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The enhanced catalytic activity of ruthenium complex-bound norvaline Boc-L-[Ru]Nva-OMe 1, in which the ONO-pincer ruthenium complex Ru(pydc)(terpy) 2 is tethered to the α-side chain of norvaline, has been demonstrated for the oxidation of methoxybenzenes to p-benzoquinones with a wide scope of substrates and unique chemoselectivity.

The title agent and its Pd complex act as a general surfactant: hydrophobic oily substrates are emulsified in water and thus, an acceleration of the reaction becomes possible under heterogeneous conditions.

An efficient, regioselective synthesis of fluorine-substituted arylboronic esters was achieved through fluorine-controlled C–H borylation of arenes with diboron catalyzed by a PSiN–platinum complex. The promising utility of the PSiN–platinum catalyst and its unique regioselectivity were demonstrated for the first time, which would complement the well-developed Ir-catalyzed C–H borylation.

Selective oxovanadium(V)-induced cross-coupling between boron and silyl enolates yields unsymmetrical 1,4-diketones.

offering a practical alternative to conventional nickel- and palladium-catalyzed aryl-alkyl couplings

Use of formate salts as a hydride as well as a CO2 source was achieved in a PGeP-palladium complex-catalyzed hydrocarboxylation of allenes through a highly efficient decarboxylation–carboxylation process. This reaction proceeds under mild conditions and provides an alternative strategy for utilizing formate salts as a C1 source.

A straightforward synthesis of 1,2-dicyanoalkanes by reacting nitroalkenes with trimethylsilyl cyanide in the presence of tetrabutylammonium fluoride is described.

Optimum reaction conditions are examined for the intramolecular ring closing C—N bond formation affording six 5,10-diaryl-5,10-dihydrophenazines of type (II).They can find potential use as hole-injection materials in organic electroluminescence devices.

Direct carboxylation of simple arenes under atmospheric pressure of CO2 is achieved through a rhodium-catalyzed C–H bond activation without the assistance of a directing group. Various arenes such as benzene, toluene, xylene, electron-rich or electron-deficient benzene derivatives, and heteroaromatics are directly carboxylated with high TONs.

The title catalytic system exhibits high activity and selectivity for the epoxidation of alkenes.

3-Iodo-2-propenylindoles (I) are easily prepared from corresponding indole-2-carbaldehydes and vinyl Grignard reagents.

Dehydrogenative borylation of alkenes and 1,3-dienes was realized by carrying out the reaction in the presence of bis(pinacolato)diboron (B2pin2) and a catalytic amount of PSiP-pincer palladium com...

Oxovanadium(V)-induced oxidative coupling of (Z)-boron enolates derived from enones (I) is demonstrated to give the corresponding 2,3-disubstituted 1,4-diketones (II) in good yields.

The reaction of dithioacetals with excess aqueous hydrogen peroxide in the presence of catalytic amounts of iron(III) acetylacetonate and sodium iodide efficiently produces the corresponding carbonyl compounds in high yields.

Pd-catalyzed direct carboxylation of alkenyl C–H bonds with carbon dioxide was realized for the first time. Treatment of 2-hydroxystyrenes and a catalytic amount of Pd(OAc)2 with Cs2CO3 under atmospheric pressure of CO2 afforded corresponding coumarins in good yield. Furthermore, isolation of the key alkenylpalladium intermediate via C–H bond cleavage was achieved. The reaction was proposed to undergo reversible nucleophilic addition of the alkenylpalladium intermediate to CO2.

The key to the success of this novel protocol is the use of in situ generated magnesium amides in the presence of a lithium halide, which dramatically increases the product yield.

Acylcobalt species generated by treatment of alkyne—[Co2(CO)6] complexes with a combination of AcOH and pyridine as promoter, undergo addition reactions with various alkenes to give the corresponding alkyl alkenyl ketones instead of Pauson—Khand products.

The known PSiP-pincer palladium(II) complex (Ia) and the novel synthesized germanium (Ib) and tin (Ic) analogues are applied as catalysts to a reductive aldol-type reaction.

Three- and four-component reactions towards functionalized esters, lactones and lactames are developed based on palladium/light induced, radical carbonylation reactions.

