Suzuki-Miyaura Cross-Coupling Reaction Using Palladium Catalysts Supported on Phosphine Periodic Mesoporous Organosilica.

Phosphine periodic mesoporous organosilicas (R-P-PMO-TMS: R=Ph, tBu), which possess electron-donating alkyl substituents on the phosphorus atom, were synthesized using bifunctional compounds with alkoxysilyl- and phosphino groups, bis[3-(triethoxysilyl)propyl]phenylphosphine borane (1 a) and bis[3-(triethoxysilyl)propyl]-tert-butylphosphine borane (1 b). Immobilization of Pd(0) species was performed to give R-P-Pd-PMO-TMS: R=Ph (2 a), tBu (3 a), respectively. The Pd(0) immobilized 2 a and 3 a were applicable as catalysts for Suzuki-Miyaura cross-coupling reactions of aryl chlorides with phenylboronic acid. It was revealed that 3 a bearing more electron-donating tBu groups exhibited higher catalytic activity. Various functional groups including both electron withdrawing and donating substituents were compatible in the system. The recyclability of 3 a was examined to support its moderate utility for the recycle use.

One-Pot Synthesis of Polymers Containing PC Bonds in the Main Chain.

Placement of phosphorus in the polymer main chain leads to organophosphorus polymers with potentially unique chemical and physical properties. Herein, it is demonstrated that the Abramov phosphonylation reaction can be extended to the synthesis of such polymers, by reacting di- or tricarbaldehydes with phosphinic acid (PA) in the presence of N,O-bis(trimethylsilyl)acetamide (BSA). This technique affords polymers with main chain PC bonds, wherein phosphorus (V), aromatic rings, and hydroxymethylene moieties are linked by bis(α-hydroxymethylene)phosphinic acid (BHMPA) units. The resulting polymers are water soluble, display resilience against acid- and base-catalyzed hydrolysis, and exhibit superior thermal stability with high char yield in air (≈83%) and nitrogen (≈76%) atmosphere.

Square-Planar Anionic Pt0 Complexes.

A T-shaped Pt0 complex with a diphosphine-borane (DPB) ligand was prepared. The Pt→B interaction enhances the electrophilicity of the metal and triggers the addition of Lewis bases to give the corresponding tetracoordinate complexes. For the first time, anionic Pt0 complexes are isolated and structurally authenticated. X-ray diffraction analyses show the anionic complexes [(DPB)PtX]- (X=CN, Cl, Br, I) to be square-planar. The d10 configuration and Pt0 oxidation state of the metal were unambiguously established by X-ray photoelectron spectroscopy and DFT calculations. The coordination of Lewis acids as Z-type ligands is a powerful mean to stabilize elusive electron-rich metal complexes and achieve uncommon geometry.

Selective C-P(O) Bond Cleavage of Organophosphine Oxides by Sodium.

Sodium exhibits better efficacy and selectivity than Li and K for converting Ph3P(O) to Ph2P(OM). The destiny of PhNa co-generated is disclosed. A series of alkyl halides R4X and aryl halides ArX all react with Ph2P(ONa) to produce the corresponding phosphine oxides in good to excellent yields.

Discovery of a New Species of Telenomus (Hymenoptera: Scelionidae) Parasitic on Eggs of Bombyx mandarina and Bombyx mori (Lepidoptera: Bombycidae) in Japan and Taiwan.

We reared a Telenomus species from eggs of Bombyx mandarina (Moore) (Lepidoptera: Bombycidae) and Bombyx mori (Linnaeus) (Lepidoptera: Bombycidae) in Japan, and from eggs of B. mandarina in Taiwan. Morphological examination revealed that this Telenomus species is new to science. In this article, we describe it as Telenomus moricolus Matsuo et Hirose, sp. nov. Because B. mandarina is considered to be an ancestor of B. mori, a domestic insect, it is reasonable to assume that B. mandarina is an original host of T. moricolus. This is the second discovery of an egg parasitoid attacking wild and domesticated silkworms, following the first discovery of T. theophilae, a Chinese species. The significance of the discovery of T. moricolus is discussed in relation to examining the effects of host-insect domestication on egg parasitism.

One-Pot Sequence-Controlled Synthesis of Oligosiloxanes.

Silicones (organopolysiloxanes) have found applications in a wide range of research areas, and their unique and valuable properties have rendered these materials virtually irreplaceable. Despite the fact that silicones have been employed industrially for more than 70 years, synthetic routes to generate silicones remain limited, and the sequence-controlled synthesis of oligo- and polysiloxanes still represents a major challenge in silicone chemistry. Described here is a highly selective sequence-controlled synthesis of linear, branched, and cyclic oligosiloxanes by simple iteration of two reactions, specifically, a B(C6 F5 )3 -catalyzed dehydrocarbonative cross-coupling of alkoxysilanes with hydrosilanes and a B(C6 F5 )3 -catalyzed hydrosilylation of carbonyl compounds, in a single flask. The sequence of the resulting oligosiloxanes can be controlled precisely by the order of addition of the hydrosilane monomers.

