Catalytic reactions involving the cleavage of carbon-cyano and carbon-carbon triple bonds

The catalytic reactions that involve the cleavage of C-CN bonds and carbon-carbon triple bonds are described in this tutorial review. Regarding the cleavage of a C-CN bond, the catalytic reaction can proceed by two different mechanisms: oxidative addition and deinsertion of silyl isocyanide. A carbon-carbon triple bond can be cleaved in the absence of an organic promoter via the formation of unique organometallic species, such as allenylidene and cyclopropyl carbenoid complexes.     

Electron transfer promoted regioselective ring-opening reaction of cyclopropyl silyl ethers

Oxidative ring-opening reactions of cyclopropyl silyl ethers incorporated into bicyclo[m.1.0]alkane framework were investigated. The results show that the regioselectivities for ring-opening of intermediate radical cations, formed by single electron transfer, are governed by the nature of the nucleophile as well as oxidizing species.     

Non-Abelian duality from vortex moduli: A dual model of color-confinement

It is argued that the dual transformation of non-Abelian monopoles occurring in a system with gauge symmetry breaking G→H is to be defined by setting the low-energy H system in Higgs phase, so that the dual system is in confinement phase. The transformation law of the monopoles follows from that of monopole-vortex mixed configurations in the system (with a large hierarchy of energy scales, v₁v₂) , under an unbroken, exact color-flavor diagonal symmetry . The transformation property among the regular monopoles characterized by π₂(G/H), follows from that among the non-Abelian vortices with flux quantized according to π₁(H), via the isomorphism π₁(G)π₁(H)/π₂(G/H). Our idea is tested against the concrete models—softly-broken supersymmetric SU(N), SO(N) and USp(2N) theories, with appropriate number of flavors. The results obtained in the semiclassical regime (at v₁v₂Λ) of these models are consistent with those inferred from the fully quantum-mechanical low-energy effective action of the systems (at v₁,v₂Λ).     

Photografting and patterning of oligonucleotides on benzophenone-modified boron-doped diamond

Irradiation of a patterned benzophenone-terminated boron-doped diamond (BDD) surface with UV light (lambda = 350 nm) in the presence of a 15(mer) oligonucleotide resulted in the covalent linking of the DNA strand to the BDD interface.     

Nickel-Catalyzed Suzuki-Miyaura Cross-Coupling Involving C−O Bond Activation

An efficient Suzuki-Miyaura cross-coupling reaction of ortho-phenoxy-substituted aromatic amides with aryl boronates is described. The use of LiO^tBu is crucial for the success of the reaction. An amidate anion, which is formed through deprotonation of the amide NH bond by LiO^tBu, functions as a directing group to activate a C−O bond.     

Synthesis and properties of high birefringence liquid crystals: thiophenylacetylene and benzothiazolylacetylene derivatives

We have synthesized and evaluated the physical properties of thiophenylacetylene and benzothiazolylacetylene derivatives in order to obtain higher Δn liquid crystals as compared with analogous phenylacetylene-based compounds. These new materials had poorer liquid crystallinity than the phenylacetylene derivatives. Exchanging the phenyl ring for a benzothiazole ring was effective in increasing Δn, whereas a thiophene ring decreased Δn because of the associated reduction in the anisotropic polarizability. These conjugated hetero rings shifted the UV absorption spectra into the visible region such that they are yellow or brownish in colour.     

Composition dependences of Tc,Jc, physical property and crystal structure of Bi1.8Pb0.3Sr2.0Ca0.9Y0.1Cu2.0−xMxOy (M = Zr,Zn) superconducting oxide

In this study, we focused on bulks and thin films of Bi_1.8Pb_0.3Sr_2.0Ca_0.9Y_0.1Cu_2.0O_y, and replaced Cu by Zr⁴⁺ and Zn²⁺. From the electrical conductivity measurements on the bulk samples, it was found that T_c became higher by a partial substitution of Zr⁴⁺, and exhibited a maximum value in the sample with the Zr⁴⁺ content of 0.05. On the other hand, T_c was decreased by the Zn²⁺ substitution. These results suggested that it was possible to control a carrier concentration by the Zr- and Zn-substitutions. Indeed, an average valence of the Cu, determined by a chelate titration, was changed by these substitutions. Similar tendency of the superconducting properties was also observed in the case of the film samples. In order to investigate crystal structures in detail, we measured neutron diffraction patterns, and then performed the Rietveld analysis. As a result, it was clarified that the (Cu, Zr)–O2 layers became flat by the Zr-substitution. Such a structure change may be one of the reasons why the substitution improved the superconducting properties.     

RAFT‐approach to well‐defined telechelic vinyl polymers with hydroxyl terminals as polymeric diol‐type building blocks for polyurethanes

A new trithiocarbonate 1 bearing two hydroxyl moieties was synthesized and employed as a RAFT agent for radical polymerization of vinyl monomers. 1 mediated RAFT polymerizations of styrene and ethyl acrylate to give the corresponding polymers with predictable molecular weights and narrow molecular weight distributions. Structural analyses of the polymers with NMR and MALDI‐TOF mass techniques revealed that they were telechelic ones, of which both chain ends were endowed with hydroxyl groups inherited from trithiocarbonate 1 . Usefulness of these telechelic polymers as polymeric diol‐type building blocks was demonstrated in their polyaddition with diisocyanates, which gave the corresponding polyurethanes. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013