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The ability of α-borylated naphthalene-based aromatic compounds is important because it provides ready access to interesting novel extended π-systems. In this report, we disclose the Ni-catalyzed α-selective C–H borylations of naphthalene-based aromatic compounds. The reaction proceeds with peri-xanthenoxanthene and other aromatic compounds to regioselectively afford the α-borylated products without directing groups. The selectivities of these transformations are different from those of Ir-catalyzed C–H borylation reactions and can be used in a complementary manner.

C–H trifluoromethanesulfonyloxylation (triflation) of 1,1′-bi-2-naphthol (BINOL) derivatives has been established under mild conditions using 1,3-diiodo-5,5-dimethylhydantoin (DIH) and trifluoromethanesulfonic acid (TfOH). Up to eight TfO groups can be introduced in a single operation. The resulting highly oxidized BINOL derivatives can be successfully converted to 8,8′-dihydroxy BINOL and bisnaphthoquinone compounds. Mechanistic studies suggested that C–H triflation occurs in the form of an aromatic substitution reaction via the in situ formation of a radical cation.

Multifunctional catalysts are of great interest in catalysis because their multiple types of catalytic or functional groups can cooperatively promote catalytic transformations better than their constituents do individually. Herein we report a new synthetic route involving the surface functionalization of nanoporous silica with a rationally designed and synthesized dihydrosilane (3-aminopropylmethylsilane) that leads to the introduction of catalytically active grafted organoamine as well as single metal atoms and ultrasmall Pd or Ag-doped Pd nanoparticles via on-site reduction of metal ions. The resulting nanomaterials serve as highly effective bifunctional dehydrogenative catalysts for generation of H2from formic acid.

Polymethylhydrosiloxane has been grafted on the surface of a hierarchically porous silica monolith using a facile catalytic reaction between Si–H and silanol to anchor the polymer. This easy methodology leads to the functionalization of the surface of a silica monolith, where a large amount of free Si–H bonds remain available for reducing metal ions in solution. Palladium nanoparticles of 15 nm have been synthesized homogeneously inside the mesopores of the monolith without any stabilizers, using a flow of a solution containing Pd2+. This monolith was used as column-type fixed bed catalyst for continuous flow hydrogenation of styrene and selective hydrogenation of 3-hexyn-1-ol, in each case without a significant decrease of the catalytic activity after several hours or days. Conversion, selectivity, and stereoselectivity of the alkyne hydrogenation can be tuned by flow rates of hydrogen and the substrate solution, leading to high productivity (1.57 mol g(Pd)−1h–1) of the corresponding cis-alkene.

Enhanced fluorescence detection of metal ions was realized in a system consisting of a fluorescent 2,2′‐bipyridine (BPy) receptor and light‐harvesting periodic mesoporous organosilica (PMO). The fluorescent BPy receptor with two silyl groups was synthesized and covalently attached to the pore walls of biphenyl (Bp)‐bridged PMO powder. The fluorescence intensity from the BPy receptor was significantly enhanced by the light‐harvesting property of Bp‐PMO, that is, the energy funneling into the BPy receptor from a large number of Bp groups in the PMO framework which absorbed UV light effectively. The enhanced emission of the BPy receptor was quenched upon the addition of a low concentration of Cu2+(0.15–1.2×10−6M), resulting in the sensitive detection of Cu2+. Upon titration of Zn2+(0.3–6.0×10−6M), the fluorescence excitation spectrum was systematically changed with an isosbestic point at 375 nm through 1:1 complexation of BPy and Zn2+similar to that observed in BPy‐based solutions, indicating almost complete preservation of the binding property of the BPy receptor despite covalent fixing on the solid surface. These results demonstrate that light‐harvesting PMOs have great potential as supporting materials for enhanced fluorescence chemosensors.

