Yoshinori Yamamoto

Bio: Yoshinori Yamamoto is an academic researcher from Dalian University of Technology. The author has contributed to research in topics: Palladium & Catalysis. The author has an hindex of 85, co-authored 950 publications receiving 28130 citations. Previous affiliations of Yoshinori Yamamoto include Kyoto University & King Abdulaziz University.

Coinage Metal-Assisted Synthesis of Heterocycles

Abstract: 2.4. Tandem sp-sp Coupling/Cyclization 3418 3. Cycloaddition Reactions 3418 3.1. [3+2] Cycloaddition 3418 3.1.1. Triazole/Isoxazole-Forming Reactions 3418 3.1.2. Reactions of Azomethine Ylides 3419 3.1.3. Cycloaddition of Nitrones 3422 3.1.4. Other [3+2] Reaction 3422 3.2. [4+2] Heterocycloaddition 3422 3.3. [2+2] Cycloaddition 3424 4. Cycloisomerization of Enynes/Diynes 3425 5. Intramolecular Friedel-Crafts-Type Reactions 3428 6. Reactions of R-Diazocarbonyl Compounds 3429 7. Aziridination of Olefins 3431 8. N/O-Vinylation/Arylation 3431 9. Radical Cyclization of Haloalkenes and Haloalkynes 3433

Atomic origins of the high catalytic activity of nanoporous gold

Abstract: Distinct from inert bulk gold, nanoparticulate gold has been found to possess remarkable catalytic activity towards oxidation reactions. The catalytic performance of nanoparticulate gold strongly depends on size and support, and catalytic activity usually cannot be observed at characteristic sizes larger than 5 nm. Interestingly, significant catalytic activity can be retained in dealloyed nanoporous gold (NPG) even when its feature lengths are larger than 30 nm. Here we report atomic insights of the NPG catalysis, characterized by spherical-aberration-corrected transmission electron microscopy (TEM) and environmental TEM. A high density of atomic steps and kinks is observed on the curved surfaces of NPG, comparable to 3-5 nm nanoparticles, which are stabilized by hyperboloid-like gold ligaments. In situ TEM observations provide compelling evidence that the surface defects are active sites for the catalytic oxidation of CO and residual Ag stabilizes the atomic steps by suppressing {111} faceting kinetics.

From σ- to π-Electrophilic Lewis Acids. Application to Selective Organic Transformations

Abstract: Computed enthalpies of formation for various Lewis acid complexes with representative unsaturated compounds (aldehydes, imines, alkynes, and alkenes) provide a means to evaluate the applicability of a particular catalyst in a catalytic reaction. As expected, main group Lewis acids such as BX3 show much stronger complexes with heteroatoms than with carbon−carbon multiple bonds (σ-electrophilic Lewis acids). Gold(I) and copper(I) salts with non-nucleophilic anions increase the relative strength of coordination to the carbon−carbon multiple bonds (π-electrophilic Lewis acids). As representative examples for the use of σ-electrophilic Lewis acids in organic synthesis, the Lewis acid mediated allylation reactions of aldehydes and imines with allylic organometallic reagents which give the corresponding homoallyl alcohols and amines, respectively, are mentioned. The allylation method is applied for the synthesis of polycyclic ether marine natural products, such as hemibrevetoxin B, gambierol, and brevetoxin B. A...

Lewis acid-catalyzed benzannulation via unprecedented [4+2] cycloaddition of o-alkynyl(oxo)benzenes and enynals with alkynes.

Abstract: The reaction of o-alkynyl(oxo)benzenes 1 with alkynes 2 in the presence of a catalytic amount of AuCl3 in (CH2Cl)2 at 80 °C gave the [4+2] benzannulation products, naphthyl ketone derivatives 3 and 4, in high yields. When the reaction was carried out using AuBr3 instead of AuCl3, the reaction speed was enhanced and the chemical yield was increased. On the other hand, when the reaction was carried out in the presence of a catalytic amount of Cu(OTf)2 and 1 equiv of a Bronsted acid, such as CF2HCO2H, in (CH2Cl)2 at 100 °C, the decarbonylated naphthalene products 5 were obtained in high yields. Similarly, the Cu(OTf)2−H2O-promoted reaction of the enynals 7 with an alkyne 2 afforded the corresponding [4+2] benzannulation products, decarbonylated benzene derivatives 8, in good yields. Both AuX3- and Cu(OTf)2-catalyzed benzannulations proceed most probably through the formation of the benzo[c]pyrylium ate complex 10, the Diels−Alder addition of alkynes 2 to the ate complex, and the resulting bicyclic pyrylium i...

Cu-catalyzed azide-alkyne cycloaddition.

Abstract: The Huisgen 1,3-dipolar cycloaddition reaction of organic azides and alkynes has gained considerable attention in recent years due to the introduction in 2001 of Cu(1) catalysis by Tornoe and Meldal, leading to a major improvement in both rate and regioselectivity of the reaction, as realized independently by the Meldal and the Sharpless laboratories. The great success of the Cu(1) catalyzed reaction is rooted in the fact that it is a virtually quantitative, very robust, insensitive, general, and orthogonal ligation reaction, suitable for even biomolecular ligation and in vivo tagging or as a polymerization reaction for synthesis of long linear polymers. The triazole formed is essentially chemically inert to reactive conditions, e.g. oxidation, reduction, and hydrolysis, and has an intermediate polarity with a dipolar moment of ∼5 D. The basis for the unique properties and rate enhancement for triazole formation under Cu(1) catalysis should be found in the high ∆G of the reaction in combination with the low character of polarity of the dipole of the noncatalyzed thermal reaction, which leads to a considerable activation barrier. In order to understand the reaction in detail, it therefore seems important to spend a moment to consider the structural and mechanistic aspects of the catalysis. The reaction is quite insensitive to reaction conditions as long as Cu(1) is present and may be performed in an aqueous or organic environment both in solution and on solid support.

Organic Photoredox Catalysis

Abstract: In this review, we highlight the use of organic photoredox catalysts in a myriad of synthetic transformations with a range of applications. This overview is arranged by catalyst class where the photophysics and electrochemical characteristics of each is discussed to underscore the differences and advantages to each type of single electron redox agent. We highlight both net reductive and oxidative as well as redox neutral transformations that can be accomplished using purely organic photoredox-active catalysts. An overview of the basic photophysics and electron transfer theory is presented in order to provide a comprehensive guide for employing this class of catalysts in photoredox manifolds.

Gold-Catalyzed Organic Reactions

Abstract: Although homogeneous gold catalysis was known previously, an exponential growth was only induced 12 years ago. The key findings which induce that rise of the field are discussed. This includes early reactions of allenes and furanynes and intermediates of these conversions as well as hydroarylation reactions. Other substrate types addressed are alkynyl epoxides and N-propargyl carboxamides. Important vinylgold intermediates, the transmetalation from gold to other transition metals, the development of new ligands for gold catalysis, and significant contributions from computational chemistry are other crucial points for the field highlighted here.