Bis(boronate) compounds have been attracting much attention as versatile building blocks for concise synthesis of complex molecules because these compounds enable multiple C–C bond formations and functionalizations at the C–B bonds. Transition metal-catalyzed diboration reactions of unsaturated hydrocarbons with diborons have been utilized as a straightforward and highly useful method for the synthesis of bis(boronate) compounds. This perspective article will summarize recent development in substrate generality, asymmetric synthesis, and discovery of new metal catalysts in the diboration chemistry. Moreover, another approach to bis(boronate) compounds via sequential monoborylation reaction will also be described, expanding diversity of the direct synthesis of bis(boronate) compounds.

A xerogel derived from the supramolecular gel of NHC-pincer Pd-complex-bound norvaline shows high catalytic activity for the intramolecular addition-cyclization of alkynoic acid and phenol derivatives in water furnishing ene-lactones in good to excellent yields.

Intramolecular [2+2] cycloaddition of γ,δ-unsaturated ketenes derived from hex-5-enoyl chloride derivatives gave bicyclo[2.1.1]hexan-5-ones with complete regioselectivity.

An iron(II) chloride complex possessing a sterically demanding ortho-phenylene-tethered bisphosphine ligand shows a high catalytic activity in the Kumada–Tamao–Corriu coupling of nonactivated alkyl...

Dye-sensitized solar cells (DSCs) are photoelectrochemical cells consisting of mesoporous TiO2 electrodes sensitized with organic dyes such as ruthenium dyes, Pt counter-electrodes, and I−/I3− redox electrolytes. Increasing the durability and power conversion efficiency of DSCs are critical goals that will have to be met before DSCs can be put on the market on a large scale. For increasing durability, we have developed new gel-type polymeric solid electrolytes (PSEs) based on poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) to reduce leakage of the electrolyte solution, which is one of the main factors of poor DSC durability. The use of PSEs, however, is almost always accompanied by a decrease in the short-circuit current density (Jsc). We then studied the electrochemical properties of two different kinds of DSCs to determine why the conversion efficiency is lower in PSE-based DSCs than in liquid electrolyte-based DSCs. The diffusion coefficient of I3− and the cell-gap (the distance between the surface of the transparent conducting oxide substrate for the TiO2 electrode and that of the Pt counter-electrode) of DSCs were eventually understood to be key factors affecting the Jsc. This indicates that the design of the DSC structure is quite important for achieving higher conversion efficiency in a PSE-based DSC. Further, with the aim of increasing the power conversion efficiency, we have developed ultrahigh-aspect-ratio TiO2 nanotubes (TNTs), made by anodic oxidation of Ti metals in an extremely dilute perchloric acid solution, to establish good carrier pathways. Unlike TiO2 nanoparticles (NPs), TNTs of suitable dimensions serve as efficient light scatterers while also providing large surface areas for charge separation. We have succeeded in enhancing the power conversion efficiency of a DSC using a TiO2 electrode with a new bilayer structure, which consists of a light-scattering TNT layer formed upon a light-absorbing NP layer. We also found a promising application for TNTs formed on Ti substrates, i.e. their use in the fabrication of flexible, back-side illuminated DSCs. In this review we present our recent research on DSCs fabricated with PVDF-HFP-type PSEs and ultrahigh-aspect-ratio TNTs.

Electronically activated alkenes, nonelectronically activated, sterically less demanding alkenes as well as cyclooctene are selectively diborylated under catalysis of palladium complexes (Ia) or (Ib).

Rh-catalyzed direct carboxylation of unactivated aryl C−H bond under atmospheric pressure of carbon dioxide was realized via chelation-assisted C−H activation for the first time. Variously substituted and functionalized 2-arylpyridines and 1-arylpyrazoles underwent the carboxylation in the presence of the rhodium catalyst and a stoichiometric methylating reagent, AlMe2(OMe), to give carboxylated products in good yields. The catalysis is proposed to consist of methylrhodium(I) species as the key intermediate, which undergoes C−H activation to afford rhodium(III), followed by reductive elimination of methane to give nucleophilic arylrhodium(I). This approach demonstrates promising application of C−H bond activation strategy in the field of carbon dioxide fixation.

The reaction is efficiently catalyzed by the PSiP-pincer-type palladium catalyst and proceeds stereoselectively even when isomeric mixtures are used as substrates.