We report that 2,6‐naphthylene‐bridged periodic mesoporous organosilicas exhibit unique fluorescence behavior that reflects molecular‐scale periodicities in the framework. Periodic mesoporous organosilicas consisting of naphthalene–silica hybrid frameworks were synthesized by hydrolysis and condensation of a naphthalene‐derived organosilane precursor in the presence of a template surfactant. The morphologies and meso‐ and molecular‐scale periodicities of the organosilica materials strongly depend on the synthetic conditions. The naphthalene moieties embedded within the molecularly ordered framework exhibited a monomer‐band emission, whereas those embedded within the amorphous framework showed a broad emission attributed to an excimer band. These results suggest that the naphthalene moieties fixed within the crystal‐like framework are isolated in spite of their densely packed structure, different from conventional organosilica frameworks in which only excimer emission was observed for both the crystal‐like and amorphous frameworks at room temperature. This key finding suggests a potential to control interactions between organic groups and thus the optical properties of inorganic/organic hybrids.

The synthesis of three-dimensional (Pm3n) cubic phenylene-bridged hybrid mesoporous silica material using a novel allylorganosilane precursor 1,4-bis(triallylsilyl)phenylene and cetyltrimethylammoniumchloride (C16TMACl) as a structure-directing agent in acidic medium is presented. Sulfonic acid functionalized derivatives of these materials are effective in Friedel–Crafts acylation reactions and in controlling the atmosphere emission of volatile organic compounds, which are responsible for ground level ozone, air toxicity and smog.

Palladium-catalyzed cross-coupling of bipyridine N,N′-dioxide 6,6′-dichloride (Rnap,Rpyr)-1 with the aryl Grignard reagents opened a new approach to axially chiral bipyridine N,N′-dioxides (R)-2 bearing a variety of aryl groups at the 6 and 6′ positions. One of the N,N′-dioxides (R)-2d which is substituted with 3,5-dimethyl-4-methoxy groups was found to be highly catalytically active and enantioselective for the asymmetric allylation of aldehydes with allyl(trichloro)silane. The allylation took place with 0.01–0.1 4;mol 4;% of (R)-2d giving homoallyl alcohols of up to 94% ee.

Chiral “molecular footprint” catalytic cavities were formed on a silica(alumina) gel surface by molecular imprinting with a chiral template, bis(N-benzyloxycarbonyl-l-alanyl)amine. These cavities exhibited stereoselective catalyses in the transacylation of the corresponding substrates: l-, d-, and meso- forms of bis(benzyloxycarbonyl-alanyl) oxide.

“Footprint catalysts” are silica(alumina) gel catalysts with tailored substrate specificities; they are easily prepared by the present authors' molecular imprinting procedures with an appropriate template. Four footprint catalysts were newly prepared by imprinting using p-acetamido-substituted derivatives of benzenesulfonamide and benzamide as templates. They catalyzed transacylations of benzoic anhydride and 4-(acetamido)benzoic benzoic anhydride, respectively. The effects of the acetamido substituents apart from the reaction center on the substrate specificities were investigated.

“Molecular footprint”-like catalytic cavities were marked on a silica(alumina) gel surface by the authors’ molecular imprinting method using a chiral mandelic acid derivative ((−)-(5R)-5-phenyl-2,4-diketo-tetrahydro-oxazole); these chirally imprinted cavities displayed distinct enantioselective catalysis on the transacylation of the corresponding substrates, N-carboxy-(R)-phenylglycine anhydrides and the (S)-isomer.

The authors’ imprinting procedures for “molecular footprint” catalytic cavities on a silica (alumina) gel surface were reinvestigated. The increases of temperature during the incorporation of aluminum ions into the silicate matrix and during the footprint-imprinting with a template remarkably affected the catalytic characteristics of the resulting cavities. A change from room temperature to 75—80 °C increased the catalytic specificities (kcat/Km) by a factor of nearly 50. The results also provided experimental proof for the speculated mechanism of footprint formation. That is, the imprinting comprises precedent Lewis acid site generation on a silicate surface and subsequent Lewis acid–template complexation. The resulting acid–template complexes give rise to the footprint cavities upon removal of the template.

Chiral amines, (R)- and (S)-N-benzyl-a-methylbenzylamine, served as templates in a molecular imprinting we developed. They formed “molecular footprint” cavities on a silica (alumina) gel surface, which showed catalytic activities toward transacylation of benzoic anhydride. The catalyses were susceptible to enantioselective inhibitions by the rebinding of the chiral template amines. This finding proved that the cavities could show chiral recognition through their chirally marked cavity structures.

