Efficient and stereoselective synthesis of the disaccharide fragment of incednine

Efficient and stereoselective synthesis of a disaccharide fragment, 2-deoxy-4-O-(N'-monodemethyl-D-forosaminyl)-2-methylamino-β-D-xylopyranoside, of a novel antibiotic, incednine (1), is described. The key β-stereoselective formation of a 2,3,4,6-tetradeoxy-4-methylamino glycoside bond was achieved by remote participation-assisted glycosylation.     

The room-temperature synthesis of anisotropic CdHgTe quantum dot alloys: a "molecular welding" effect

The room-temperature chemical transformation of spherical CdTe nanoparticles into anisotropic alloyed CdHgTe particles using mercury bromide in a toluene/methanol system at room temperature has been investigated. The resulting materials readily dissolved in toluene and exhibited a significant red-shift in the optical properties toward the infrared region. Structural transformations were observed, with electron microscopy showing that the CdTe nanoparticles were chemically attached ('welded') to other CdTe nanoparticles, creating highly complex anisotropic heterostructures which also incorporated mercury.     

Expanded porphyrins and aromaticity

meso-Aryl-substituted expanded porphyrins that are porphyrin homologues consisting of more than five pyrrolic units are a nice platform to realize diverse aromatic and antiaromatic species as well as stable radical species. They are also an ideal series to realize topologically twisted molecules with distinct M?bius aromaticity and antiaromaticity.     

Application of olefin metathesis to organic synthesis. Syntheses of civetone and macrolides

Diethyl 9-octadecene-1,18-dioate was obtained in 87% yield based on 50% theoretical conversion by the olefin metathesis reaction catalyzed by WOCl₄-Cp₂TiMe₂. The Dieckmann condensation of this diester using potassium hydride afforded 2-ethoxycarbonylcyclo-9-heptadecenone, which was converted by hydrolysis and decarboxylation to cyclo-9-heptadecenone (civetone) as a mixture of cis and trans isomers (1.3 : 1) in 54% yield. Also 9-octadecen-18-olide was obtained in 17.9% by the metathesis of oleyl oleate.     

Structure of amipurimycin,a nucleoside antibiotic having a novel branched sugar moiety

Structure of amipurimycin was determined chemically to be $\text{1}$.     

Circumventing air bubbles in microfluidic systems and quantitative continuous-flow PCR applications

Polymerase chain reaction (PCR) is an essential part of research based on genomics or cell analysis. The development of a microfluidic device that would be suitable for high-temperature-based reactions therefore becomes an important contribution towards the integration of micro-total analysis systems (μTAS). However, problems associated with the generation of air bubbles in the microchannels before the introduction of the assay liquid, which we call the “initial start-up” in this study, made the flow irregular and unstable. In this report, we have tried to address these problems by adapting a novel liquid-flow method for high-temperature-based reactions. A PDMS-based microfluidic device was fabricated by soft-lithography techniques and placed on a cartridge heater. The generation of the air bubbles was prevented by introducing the fluorinated oil, an inert and highly viscous liquid, as the cap just before the introduction of the sample solutions into the microchannels. The technique was applied for continuous-flow PCR, which could perform PCR on-chip in a microfluidic system. For the evaluation of practical accuracy, plasmid DNA that serves as a reference molecule for the quantification of genetically modified (GM) maize was used as the template DNA for continuous-flow PCR. After PCR, the products were collected in a vial and analyzed by gel electrophoresis to confirm the accuracy of the results. Additionally, quantitative continuous-flow PCR was performed using TaqMan technology on our PCR device. A laser detection system was also used for the quantitative PCR method. We observed a linear relationship between the threshold cycle (Ct) and the initial DNA concentration. These results showed that it would be possible to quantify the initial copies of the template DNA on our microfluidic device. Accurate quantitative DNA analysis in microfluidic systems is required for the integration of PCR with μTAS, thus we anticipate that our device would have promising potential for applications in a wide range of research.