One-pot synthesis of 2,3-disubstituted benzofurans from 2-chlorophenols using palladium–dihydroxyterphenylphosphine catalyst

2,3-Disubstituted benzofurans possessing 2-hydroxyphenyl moiety at the C-3 position were synthesized from readily available 2-chlorophenols and terminal alkynes by hydroxy-directed ortho-Sonogashira coupling and subsequent oxypalladation/reductive elimination, using Pd-dihydroxyterphenylphosphine catalyst. The catalyst accelerates not only the Sonogashira coupling but also the introduction of 2-hydroxyphenyl group at the C-3 position of benzofuran.     

Photoluminescent and Liquid‐Crystalline Properties of Donor–Acceptor‐Type 2,5‐Diarylthiazoles

The synthesis of donor–acceptor‐type 2,5‐diarylthiazoles that bear electron‐donating N,N‐dialkylamine and electron‐withdrawing cyano groups at the 2‐ and 5‐position, respectively, were carried out with transition‐metal‐catalyzed C? H arylation reactions developed by us. The compounds were synthesized by the C? H arylation of unsubstituted thiazole at the 2‐position with a palladium/copper catalyst in the presence of tetrabutylammonium fluoride (TBAF) as an activator. Further C? H arylation of the 2‐arylated thiazole at the 5‐position was carried out by the palladium‐catalyzed reaction in the presence of silver(I) fluoride to afford the donor–acceptor‐type 2,5‐diarylthiazoles with N,N‐dialkylamine groups of different chain lengths. The UV/Vis absorption, photoluminescence, and electrochemical behavior were similar regardless of chain length, whereas liquid‐crystalline behavior and thermal characteristics were found to be dependent on the alkyl‐chain length. The compounds with N,N‐diethylamine or N‐butyl‐N‐methyl groups showed a stable liquid‐crystalline phase over a wide temperature range as well as higher stability to thermal decomposition.     

Palladium-catalyzed C-H homocoupling of thiophenes: facile construction of bithiophene structure

Palladium-catalyzed C-H homocoupling of thiophene derivatives takes place in the presence of silver(I) fluoride or acetate. A variety of bithiophenes are obtained in good to excellent yields. In particular, the reaction of 2-bromothiophene proceeds at room temperature to afford 5,5'-dibromo-2,2'-bithiophene, where the bromine atom is completely intact in the palladium-catalyzed reaction. XRD analysis reveals that silver fluoride is reduced to silver(0) during the reaction.     

Convenient synthesis of α-amino amides using low-valent tantalum prepared from TaCl5 and Zn

We have developed a general preparation method of α-amino amides from imines and isocyanates using low-valent tantalum prepared from TaCl₅ and Zn in situ. This method was successfully applied to various imines derived from benzaldehyde derivatives with electron-withdrawing or electron-donating substituents, heteroaromatic aldehydes, and an aliphatic, α-branched aldehyde, giving the corresponding α-amino amides in high yields.     

N,N,N',N'-Tetrakis(2-quinolylmethyl)-2-hydroxy-1,3-propanediamine (Htqhpn) as a supporting ligand for a low-valent (mu-O)2 tetranuclear manganese core

A new heptadentate N6-O1 ligand, N,N,N',N'-tetrakis(2-quinolylmethyl)-2-hydroxy-1,3-propanediamine (Htqhpn), was synthesized and used to generate compounds with linearly ordered MnIIMnIIIMnIIIMnII tetranuclear cores. This is the lowest valent tetranuclear manganese complex that exhibits a (mu2-O)2Mn2 core in the molecule. The electron paramagnetic resonance and magnetic measurements of these tetranuclear complexes suggest moderately strong antiferromagnetic coupling for the central MnIII2 core, with weak coupling between the MnII and MnIII centers.     

Fusarielin A as an anti-angiogenic and anti-proliferative agent: basic biological characterization

Fusarielin A shows anti-angiogenic activity in the human umbilical vein endothelial cell (HUVEC) tube formation assay. Structural development studies indicated the importance of the hydroxyl groups in this molecule. A 3H-labeled derivative and a fluorescent affinity-labeling agent were prepared and used to examine the cellular distribution and biological behavior of fusarielin A.     