Trimethylsilylation with hexamethyldisilazane was applied to a surface modification of silica(alumina) gel catalysts, on which surface the “molecular footprint” catalytic cavities had been marked by the authors’ imprinting method. The modification provided for the more stable catalysts than the unmodified catalyst, retaining their molecular-recognition capabilities nearly intact.

Our molecular imprinting procedures were used for molecular footprint cavities formation on the surface of an amorphous clay mineral. The imprinting with a template, N-benzoylsulfonamide, generated footprint cavities on the surface of Japanese Active Clay (sulfuric acid-treated Japanese Acid Clay). The cavities showed specific catalysis toward transacylation of benzoic anhydride that served as a corresponding substrate. This finding provided an experimental clue to study the adsorption mechanism of the Active Clay surface that has hardly been defined so far. Additionally, our comments on the significance of footprint imprinting in chemical evolution are described briefly.

Footprint catalysts are silica(alumina)gel catalysts with tailored specificities. Their catalytic sites are “molecular footprint-like” cavities formed by a molecular imprinting procedure with templates, which are referred to as transition-state or reactive-intermediate analogs of the catalyzed reactions. To clarify the relationship between the structural feature of template molecules and catalytic behavior, seven footprint catalysts were prepared by imprinting with templates of several types closely related to the substrates, benzoic anhydride and acetic anhydride; their catalytic activity and thermodynamic parameters for 2,4-dinitrophenolysis were then estimated. Among these catalysts, a catalyst imprinted with N,N′-dibenzoylbenzenephosphonediamide, a tetrahedral intermediate analog for benzoic anhydride substrate, showed a 10-fold higher catalytic activity than did the other imprinted catalysts.

Imprinting using chiral 5-phenyhydantoins ((5R)- and (5S)-5-pheny-2,4-imidazolinedione) as templates could mark chiral molecular footprint-like cavities on a silica (alumina) gel surface. These cavities displayed evident enantioselective catalyses in reactions of (R)- and (S)-N-carboxyphenylglycine anhydrides, and (R)- and (S)-5-phenylhydantoins with 2,4-dinitrophenolate, respectively. A proposed mechanism and temperature effects on catalysis suggested that the enantioselectivities depended on the binding step of the catalysis.

A tailor-made catalyst design was attempted for a required substrate specificity by the authors’ footprint imprinting method. Two silica(alumina) footprint catalysts were prepared by imprinting with N-benzoylbenzenesulfonamide (1) and N-(p-toluoyl)-p-toluenesulfonamide (2) from the same aluminum ion-doped silica gel. Their catalytic effects upon 2,4-dinitrophenolysis of benzoic anhydride, p-, m-, and o-toluic anhydrides were compared in order to find any difference in substrate specificities. The catalyst prepared by imprinting with 1showed the largest specificity(kcat/Km) toward benzoic anhydride, whereas the catalyst prepared with 2showed the largest specificity toward p-toluic anhydride. This finding evidently demonstrated that the substrate specificities of footprint catalytic sites are alterable, as required through selecting appropriate transition state analogs as template molecules for footprint marking.

Herein, we disclose the Ni-catalyzed ring-opening C–O functionalization of peri-xanthenoxanthenes using Grignard reagents that forms 8-monofunctionalized binaphthols. 1,2-Bis(dicyclohexylphosphino)ethane was the best ligand for alkylations and ICy for arylation. After mechanistic investigations, we assumed that the reaction proceeds via C–O reduction and subsequent C–O functionalization. To verify the mechanism, the intermediate after reduction was isolated. Moreover, the asymmetric addition, using 8-octylbinaphthol after optical resolution, was studied.

We have discovered new Meerwein’s reagent-catalyzed sol–gel polycondensations, which provide highly condensed silica Q4and biphenylylene silica T3as amorphous gels with marginal silanols starting from TEOS and 4,4′-bis(triethoxysilyl)biphenyl (BTEBph), respectively. We propose a plausible pathway for this protocol with possible silyloxonium intermediates.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

For Abstract see ChemInform Abstract in Full Text.

For Abstract see ChemInform Abstract in Full Text.

For Abstract see ChemInform Abstract in Full Text.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.