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Heterogenized photoredox catalysts provide a path for sustainable chemical synthesis using highly tunable, reusable constructs. Here, heterogenized iridium complexes as photoredox catalysts were assembled via covalent attachment to metal oxide surfaces (ITO, ZrO2, Al2O3) in thin film or nanopowder constructs. The goal was to understand which materials provided the most promising constructs for catalysis. To do this, reductive dehalogenation of bromoacetophenone to acetophenone was studied as a test reaction for system optimization. All catalyst constructs produced acetophenone with high conversions and yields with the fastest reactions complete in fifteen minutes using Al2O3 supports. The nanopowder catalysts resulted in faster and more efficient catalysis, while the thin film catalysts were more robust and easily reused. Importantly, the thin film constructs show promise for future photoelectrochemical and electrochemical photoredox setups. Finally, all catalysts were reusable 2–3 times, performing at least 1000 turnovers (Al2O3), demonstrating that heterogenized catalysts are a sustainable catalyst alternative. [ABSTRACT FROM AUTHOR]

Abstract: Nanoparticles, being objects with high surface area are prone to agglomeration. Immobilization onto solid supports is a promising method to increase their stability and it allows for scalable industrial applications, such as metal nanoparticles adsorbed to mesoporous ceramic carriers. Tubular nanoclay – halloysite – can be an efficient solid support, enabling the fast and practical architectural (inside / outside) synthesis of stable metal nanoparticles. The obtained halloysite‐nanoparticle composites can be employed as advanced catalysts, ion‐conducting membrane modifiers, inorganic pigments, and optical markers for biomedical studies. Here, we discuss the possibilities to synthesize halloysite decorated with metal, metal chalcogenide, and carbon nanoparticles, and to use these materials in various fields, especially in catalysis and petroleum refinery. [ABSTRACT FROM AUTHOR]

Commercially available BiPh3 was treated with perfluoroalkylphosphinic acids [for example, (C2F5)2P(O)OH] to generate novel, highly Lewis acidic bismuth(III) perfluoroalkylphosphinates of the type Ph xBi[RF2PO2]3− x ( x=0, 1, 2) (RF=-C2F5, -C4F9). The first bismuth(V) perfluoroalkylphosphinate, Ph3Bi[(C2F5)2PO2]2, was synthesized from Ph3BiCl2 and Ag[(C2F5)2PO2]. Examples for the successful application of the catalytically active bismuth(III) and bismuth(V) phosphinates in carbon-carbon bond forming reactions, such as Friedel-Crafts acylation and alkylation, Diels-Alder, Strecker and Mannich reaction, are presented. [ABSTRACT FROM AUTHOR]

Medicinally relevant spirocyclic indolenines, carbazoles and quinolines can each be directly synthesised selectively from common indolyl ynone starting materials by catalyst variation. The high yielding, divergent reactions all proceed by an initial dearomatising spirocyclisation reaction to generate an intermediate vinyl-metal species, which then rearranges selectively by careful choice of catalyst and reaction conditions. [ABSTRACT FROM AUTHOR]

We have described in detail the total synthesis of both the proposed and correct structures of (−)-lyngbyaloside B, which facilitated the elucidation of the complete stereostructure of this natural product. Our study began with the total synthesis of 13-demethyllyngbyaloside B, in which an esterification/ring-closing metathesis (RCM) strategy was successfully used for the efficient construction of the macrocycle. We also established reliable methods for the introduction of the conjugated diene side chain and the l-rhamnose residue onto the macrocyclic framework. However, the esterification/RCM strategy proved ineffective for the parent natural product because of the difficulties in acylating the sterically encumbered C-13 tertiary alcohol; macrolactionization of a seco-acid was also extensively investigated under various conditions without success. We finally completed the total synthesis of the proposed structure of (−)-lyngbyaloside B by means of a macrolactonization that involves an acyl ketene as the reactive species. However, the NMR spectroscopic data of our synthetic material did not match those of the authentic material, which indicated that the proposed structure must be re-examined. Inspection of the NMR spectroscopic data of the natural product and molecular mechanics calculations led us to postulate that the configuration of the C-10, C-11, and C-13 stereogenic centers had been incorrectly assigned in the proposed structure. Finally, our revised structure of (−)-lyngbyaloside B was unambiguously verified through total synthesis. [ABSTRACT FROM AUTHOR]

