Location of the metal atoms in Ce2@C78 and its bis-silylated derivative

Dimetallofullerene Ce(2)@C(78) and its bis-silylated derivative (1) were successfully prepared and fully characterized.     

Photocyclization reaction of a diarylmaleimide derivative in polar solvents

Photochromism of a symmetric diarylmaleimide derivative, having two thiophene rings (1), and a non-symmetric derivative having a S,S-dioxide thiophene ring and a thiophene ring (2) as the aryl moieties, was studied in various solvents. The photocyclization quantum yield of gradually decreased with increasing the solvent polarity and the reaction was not observed in polar solvents, such as ethanol and acetonitrile; on the other hand, such a strong solvent dependence of the photocyclization reaction was not observed for ; the different behavior is attributed to the weaker electron donating ability of the S,S-dioxide thiophene ring.     

An efficient heteropolyacid catalyzed acylation of pyruvate esters to alpha-acyloxyacrylate esters as potential candidate monomers for bio-based polymers

Alpha-acyloxyacrylate esters were efficiently synthesized from pyruvate esters and carboxylic anhydrides under mild conditions. These esters are potential candidate monomers for bio-based polymers with high durability and transparency. Tungsten-based Keggin type heteropolyacids, especially H(3)PW(12)O(40), worked more effectively as catalysts for this reaction than other typical acids.     

Internal amide-triggered cycloaromatization of maduropeptin-like nine-membered enediyne

In the Masamune-Bergman cyclization of a nine-membered non-conjugated enediyne with an internal, maduropeptin-like nucleophile, the exocyclic alkene migrated to form the nine-membered conjugated enediyne, triggered by the intramolecular addition of the amide group; final aromatized products showed up to 85% yield.     

Plant pathogen recognition as a natural, original and simple model for chemogenomics: a brief overview of cell-based assays to screen for peptides acting as plant defense activators

As plants lack a circulatory system and adaptive immune system, they have evolved their own defense systems distinct from animals, in which each plant cell is capable of defending itself from pathogens. Plants induce a number of defense responses, which are triggered by a variety of molecules derived from pathogenic microorganisms, referred to as microbe-associated molecular patterns (MAMPs), including peptides, proteins, lipopolysaccharide, beta-glucan, chitin, and ergosterol. The interaction between plants and chemicals in the context of plant defense represents a "natural" and simple model for chemogenomics, at the intersection between chemical and biological diversities. For protection of crop plants from diseases, it has been shown to be effective to stimulate the plant immunity by chemical compounds, the so-called "plant defense activators". Combinatorial chemistry techniques can be applied to the search for novel plant defense activators, but it is essential to establish an efficient and reliable screening system suitable for library screening. For studies of the plant immune system, it is difficult to use isolated proteins as biological targets because the receptors for MAMP recognition are largely unknown and even the receptors identified so far are transmembrane proteins. Therefore, screening for novel peptides acting on MAMP receptors from combinatorial libraries must rely on a solution-phase assay using cells as the biological targets. In this review, we introduce the cell-based lawn format assay for identification of peptides acting as plant defense activators from combinatorial peptide libraries. The requirements and limitations in constructing the screening system using combinatorial libraries in the studies of plant sciences are also discussed.     

Rhodium‐Catalyzed Oxidative Coupling between Salicylaldehydes and Internal Alkynes with C?H Bond Cleavage To Produce 2,3‐Disubstituted Chromones

A direct oxidative coupling of salicylaldehydes with internal alkynes proceeds efficiently with cleavage of the aldehyde C? H bond to produce the corresponding chromone derivatives. A rhodium catalyst in combination with a cyclopentadiene ligand and a copper oxidant promote this straightforward annulation reaction. Solid‐state luminescence was observed for certain chromone products.     

Control of the photoreactivity of diarylethene derivatives by quaternarization of the pyridylethynyl group

Photochromic behavior of diarylethene derivatives with (4-pyridyl)ethynyl group directly attached to the 6-pi hexatriene moieties of the diarylethenes was investigated. Upon quaternarization of the pyridine moieties, the photoreactivity was strongly suppressed. On the other hand, diarylethene derivatives with nonconjugated (4-pyridyl)ethyl group exhibited the photochromic reactivity, regardless of whether pyridyl rings are quaternarized or not. In the case of the (4-pyridyl)ethynyl-substituted compounds, the photochromic reactivity was suppressed by the addition of trifluoroacetic acid and was restored by diethylamine.