Cross‐Coupling of Organolithium with Ethers or Aryl Ammonium Salts by C−O or C−N Bond Cleavage

Various aryl‐, alkenyl‐, and/or alkyllithium species reacted smoothly with aryl and/or benzyl ethers with cleavage of the inert C?O bond to afford cross‐coupled products, catalyzed by commercially available [Ni(cod)₂] (cod=1,5‐cyclooctadiene) catalysts with N‐heterocyclic carbene (NHC) ligands. Furthermore, the coupling reaction between the aryllithium compounds and aryl ammonium salts proceeded under mild conditions with C?N bond cleavage in the presence of a [Pd(PPh₃)₂Cl₂] catalyst. These methods enable selective sequential functionalizations of arenes having both C?N and C?O bonds in one pot.     

Application of DEM modified with enlarged particle model to simulation of bead motion in a bead mill

We applied the discrete element method （DEM） of simulation modified by an enlarged particle model to simulate bead motion in a large bead mill. The stainless-steel bead mill has inner diameter of 102 mm and mill length of 198 mm. The bead diameter and filling ratio were fixed respectively at 0.5 mm and 85%. The agitator rotational speed was changed from 1863 to 3261 rpm. The bead motion was monitored experimentally using a high-speed video camera through a transparent mill body. For the simulation, enlarged particle sizes were set as 3-6 mm in diameter. With the DEM modified by the enlarged particle model, the motion of enlarged particles in a mill was simulated.The velocity data of the simulated enlarged particles were compared with those obtained in the experiment. The simulated velocity of the enlarged particles depends on the virtual frictional coefficient in the DEM model. The optimized value of the virtual frictional coefficient can be determined by considering the accumulated mean value. Results show that the velocity of the enlarged particles simulated increases with an increase in the optimum virtual frictional coefficient, but the simulated velocity agrees well with that determined experimentally by optimizing the virtual frictional coefficient in the simulation. The computing time in the simulation decreases with increased particle size.     

Efficient synthesis of an optically active tetrahydrozerumbone exhibiting a fragrance and the application of zerumbone derivatives with a medium ring structure

(R)-Tetrahydrozerumbone 2, which has a powerful balmy fragrance, contains a stereogenic carbon at the C2 position and can be easily prepared from zerumbone 1, one of the most important materials displaying an NMRDOS character. The reduction of 2 gave two diastereomers of tetrahydrozerumbol 3, and the optically active (>99%ee) alcohols were obtained by a lipase-catalyzed stereoselective transesterification of each racemic alcohol. A barrier to this development is a long reaction time (about four weeks) and the need to separate the diastereoisomers. The desired (2R)-form of 3 was efficiently obtained by a lipase-catalyzed transesterification under optimized conditions using a diastereomeric mixture of racemic 3 as the starting material without separation of the diastereomers. Using this method, the reaction of other zerumbone derivatives is greatly improved.     

Defect-effects on the photoluminescence of ZrO2 bulk,film and nanocrystals

The photoluminescence (PL) properties of ZrO₂ have been measured at different temperatures between 7 and 300 K, using various kinds of ZrO₂ specimens: bulk crystal melt-grown by a large solar furnace, thermally oxidized zirconium plate (ZrO₂ film crystal on Zr ) and nanocrystals (surface area: 35–45m²/g, diameter: 20–30 nm). The results clarify the deep and shallow energy level structures in the energy gap. Reversible UV-laser-light-induced spectral changes are observed for all of the specimens in different specimen-atmospheres (vacuum and O₂ gas). The results elucidate the defect-effects of the PL properties and the PL enhancement mechanism in ZrO₂ nanocrystals.     

Efficiently Synthesizing Lacto-Ganglio-Series Gangliosides by Using a Glucosyl Ceramide Cassette Approach: The Total Synthesis of Ganglioside X2

The first total synthesis of the hybrid ganglioside X2, which consisted of a highly branched octasaccharide and ceramide moieties, was accomplished by using a glucosyl ceramide cassette approach. With a disaccharyl donor, the heptasaccharide could not be constructed by glycosylation of the C4 hydroxy group of galactose at the reducing end of the pentasaccharide. In contrast, through an alternative approach with two branched glycan units, a GM2-core trisaccharide, and a lacto-ganglio tetrasaccharide, the heptasaccharyl donor could be prepared and subsequently joined with a glucosyl ceramide cassette to afford the protected ganglioside, X2. Finally, global deprotection completed the synthesis, thus affording the pure ganglioside X2.