The oxidative metalation method, involving the interaction of free-base meso-triarylcorroles and W(CO)6 in refluxing decalin, led to a set of three tungsten(VI) biscorroles, the first homoleptic sandwich compounds involving corroles. Single-crystal X-ray structures of two of the complexes revealed square-antiprismatic coordination and strongly domed corroles with long W−N distances of 2.15-2.22 Å and a substantial displacement of ∼1.17 Å of the metal relative to the mean N4 planes of the ligands. The structures correspond to approximate C2 symmetry and are thus chiral. DFT calculations strongly indicate that the enantiomers are configurationally stable and hence amenable to chiral resolution. Their other notable properties include a strongly blueshifted Soret band at (357±2) nm, a relatively intense π→W(d [ABSTRACT FROM AUTHOR]

Assembly of small clusters into rigid bodies with precise shape and symmetry has been witnessed by the significant advances in cluster-based metal-organic frameworks (MOFs), however, nanosized silver cluster based MOFs remain largely unexplored. Herein, two anion-templated silver clusters, CO3@Ag20 and SO4@Ag22, were ingeniously incorporated into a 2D sql lattice ( 1, [CO3@Ag20( iPrS)10(NO3)8(DMF)2] n) and an unprecedented 3D two-fold interpenetrated dia network ( 2, [SO4@Ag22( iPrS)12(NO3)6 ⋅2 NO3] n), respectively, under mild solvothermal conditions. Their atomically precise structures were confirmed by single-crystal X-ray diffraction analysis and further consolidated by IR spectroscopy, thermogravimetric analysis (TGA), and elemental analysis. Each drum-like CO3@Ag20 cluster is extended by twelve NO3− ions to form the 2D sql lattice of 1, whereas each ball-shaped SO4@Ag22 cluster with a twisted truncated tetrahedral geometry is pillared by four [Ag6(NO3)3] triangular prisms to form the 3D interpenetrated dia network of 2. Notably, 2 is the first interpenetrated 3D MOF constructed from silver clusters. These results demonstrate the dual role of the anions, which not only internally act as anion templates to induce the formation of silver thiolate clusters but also externally extend the cluster units into the rigid networks. The photoluminescent and electrochemical properties of 2 are discussed in detail. [ABSTRACT FROM AUTHOR]

The ability of multiple CF3-substituted arenes to act as acceptors for anions is investigated. The results of quantum-chemical calculations show that a high degree of trifluoromethyl substitution at the aromatic ring results in a positive quadrupole moment. However, depending on the polarizability of the anion and on the substitution at the arene, three different modes of interaction, namely Meisenheimer complex, side-on hydrogen bonding, or anion-π interaction, can occur. Experimentally, the side-on as well as a η2-type π-complex are observed in the crystal, whereas in solution only side-on binding is found. [ABSTRACT FROM AUTHOR]

The charging and controlled oxidative doping of single organometallic ferrocene nanoparticles is reported in aqueous sodium tetrafluoroborate using the nano-impacts method. It is shown that ferrocene nanoparticles of approximately 105 nm diameter are essentially quantitatively oxidatively doped with the uptake of one tetrafluoroborate anion per ferrocene molecule at suitably high overpotentials. By using lower potentials, it is possible to achieve low doping levels of single nanoparticles in a controlled manner. [ABSTRACT FROM AUTHOR]

Reaction of Zn(OAc)2 ⋅2 H2O with 2,6-diisopropylphenyl phosphate (dippH2) in the presence of pyridine-4-carboxaldehyde (Py-4-CHO) in methanol resulted in the isolation of a tetrameric zinc phosphate cluster [Zn(dipp)(Py-4-CH(OH)(OMe))]4 ⋅4 MeOH ( 1) with four hemiacetal moieties stabilized on the double-4-ring inorganic cubane cluster. The change of solvent from methanol to acetonitrile leads to the formation of [Zn(dipp)(Py-4-CHO)]4 ( 2), in which the coordinated Py-4-CHO retains its aldehydic form. Dissolution of 1 in CD3CN readily converts it to the aldehydic form and yields 2. Similarly 2, which exists in the aldehyde form in CD3CN, readily converts to the hemiacetal form in CD3OD/CH3OH. Compound 1 is an unprecedented example in which four hemiacetals have been stabilized on a single molecule in the solid state retaining its stability in solution as revealed by its 1H NMR spectrum in CD3OD. The solution stability of 1 and 2 has further been confirmed by ESI-MS studies. To generalize the stabilization of multiple hemiacetals on a single double-four-ring platform, pyridine-2-carboxaldehyde (Py-2-CHO) was used as the auxiliary ligand in the reaction between zinc acetate and dippH2, leading to isolation of [Zn(dipp)(Py-2-CH(OH)(OMe))]4 ( 3). Understandably, recrystallization of 3 from acetonitrile yields the parent aldehydic form, [Zn(dipp)(Py-2-CHO)]4 ( 4). Single-crystal X-ray diffraction studies reveal that supramolecular bonding, aided by hydrogen-bonding interactions involving the hemiacetal functionalities (C−OH, C−OMe, and C−H), are responsible for the observed stabilization. The hemiacetal/aldehyde groups in 1 and 2 readily react with p-toluidine, 2,6-dimethylaniline, and 4-bromoaniline to yield the corresponding tetra-Schiff base ligands, [Zn(dipp)(L)]4 (L=4-methyl- N-(pyridin-4-ylmethylidene)aniline ( 5), 2,6-dimethyl- N-(pyridin-4-ylmethylene)-aniline ( 6), and 4-bromo- N-(pyridin-4-ylmethylene)aniline ( 7)). Isolation of 5- 7 opens up further possibilities of using 1 and 2 as new supramolecular synthons and ligands. [ABSTRACT FROM AUTHOR]

