Synthesis of phospholipids containing perfluorooctyl group and their interfacial properties

Highly fluorinated single-chained and/or double-chained phospholipids containing the perfluorooctyl group as the terminal segment of hydrophobic chains and a phosphocholine moiety as the hydrophilic headgroup were synthesized in order to investigate the effect of fluorinated segments on the stability of phospholipid monolayers formed at the air-water interface. Judging from the equilibrium spreading pressures (π_es) of their monolayers at the air-water interface, all of the fluorinated phospholipids formed more stable monolayers than the corresponding non-fluorinated counterparts. In addition, the fluorinated double-chained phosphatidylcholine containing C-C triple bond (monoyne group) formed stable and fluid vesicle membranes in water, although the single-chained phospholipids did not form vesicle membranes but micellar solutions under the present conditions.     

Structural elucidation of a methylenation reagent of esters: synthesis and reactivity of a dinuclear titanium(iii) methylene complex

Transmetallation of a zinc methylene complex [ZnI(tmeda)]₂(μ-CH₂) with a titanium(iii) chloride [TiCl₃(tmeda)(thf)] produced a titanium methylene complex. The X-ray diffraction study displayed a dinuclear methylene structure [TiCl(tmeda)]₂(μ-CH₂)(μ-Cl)₂. Treatment of an ester with the titanium methylene complex resulted in methylenation of the ester carbonyl to form a vinyl ether. The titanium methylene complex also reacted with a terminal olefin, resulting in olefin-metathesis and olefin-homologation. Cyclopropanation by methylene transfer from the titanium methylene proceeded by use of a 1,3-diene. The mechanistic study of the cyclopropanation reaction by the density functional theory calculations was also reported.

Transmetallation of a zinc methylene complex [ZnI(tmeda)]₂(μ-CH₂) with a titanium(iii) chloride [TiCl₃(tmeda)(thf)] produced a titanium methylene complex.     

Fabrication of mesoporous Pt nanotubes utilizing dual templates under a reduced pressure condition

Pt nanotubes with mesoporous walls have been successfully prepared for the first time by the combination of hard templates (porous anodic alumina membranes, PAAM) and soft templates (lyotropic liquid crystals, LLC).     

Chelation-assisted electrocyclic reactions of 3-alkenyl-2,2'-bipyridines: an efficient method for the synthesis of 5,6-dihydro-1,10-phenanthroline and 1,10-phenanthroline derivatives

An efficient method for the synthesis of substituted 5,6-dihydro-1,10-phenanthrolines and 1,10-phenanthrolines has been developed by means of the chelation-assisted photochemical electrocyclic reactions of 3-alkenyl-2,2'-bipyridines.     

Copper(I)-catalyzed carboxylation of aryl- and alkenylboronic esters

The copper(I)-catalyzed carboxylation reaction of aryl- and alkenylboronic esters proceeded smoothly under CO(2) to give the corresponding carboxylic acid in good yield. This reaction showed wide generality with higher functional group tolerance compared to the corresponding Rh(I)-catalyzed reaction.     

Practical and robust method for regio- and stereoselective preparation of (E)-ketene tert-butyl TMS acetals and beta-ketoester-derived tert-butyl (1Z,3E)-1,3-bis(TMS)dienol ethers

We developed an efficient, practical, robust method for the regio- and stereoselective preparation of (E)-ketene trimethylsilyl acetals (KSAs) derived from tert-butyl esters 1. The reaction was performed under convenient reaction conditions; LDA-TMSCl, 0-5 degrees C, and cyclopentyl methyl ether (CPME) solvent. Two kinds of (Z)- and (E)-KSAs derived from alpha-oxygen and alpha-nitrogen-substituted tert-butyl esters, respectively, were also obtained in good yield. The present protocol was successfully applied to a stereocontrolled preparation of useful, but highly reactive (less accessible) beta-ketoester-derived tert-butyl (1Z,3E)-1,3-bis(TMS)dienol ethers 2.     

Efficient control of pi-alkyne and vinylidene complex pathways for the W(CO)5(L)-catalyzed synthesis of two types of nitrogen-containing bicyclic compounds

When omega-acetylenic dienol silyl ethers containing NMs part in the tether were treated with a catalytic amount of W(CO)6 under photoirradiation, 2-azabicyclo[3.3.0]octanes were obtained in good yield via pi-alkyne complexes. On the other hand, treatment of the same substrates with a catalytic amount of W(CO)6 in the presence of n-Bu3N under the same reaction conditions gave 3-azabicyclo[3.3.0]octanes in good yield exclusively via vinylidene complexes. Thus, the pi-alkyne and vinylidene complex pathways are easily controlled by using a catalytic amount of W(CO)5(L) and an amine.     

Cell Spheroid Formation on the Surface of Multi-Block Copolymers Composed of Poly(2-methoxyethyl acrylate) and Polyethylene Glycol

3D structured cells have great drug screening potential because they mimic in vivo tissues better than 2D cultured cells. In this study, multi-block copolymers composed of poly(2-methoxyethyl acrylate) (PMEA) and polyethylene glycol (PEG) are developed as a new kind of biocompatible polymers. PEG imparts non-cell adhesion while PMEA acts as an anchoring segment to prepare the polymer coating surface. The multi-block copolymers show higher stability in water than PMEA. A specific micro-sized swelling structure composed of a PEG chain is observed in the multi-block copolymer film in water. A single NIH3T3-3-4 spheroid is formed in 3 h on the surface of the multi-block copolymers with 8.4 wt% PEG. However, at a PEG content of 0.7 wt%, spheroid formed after 4 days. The adenosine triphosphate (ATP) activity of cells and the internal necrotic state of the spheroid change depending on PEG loading in the multi-block copolymers. As the formation rate of cell spheroid on low-PEG-ratio multi-block copolymers is slow, internal necrosis of cell spheroid is less likely to occur. Consequently, the cell spheroid formation rate by changing the PEG chain content in multi-block copolymers is successfully controlled. These unique surfaces are suggested to be useful for 3D cell culture.     

Synthesis of two water-soluble polysaccharides by Acetobacter sp. NCI 1005

A new polysaccharide was isolated from the culture of Acetobacter aceti subsp. xylinum (A. xylinum) NCI 1005 grown on sucrose. The structure of the polymer was analyzed by nuclear magnetic resonance (NMR) spectroscopy. The water-soluble polysaccharide (WSP) was determined to be β(2, 6) linked polyfructan, which was structurally different from the polymer synthesized from glucose instead of sucrose by the same strain. The discovery of the new polysaccharide has elucidated that the bacterium has the ability to synthesize two different kinds of water-soluble polysaccharides.     

NMR Studies on the structure of cellulose. 2-dimensional solid state NMR approach

Two-dimensional C-H correlation NMR spectra are presented for the native cellulose types Iα and Iβ from Cladophora sp. A remarkable difference of correlation peaks between Iα and Iβ was observed, which indicates an essential structure difference between the two types of native cellulose.