Rapid enzymatic transglycosylation and oligosaccharide synthesis in a microchip reactor

Glycosidase-promoted hydrolysis was performed in a microreaction channel. The result was compared with the reaction in a micro-test tube. Transgalactosylation on p-nitrophenyl-2-acetamide-2-deoxy-beta-D-glucopyranoside was also examined in a microreaction channel, because transglycosylation is a useful method for oligosaccharide synthesis. We examined both the forward reaction, i.e., hydrolysis, and the reverse reaction, i.e., transglycosylation, in the microreaction channel. The results showed that both hydrolysis and transglycosylation were enhanced in the microreaction channel compared with the batch reaction.     

Ruthenium Complexes with Hydrophobic Ligands That Are Key Factors for the Optical Imaging of Physiological Hypoxia

The phosphorescence emission of ruthenium complexes was applied to the optical imaging of physiological hypoxia. We prepared three complexes with hydrophobic substituents on the phenanthroline ligand and characterized their emission, which was quenched by molecular oxygen. Among the complexes synthesized in this study, a pyrene chromophore‐linked ruthenium complex, Ru‐Py, exhibited optimal properties for the imaging of hypoxia; the prolonged lifetime of the triplet excited state of the ruthenium chromophore, which was induced by efficient energy distribution and transfer from the pyrene unit, provided the highest sensitivity towards molecular oxygen. The introduction of hydrophobic pyrene increased the lipophilicity of the complex, leading to enhanced cellular uptake. Consequently, the bright phosphorescence of Ru‐Py was seen in the cytoplasm of viable hypoxic cells, whereas the signal from aerobic cells was markedly weaker. Thus, we could clearly discriminate between hypoxic and aerobic cells by monitoring the phosphorescence emission. Furthermore, Ru‐Py was applied to optical imaging in live mice. An intramuscular injection of Ru‐Py successfully visualized ischemia‐based hypoxia, which was constructed by leg banding.     

The first total synthesis and reassignment of the relative stereochemistry of 16-hydroxy-16,22-dihydroapparicine

We report the first total synthesis and reassignment of the relative stereochemistry of naturally occurring 16-hydroxy-16,22-dihydroapparicine. Our novel route proceeds by a cascade reaction to efficiently construct a 1-azabicyclo[4.2.2]decane core, along with two stereocenters (C-15 and C-16). The C-16 quaternary carbon was constructed through stereospecific 1,2-addition using an indole nucleophile to an aldehyde or a methylketone. The stereospecific synthesis of two diastereomers of the target product has revealed the true relative stereochemistry of the natural compound.     

Tetracyanoethylene oxide not only oxidizes sulfides to sulfoxides but also reduces sulfoxides to sulfides

It was found that tetracyanoethylene oxide not only oxidizes sulfides to sulfoxides but also reduces sulfoxides to sulfides with generation of two molecules of carbonyl cyanide. The reaction thus also functions as a new method for generation of carbonyl cyanide.     

Ag(+)-inserted NbO(2)F as a Novel Photocatalyst

The insertion of Ag(+) into NbO(2)F narrowed the band gap from 3.2 eV (NbO(2)F) to 3.0 eV (Ag-NbO(2)F), which shifted the light absorption edge from the UV light region to the near-violet light region. The photocatalytic activities of NbO(2)F and Ag-NbO(2)F were evaluated by the decomposition of gaseous 2-propanol (IPA) under 400-530 and 300-400 nm light irradiations. Ag-NbO(2)F could decompose IPA to CO(2) via acetone under both irradiation conditions. The value of the quantum efficiency was of the same order under both 400-530 and 300-400 nm light irradiations, which suggested the complete hybridization of the Ag4d and O2p orbitals in the valence band of Ag-NbO(2)F resulted in the 400-530 nm light sensitivity. The density of states calculations also supported the complete mixing of Ag4d and O2p.