A convergent and highly stereoselective [4+2] cycloaddition of in situ-generated ortho-Quinone methides ( o-QMs) and azlactone enols has been successfully developed through a triple Brønsted acid catalysis strategy. This protocol provides an efficient and mild access to various densely functionalized dihydrocoumarins bearing adjacent quaternary and tertiary stereogenic centers in high yields with excellent diastereo- and enantioselectivity. [ABSTRACT FROM AUTHOR]

The use of a convenient protecting group for boronates allows a selective, catalyzed SN2′ reaction to generate allylboronates which are applied for the synthesis of enantiomerically pure homoallylic alcohols. Depending on the configuration of both catalyst and the protecting group any of the four possible stereoisomers can be formed. The rationale behind the selective addition is supported by density functional theory calculations. [ABSTRACT FROM AUTHOR]

By using a nitrone as the oxidizing directing group, a mild, practical and efficient rhodium(III)-catalyzed CH functionalization for the synthesis of indole derivatives has been developed. This reaction obviates the need for an external oxidant and shows good functional group tolerance. The employment of a sterically hindered Mes group on the carbon center of the nitrone is crucial to produce indoles in high yield. [ABSTRACT FROM AUTHOR]

The synthesis of small organic molecules as probes for discovering new therapeutic agents has been an important aspect of chemical biology. One of the best ways to access collections of small molecules is to use various techniques in diversity-oriented synthesis (DOS). Recently, a new form of DOS, namely 'relay catalytic branching cascades' (RCBCs), has been introduced, wherein a common type of starting material reacts with several scaffold-building agents (SBAs) to obtain structurally diverse molecular scaffolds under the influence of catalysts. Herein, the RCBC reaction of a common type of substrate with SBAs is reported to give two different types of molecular scaffolds and their formation is essentially dependent on the type of catalyst used. [ABSTRACT FROM AUTHOR]

The synthesis of terminal hydroxyl-functionalized oligoethylene is achieved in a two-step one-pot method. Aluminum long chain alkyls (Al-PE) were generated by a catalytic chain transfer reaction involving iron 2,6-bis(imino)pyridyl ligation catalysts and methyl aluminoxane (MAO) aluminum alkyl precursors. At a high catalyst/cocatalyst ratio (>5 000) and a low ethylene pressure (1 bar) the chain transfer to aluminum is the dominant termination step. Discharging oxygen or dry air into the post polymerization reaction mixture leads to aluminum alkoxides (Al-O-PE) and after hydrolysis to hydroxyl-functionalized polyethylene (PE-OH). The degree of oxy-functionalization (up to 88 ± 3%) increased with increasing oxygen pressure and temperature and was more efficient with aluminum alkyls with a lower molecular weight. [ABSTRACT FROM AUTHOR]

Platinum-based catalytic materials have received significant attention, particularly in the shape and size control of faceted materials for . More recently, there has been a rapid increase in the number of reports of successful preparations in this field; however, a fundamental understanding of controlled growth towards catalytic material design is essential for future implementation and broad application. In this review, we provide an overview of the recent findings reported since 2009, focusing on methods for shape control as well as the effects of exposed surface facets on select . Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Ship in a Bottle: The confined synthesis of binary anisotropic nanoparticle catalysts within a hollow support allows for the creation of highly complex new catalyst architectures. [ABSTRACT FROM AUTHOR]