Selective double hydrosilylation and double hydroborylation were achieved by using tertiary and secondary silanes and pinacolborane with an organonitrile (RC≡N; R=alkyl, aryl) in the presence of a catalytic amount of an iron complex containing indium trihalide [Fe(MeCN)₆][cis-Fe(CO)₄(InX₃)₂], prepared by the reaction of [Fe₃(CO)₁₂] with InX₃ (X=Cl, Br, I). In both reactions two silyl groups and two boryl groups made bonds selectively with only the nitrogen atom. In addition, this catalytic system could be adaptable to an unprecedented one-pot synthesis of borylsilylamine via catalytic hydrosilylation and hydroborylation of organonitrile. These are novel reports of the combination of a transition-metal complex and an indium source in organic synthesis.

The bromination reaction of organic compounds is one of the important reactions in organic synthesis, providing bromination products which are key precursors for various transformations. Conventional bromination reaction is carried out using toxic and hazardous elemental bromine. Oxidative bromination reaction by utilization of a bromide ion as a bromide source instead of bromine has attracted a great deal of attention to develop environmentally friendly bromination method. In this account, catalytic oxidative halogenation and aromatization by using halide salt as a halide source are described. An environmentally benign catalytic oxidative bromination reaction was demonstrated by the combination of the redox properties of a commercially available inexpensive vanadium compound and molecular oxygen as a terminal oxidant, wherein vanadium-catalyzed oxidative bromination was promoted by Brønsted acid or Lewis acid. The catalytic chlorination reaction of ketones and alkenes was achieved by using a vanadium catalyst in the presence of Bu₄NI and AlCl₃ under molecular oxygen. The vanadium-catalyzed oxidation system, which consists of a vanadium catalyst, a bromide source, and an acid under molecular oxygen, could be applied to the catalytic oxidative aromatization of 2-cyclohexen-1-ones, affording the corresponding phenol derivatives. Metal-free oxidative bromination reactions was also performed in aqueous media under mild conditions with a combination of tetrabutylammonium bromide as a bromide source, trifluoroacetic acid as an acid, and hydrogen peroxide as an oxidant.

Self-assembled supramolecular architectures of amphiphilic diarylethenes featuring tri(ethylene glycol) monomethyl ether chains showed photoinduced macroscopic morphological change upon alternate irradiation with UV and visible light in water. These suspensions containing supramolecular assembly of the diarylethene showed absorption spectral shifts at temperatures corresponding to the lower critical solution temperature (LCST) transition. The photoreversible morphological transformation can be rationalized as the photoinduced phase transition between the high- and low-temperature phases of the LCST transition. Colorless microspheres of the open-ring isomer had bicontinuous coacervate structures. The closed-ring isomers became hydrated state and formed rod-like micelle and bilayer structures depending on intermolecular interaction. The photoinduced change in nanostructure enables application to sophisticated photoactuators in aqueous media. The nanofibers formed bundles in a methylcellulose aqueous solution by depletion force. A submillimeter-sized bundle showed a photoinduced shrinking of more than 100 µm under visible light irradiation. Elongation of the fiber was observed in the direction of linearly polarized light. The diffusive motion was suppressed in the direction perpendicular to that of the generated fiber, as revealed by means of trajectory tracking of added polystyrene beads. Photoinduced clustering of polystyrene beads and photocontrol of their diffusion was achieved with thermal convection and assistance of the change in supramolecular architectures.

Aggregation of peptide/protein is intimately related to a number of human diseases. More than twenty have been identified to aggregate into fibrils containing extensive β-sheet structures, and species generated in the aggregation processes (i.e., oligomers, protofibrils, and fibrils) contribute to disease development. Amyloid-β (designated Aβ), related to Alzheimer disease (AD), is the representative example. Artificial chemical transformation of toxic, aberrant Aβ to less toxic forms at the disease site might be a new candidate for AD treatment. Thus, covalent installation of hydrophilic oxygen atoms to Aβ using aerobic oxygen and visible light as oxygen atom- and energy sources, respectively, in the presence of a catalyst (i.e., catalytic photooxygenation) was used. Selective, cell-compatible photo-oxygenation of Aβ by a flavin catalyst attached to an Aβ-binding peptide markedly decreased aggregation potency and neurotoxicity of Aβ. In addition, we designed photooxygenation catalysts that can be turned on only when binding with the higher-order structures of amyloid aggregates. This on/off switchable activity of the catalyst that senses amyloid structure enabled highly Aβ-selective oxygenation in the presence of other bioactive peptides and living cells. Moreover, we succeeded to develop next-level switchable oxygenation catalysts that can be activated by a near-infrared light. The catalyst induced photooxygenation of Aβ in the brains of living mice, leading to significant reduction of Aβ in the brain.

The major target in the pharmacological treatment for acid related diseases is the gastric proton pump enzyme H⁺,K⁺-ATPase which is responsible for acid secretion. Potassium-competitive acid blocker (P-CAB), a new class of acid suppressant, inhibits gastric H⁺,K⁺-ATPase activity by reversible and K⁺-competitive binding to the enzyme whereas proton pump inhibitor (PPI) does by forming a covalent bond. In the pursuit of developing a novel P-CAB, a pyrrole derivative was found as a hit compound from high through-put screening (HTS), and its pharmacophore for potent inhibitory activity was identified. Following optimization by focusing on compounds with high ligand-lipophilicity efficiency (LLE) lead to discovery of Vonoprazan Fumarate (Takecab^®). This article describes the successful medicinal chemistry activity from a HTS hit compound to the launched drug that will give hope for the patients suffering from acid related diseases not only in Japan but in worldwide.

Circular polarized luminescence (CPL) is differential spontaneous emission based on left and right circularly polarized radiation. The luminescence has gained increased attention due to its application as secret light communication and 3D display. Recently, stimuli-responsive circular polarized luminescent systems have been reported. The systems comprise chiral luminescent molecules which change their structure responding external stimuli such as light and ions. This review focuses on the designs and properties of chemical- and photo-responsive circular polarized luminescent molecules.

Bacteria possess a cell wall based on a rigid extracellular matrix comprised of peptidoglycan (PG), which maintains their structural integrity. Although PG is a molecule that has attracted interest from various research fields, such studies have been limited by the difficulty to isolate the desired PG fragments. In order to make PG fragments available, many efforts have been made to achieve their synthesis. This review summarizes the synthetic strategies reported for the construction of PG fragments by the Fukase and Fujimoto’s group as well as the Mobashery’s group. Furthermore, applications of synthetic PG fragments in chemical biology are described.