PNP-Pincer-Type Phosphaalkene Complexes of Late Transition Metals.

This account summarizes our recent studies on PNP-pincer-type phosphaalkene complexes. Phosphaalkenes with a P=C bond possess an extremely low-lying π* orbital and have a marked tendency to engage in strong π back-bonding with transition metals. This particular ligand property provides PNP-pincer complexes with unique structures and reactivities. 2,6-Bis(phosphaethenyl)pyridine leads to the isolation of coordinatively unsaturated complexes of Fe(I) and Cu(I); the former adopts a trigonal monopyramidal configuration, whereas the latter has a strong affinity for PF6- and SbF6- as non-coordinating anions. Unsymmetrical PNP-pincer-type phosphaalkene complexes of Ir(I) bearing a dearomatized pyridine unit instantly cleave the N-H bond of NH3 and the C-H bond of MeCN at room temperature. The dearomatized iridium complexes catalyze the dehydrative coupling of amines with alcohols to afford N-alkylated amines and imines in high yields.

Development of Nickel Hydrosilylation Catalysts.

In this account, our studies on nickel-catalyzed hydrosilylation reactions are described. A series of (salicylaldiminato)methylnickel complexes efficiently catalyze alkene hydrosilylation under ambient reaction conditions. Commercially available Ni(II) salts, Ni(acac)2 (acac = acetylacetonato) and its derivatives bis(hexafluoroacetylacetonato)nickel(II) and bis (2,2,6,6-tetramethyl-3,5-heptanedionato)nickel(II), also act as versatile hydrosilylation catalyst precursors in the presence of NaBHEt3 . These systems catalyze the hydrosilylation of various alkenes such as industrially important siloxy-, amino-, and epoxy-substituted ones. The arene-supported cationic nickel allyl complexes also serve as good catalysts for alkene hydrosilylation at room temperature. These nickel complexes exhibit high selectivity towards the reaction using secondary hydrosilanes. Mechanistic studies based on experiments and DFT calculations support a novel mechanism, which includes a facile Si-H bond cleavage and a Si-C bond formation, assisted by the cooperative action of the allyl ligand.

A novel cluster of mariner-like elements belonging to mellifera subfamily from spiders and insects: implications of recent horizontal transfer on the South-West Islands of Japan.

Mariner-like elements (MLEs) have been isolated from various eukaryotic genomes and they are divided into 15 subfamilies, including main five subfamilies: mauritiana, cecropia, mellifera/capitata, irritans, and elegans/briggsae. In the present study, MLEs belonging to mellifera subfamily were isolated from various spiders and insects (Hymenoptera and Lepidoptera) inhabiting the South-West Islands of Japan and neighboring regions. MLEs isolated from 15 different species formed a distinct novel cluster in mellifera subfamily. MLEs obtained from three different species [i.e., the bee Amegilla senahai subflavescens (Amsmar1), the wasp Campsomeris sp. (Casmar1), and the swallowtail butterfly Pachliopta aristolochiae (Paamar1)] contained an intact open reading frame that encoded a putative transposase. These transposases exhibited high similarity of 97.9% among themselves. In case of Casmar1, the presence of an intact ORF was found in high frequencies (i.e., 11 out of 12 clones). In addition, these transposases also showed the presence of a terminal inverted repeat-binding motif, DD(34)D and two highly conserved amino acid motifs, (W/L)(I/L)PHQL and YSP(D/N)L(A/S)P. These two motifs differed from previously known motifs, WVPHEL and YSPDLAP. MLEs isolated from these three different species may have been inserted into their genomes by horizontal transfer. Furthermore, the presence of an intact ORF suggests that they are still active in habitats along these isolated islands.

Ester hydrogenolysis via ß-C-O bond cleavage catalysed by a phenanthroline-based PNNP-cobalt(I) complex.

A Co(I) catalyst bearing a phenanthroline-based PNNP ligand (2,9-bis((diphenylphosphanyl)methyl)-1,10-phenanthroline) exhibits long-range metal ligand cooperation behavior using a ligand backbone as a hydrogen reservoir and catalyses hydrogenolysis of benzyl benzoate derivatives via ß-C-O cleavage with atmospheric pressure H2.

Catalytic thiolation-depolymerization-like decomposition of oxyphenylene-type super engineering plastics via selective carbon-oxygen main chain cleavages.

