed enantioselective transition metal-catalyzed reactions are those involving transfer of oxygen (epoxidation and dihydroxylation)1,2 and molecular hydrogen,3 the focus of this review is on the area of enantioselective transition metal-catalyzed allylic alkylations which may involve C-C as well as C-X (X ) H or heteroatom) bond formation4-9 The synthetic utility of transitionmetal-catalyzed allylic alkylations has been soundly demonstrated since its introduction nearly three decades ago10-21 In contrast to processes where the allyl moiety acts as the nucleophilic partner, we will limit our discussion to processes which result in nucleophilic displacements on allylic substrates (eq 1) Such reactions have been recorded with a broad

http://web4.uwindsor.ca/users/j/jlichaa/reference.nsf/0/10ff8b04ff3a317885256d88005720f6/$FILE/cr-1996-96-395-allylpd-asym.pdf

Asymmetric Transition Metal-Catalyzed Allylic Alkylations.

Asymmetric enamine catalysis.

II.2.1. Homogeneous Systems 2166 II.2.2. Heterogeneous Systems 2168 II.3. Hydride Transfer Reduction 2169 II.3.1. Homogeneous Systems 2169 II.3.2. Heterogeneous Systems 2171 II.4. Hydrosilylation 2172 III. C−O Bond Formation 2173 III.1. Epoxidation of Unfunctionalized Olefins 2173 III.1.1. Homogeneous Catalysis 2173 III.1.2. Heterogeneous System 2176 III.2. Dihydroxylation of Olefins 2178 III.2.1. Homogeneous Systems 2178 III.2.2. Heterogeneous System 2178 III.3. Ring Opening of Meso Epoxides 2180 III.4. Kinetic Resolution 2180 III.4.1. Terminal Epoxides 2180 III.4.2. Secondary Alcohols 2181 IV. C−H Bond Oxidation 2181 IV.1. Allylic and Benzylic Oxidation 2181 IV.2. Baeyer−Villiger-type Reaction 2181 IV.3. Wacker-type Cyclization 2182 V. S−O Bond Formation 2182 VI. C−N Bond Formation 2183 VI.1. Hydroboration/Amination 2183 VI.2. Enolate Amination 2183 VI.3. Aza-Claisen Rearrangement 2183 VI.4. Azide Synthesis 2184 VI.5. Aminohydroxylation 2184 VI.6. Aziridine Synthesis 2184 VI.7. C−N Bond Formation via S−N Bond Formation 2185

Nitrogen-containing ligands for asymmetric homogeneous and heterogeneous catalysis.

Stereoselective reduction of disubstituted aromatics on colloidal rhodium

An alternative catalytic method to the Williamson's synthesis of ethers

The nature of the Rh−diamine precursor in the catalytic cycle of the asymmetric hydride transfer reduction of carbonyl compounds was examined by both theoretical and experimental approaches. On the one hand, calculations based on the DFT theory were performed on various [RhH(NH3)n(C2H4)4-n] complexes, in the trigonal bipyramidal (TBP) and square pyramidal (SP) forms. Their geometry has been fully optimized, and it was found that the only stable complex corresponds to n = 2 in a TBP form, with the ethylenes in the equatorial plane. On the other hand, mass analyses of the synthesized complexes showed that their composition was [Rh(COD)(diamine)]+ X- (X- = Cl- or PF6-). Several experiments were performed to study the influence of the ligand stoichiometry, the nature of the diene (cyclooctadiene (COD) or others). Finally, the two methods converged and proved that the active species contains only one diamine and one diene bound to the metal.

Fabienne Fache

Papers

Nitrogen-containing ligands for asymmetric homogeneous and heterogeneous catalysis.

Stereoselective reduction of disubstituted aromatics on colloidal rhodium

An alternative catalytic method to the Williamson's synthesis of ethers

Structure of the Diamine−Rh(I) Precursor in the Asymmetric Hydride Transfer Reduction of Ketones: A Theoretical and Experimental Approach

A catalytic stereo- and chemo-selective method for the reduction of substituted aromatics