The Shi-type epoxidation of O-tert-butyldiphenylsilyl (TBDPS) protected o-allylphenols serves as an efficient strategy to construct the dihydrobenzofurans and dihydrobenzopyrans in up to 97% ee. This methodology led to the enantioselective synthesis of (+)-marmesin, (−)-(3′R)-decursinol, and (+)-lomatin.

An efficient method for the stereoselective synthesis of tetracyclic spirolactams is presented.

A well-defined organoaluminum “ate” complex is proposed as active species in the title Fe-catalyzed cross-coupling reaction.

A novel iron-catalyzed Suzuki—Miyaura coupling of nonactivated alkyl halides with arylboron compounds is developed.

Photoinduced Pd-catalyzed three-component coupling of terminal alkynes with alkyl iodides and carbon monoxide tolerates a wide range of functional groups.

Titanacyclic compounds of the formula Cp*2Ti(CH2CH2C(CH2CHR)CH2) (5a; R=H and 5b; R=C6H5, Cp*=pentamethylcyclopentadienyl), the first stable titanacyclopentanes, have been prepared by the reaction of bis(pentamethylcyclopentadienyl)titanium–ethylene complex (3) with methylenecyclopropanes (4), and their structures were determined based on both spectroscopic data and X-ray crystallography. Complex 5b crystallized in space group P21⁄a(Z=4) with cell constants, a=21.832(3), b=8.580(1), c=14.759(2) A, β=96.81(1)°, U=2744.9(6) A3 (4261 reflections, R=0.053). The reaction of 5 with carbon monoxide afforded spiro[2.4]heptan-5-ones in 98% yield. The thermal decomposition of 5 has been investigated, and possible mechanisms of the reactions have been proposed based on deuterium-labeled experiments. A novel formal reductive elimination of organic ligands giving 1-phenylspiro[2.4]hexane has been observed in the thermolysis of 5b. A structure–reactivity relationship has been discussed.

Organotin-aided three component couplings of C=N double bonds with 2,4-pentadienyl and α,β-unsaturated acyl groups followed by intramolecular Diels–Alder reactions result in highly stereoselective ...

Chiral cationic and neutral Rh complexes RhX(bichep)(nbd) (XCl,ClO 4 ; nbd=norbornadiene;bichep=2,2′-bis(dicyclohexylphosphino)-6,6′-dimethyl-1,1′-biphenyl) are highly active and excellent catalysts for enantioselective hydrogenation of prochiral olefins and ketones under mild reaction conditions.

Photocatalytic asymmetric reduction of 3-methyl-2-oxobutanoic acid giving 2-hydroxy-3-methylbutanoic acid has been carried out in up to 60% ee in aqueous methanol with chiral BINAP–Rh(I) complexes and semiconductor photocatalysts, TiO2 or CdS.

Three pairs of new axially dissymmetric diphosphine ligands, (R)-(−)- and (S)-(+)-2,2′-bis(dicyclohexyl-phosphino)-1,1′-binaphthyl [(R)-(−)- and (S)-(+)-Cy-BINAP], (R)-(+)- and (S)-(−)-2,2′-bis(diphenylphosphino)-5,5′,-6,6′,7,7′,8,8′-octahydro-1,1′-binaphthyl [(R)-(+)- and (S)-(−)-H 8 -BINAP], and (R)-(−)- and (S)-(+)-2,2′-bis(dicyclohexyl-phosphino)-5,5′,6,6′,7,7′,8,8′-octahydro-1,1′-binaphthyl [(R)-(−)- and (S)-(+)-Cy-H 8 -BINAP], have been synthesized and their absolute configurations have been determined on the basis of an X-ray analysis and CD spectra.

The cycloaddition reaction of 3-styryl-1,2-thia phosphole 2-sulfide and 1,5-diphenyl-2,4-pentadiene-1-thione derivatives generated by the thermolysis of 5,6-distyryl-3,8-diaryl-2,9-dithia-1-phosphabicyclo[4.3.0]nona-3,7-diene 1-sulfides have been described. Methacrylonitrile, methyl methacrylate, α-methylstyrene, norbornene, methyl acrylate, styrene, and mehyl vinyl ketone afforded the cycloadducts or their rearranged products with the thiaphosphole 2-sulfides, whereas diethyl azodicarboxylate, dimethyl acetylenedicarboxylate, and N-(p-methoxyphenyl)maleimide gave the cycloadducts with the thioketone.