As the effective use of carbon resources has become a pressing societal issue, the importance of chemical recycling of plastics has increased. The catalytic chemical decomposition for plastics is a promising approach for creating valuable products under efficient and mild conditions. Although several commodity and engineering plastics have been applied, the decompositions of stable resins composed of strong main chains such as polyamides, thermoset resins, and super engineering plastics are underdeveloped. Especially, super engineering plastics that have high heat resistance, chemical resistance, and low solubility are nearly unexplored. In addition, many super engineering plastics are composed of robust aromatic ethers, which are difficult to cleave. Herein, we report the catalytic depolymerization-like chemical decomposition of oxyphenylene-based super engineering plastics such as polyetheretherketone and polysulfone using thiols via selective carbon-oxygen main chain cleavage to form electron-deficient arenes with sulfur functional groups and bisphenols. The catalyst combination of a bulky phosphazene base P4-tBu with inorganic bases such as tripotassium phosphate enabled smooth decomposition. This method could be utilized with carbon- or glass fiber-enforced polyetheretherketone materials and a consumer resin. The sulfur functional groups in one product could be transformed to amino and sulfonium groups and fluorine by using suitable catalysts.

Depolymerization of Polyester Fibers with Dimethyl Carbonate-Aided Methanolysis.

Polyester fibers, comprising mostly poly(ethylene terephthalate) with high crystalline content, represent the most commonly produced plastic for ubiquitous textiles, and approximately 60 million tons are manufactured annually worldwide. Considering the social issues of mismanaged waste produced from used textile products, there is an urgent demand for sustainable waste polyester fiber recycling methods. We developed a low-temperature, rapid, and efficient depolymerization method for recycling polyester fibers. By utilizing methanolysis with dimethyl carbonate as a trapping agent for ethylene glycol, depolymerization of polyester fibers from textile products proceeded at 50 °C for 2 h, affording dimethyl terephthalate (DMT) in a >90% yield. This strategy allowed us to depolymerize even practical polyester textiles blended with other fibers to selectively isolate DMT in high yields. This method was also applicable for colored polyester textiles, and analytically pure DMT was isolated via depolymerization and decolorization processes.

Facile N-H bond cleavage of ammonia by an iridium complex bearing a noninnocent PNP-pincer type phosphaalkene ligand.

A novel PNP-pincer type phosphaalkene complex of iridium bearing a dearomatized pyridine unit (3) has been prepared. Complex 3 rapidly reacts with ammonia at room temperature to afford a parent amido complex in high yield. DFT calculations indicate that the phosphaalkene unit with a strong π-accepting property effectively facilitates the N-H bond cleavage of ammonia via metal-ligand cooperation.

Biogeography revealed by mariner-like transposable element sequences via a Bayesian coalescent approach.

Genetic diversity of natural populations is useful in biogeographical studies. Here, we apply a Bayesian method based on the coalescent model to dating biogeographical events by using published DNA sequences of wild silkworms, Bombyx mandarina, and the domesticated model organisms B. mori, both of which categorized into the order of Lepidoptera, sampled from China, Korea, and Japan. The sequences consist of the BmTNML locus and the flanking intergenic regions. The BmTNML locus is composed of cecropia-type mariner-like element (MLE) with inverted terminal repeats, and three different transposable elements (TE), including L1BM, BMC1 retrotransposons, and BmamaT1, are inserted into the MLE. Based on the genealogy defined by TE insertions/deletions (indels), we estimated times to the most recent common ancestor and these indels events using the flanking, MLE, and indels sequences, respectively. These estimates by using MLE sequences strongly correlated with those by using flanking sequences, implying that cecropia-type MLEs can be used as a molecular clock. MLEs are thought to have transmitted horizontally among different species. By using a pair of published cecropia-type MLE sequences from lepidopteran insect, an emperor moth, and a coral in Ryukyu Islands, we demonstrated dating of horizontal transmission between species which are distantly related but inhabiting geographically close region.

Mos1 transposon-based transformation of fish cell lines using baculoviral vectors.

Drosophila Mos1 belongs to the mariner family of transposons, which are one of the most ubiquitous transposons among eukaryotes. We first determined nuclear transportation of the Drosophila Mos1-EGFP fusion protein in fish cell lines because it is required for a function of transposons. We next constructed recombinant baculoviral vectors harboring the Drosophila Mos1 transposon or marker genes located between Mos1 inverted repeats. The infectivity of the recombinant virus to fish cells was assessed by monitoring the expression of a fluorescent protein encoded in the viral genome. We detected transgene expression in CHSE-214, HINAE, and EPC cells, but not in GF or RTG-2 cells. In the co-infection assay of the Mos1-expressing virus and reporter gene-expressing virus, we successfully transformed CHSE-214 and HINAE cells. These results suggest that the combination of a baculovirus and Mos1 transposable element may be a tool for transgenesis in fish cells.

Oxidative Depolymerization of Polyphenylene Oxide into Benzoquinone.

Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) is one of the most important engineering plastics commonly utilized in various fields. Herein, chemical recycling of PPO was performed via oxidative depolymerization to form 2,6-diemthyl-p-benzoquionone (26DMBQ) as a sole aromatic product in 66 % yield using nitronium ions (NO2 + ) as a mild oxidant. Mechanistic studies revealed that PPO is oxidized by NO2 + generated from the combination of a silicotungstic acid and nitrate salts, and then subsequently attacked by H2 O to achieve C-O bond cleavage, resulting in the formation of 26DMBQ, which was sublimed at the headspace of the reaction vessel in pure form. 26DMBQ was applied to polymerization with dianilines to form polyimides. Thus, an upgrade recycling process of PPO was demonstrated.

Depolymerization of robust polyetheretherketone to regenerate monomer units using sulfur reagents.

Super engineering plastics, high-performance thermoplastic resins such as polyetheretherketone, and polyphenylene sulfide have been utilized in industries, owing to their high thermal stability and mechanical strength. However, their robustness hinders their depolymerization to produce monomers and low-weight molecules. Presently, chemical recycling for most super engineering plastics remains relatively unexplored. Herein, we report the depolymerization of insoluble polyetheretherketone using sulfur nucleophiles via carbon-oxygen bond cleavages to form benzophenone dithiolate and hydroquinone. Treatment with organic halides converted only the former products to afford various dithiofunctionalized benzophenones. The depolymerization proceeded as a solid-liquid reaction in the initial phase. Therefore, this method was not affected by the shape of polyetheretherketone, e.g., pellets or films. Moreover, this depolymerization method was applicable to carbon- or glass fiber-enforced polyetheretherketone material. The depolymerized product, dithiofunctionalized benzophenones, could be converted into diiodobenzophenone, which was applicable to the polymerization.

Hydroxylation-Depolymerization of Oxyphenylene-Based Super Engineering Plastics To Regenerate Arenols.

Super engineering plastics, high-performance thermoplastic resins, show high thermal stability and mechanical strength as well as chemical resistance. On the other hand, chemical recycling for these plastics has not been developed due to their stability. This study describes depolymerization of oxyphenylene super engineering plastics via carbon-oxygen main chain cleaving hydroxylation reaction with an alkali hydroxide nucleophile. This method is conducted with cesium hydroxide as a hydroxy source and calcium hydride as a dehydration agent in 1,3-dimethyl-2-imidazolidinone, which provides hydroxylated monomers effectively. In the case of polysulfone, both 4,4'-sulfonyldiphenol (bisphenol S) and 4,4'-(propane-2,2-diyl)diphenol (bisphenol A) were obtained in high yields. Other super engineering plastics such as polyethersulfone, polyphenylsulfone, and polyetheretherketone were also applicable to this depolymerization.

Borane-Protecting Strategy for Hydrosilylation of Phosphorus-Containing Olefins.

Ir-catalyzed hydrosilylation of the alkenyl phosphine borane complex 1 was achieved to give the corresponding products 2. Because the phosphino group coordinates with metals and is unstable under aerobic conditions, the formation of the corresponding borane adduct was effective not only to promote the target hydrosilylation but also to keep 1 stable under aerobic conditions. The removal of coordinated borane from 2 was readily performed with the treatment by 1,4-diazabicyclo[2.2.2]octane to apply to further transformations. The immobilization and following deprotection of 2 on the surface of mesoporous silica were also examined.

Female sex pheromone and male behavioral responses of the bombycid moth Trilocha varians: comparison with those of the domesticated silkmoth Bombyx mori.

Analysis of female sex pheromone components and subsequent field trap experiments demonstrated that the bombycid moth Trilocha varians uses a mixture of (E,Z)-10,12-hexadecadienal (bombykal) and (E,Z)-10,12-hexadecadienyl acetate (bombykyl acetate) as a sex pheromone. Both of these components are derivatives of (E,Z)-10,12-hexadecadienol (bombykol), the sex pheromone of the domesticated silkmoth Bombyx mori. This finding prompted us to compare the antennal and behavioral responses of T. varians and B. mori to bombykol, bombykal, and bombykyl acetate in detail. The antennae of T. varians males responded to bombykal and bombykyl acetate but not to bombykol, and males were attracted only when lures contained both bombykal and bombykyl acetate. In contrast, the antennae of B. mori males responded to all the three components. Behavioral analysis showed that B. mori males responded to neither bombykal nor bombykyl acetate. Meanwhile, the wing fluttering response of B. mori males to bombykol was strongly inhibited by bombykal and bombykyl acetate, thereby indicating that bombykal and bombykyl acetate act as behavioral antagonists for B. mori males. T. varians would serve as a reference species for B. mori in future investigations into the molecular mechanisms underlying the evolution of sex pheromone communication systems in bombycid moths.