Protein extraction for 2-DE from the lamina of Ecklonia kurome (laminariales): recalcitrant tissue containing high levels of viscous polysaccharides

Extraction of proteins from the tissues of laminarialean algae, i.e. kelp, is difficult due to high levels of nonprotein interfering compounds, mainly viscous polysaccharides. To establish proteomic analysis of kelp species, an ethanol/phenol extraction method was developed and compared to other popular methods. Proteins were extracted with phenol from crude protein powder, obtained by homogenizing the kelp tissues in ice-cold ethanol. The ethanol/phenol method produced high-quality proteins of the highest purity from the lamina of Ecklonia kurome, one of the Japanese dominant laminarialean algae. This method gave well-resolved 1-D SDS-PAGE or 2-DE images with low background and the highest number of bands or spots. In particular, proteins with neutral to basic pI's were efficiently extracted. Furthermore, 27 spots on the 2-DE gel were extensively identified by MALDI-TOF/TOF analysis. To the best of our knowledge, this is the first report of a protocol for protein extraction from kelp tissues that gives satisfactory 2-D protein profiles. It is expected that the protocol can be applied to other algae tissues or other recalcitrant plant tissues containing high levels of nonprotein interfering compounds.     

Ferroelectric Ionic Molecular Crystals with Significant Plasticity and a Low Melting Point: High Performance in Hot-Pressed Polycrystalline Plates and Melt-Grown Crystalline Sheets

Among ferroelectric crystals based on small molecules, plastic/ferroelectric crystals are currently receiving particular attention because they can be used as bulk polycrystals. Herein, we show that an ionic molecular ferroelectric crystal, guanidinium tetrafluoroborate, exhibits significant malleability and multiaxial ferroelectricity despite the absence of a plastic crystal phase. Powder samples of this crystal can be processed into transparent bulk crystalline plates either by press-forming or by melt-growing. The plates show high ferroelectric performance and related properties, demonstrating the largest hitherto reported spontaneous polarization for bulk polycrystals of small-molecule-based ferroelectrics. Owing to the ready availability of large-scale materials and processability into various bulk crystalline forms, this ferroelectric crystal represents a highly promising functional material that will boost research on diverse applications as bulk crystals.     

A novel fabrication technique and new conjugated polymers for multilayer polymer light-emitting diodes

We report a novel fabrication technique for multilayer light-emitting diodes composed of new polyoxadiazole, POD, conjugated polymers for the first time. The fabrication technique called vapor deposition polymerization is described. Chemical modification of monomers brought about the enhancement of reactivity and the production of high molecular weight of POD. Emission color with photoexcitation was controllable from violet-blue to green by varying the chemical structures of PODs. It was found that PODs could be employed as either electroluminescent or carrier-injecting layers by the optimization of the device structure. Two types of bilayer devices, which are constructed with POD/tris (8-quinolinoato) aluminum, Alq₃, and with two POD layers with different chemical structures, were investigated. Carrier injection begins in the POD/Alq₃ bilayer device near 7 V, and the device emitted green light from Alq₃. The maximum luminance of the POD/Alq₃ device reached 3500 cd/m². The POD/POD bilayer device emitted blue light with maximum luminance of 21 cd/m². Electroluminescence spectra of the devices coincided with photoluminescence spectra of each emitting material used. © 1997 John Wiley & Sons, Ltd.     

Catalytic asymmetric synthesis of stereoisomers of 1-C-n-butyl-LABs for the SAR study of α-glucosidase inhibition

We achieved synthesis of seven stereoisomers of 1-C-n-butyl-L-iminofuranose derivatives using catalytic asymmetric alkylation and Negishi coupling as key reactions. The synthetic strategy based on these key reactions was quite useful, since both α- and β-iminofuranoses could be obtained by switching the chirality of the ligand employed for the AAA reaction. The common intermediates for α- and β-isomers were subjected to further manipulations to install a diol unit at C2 and C3 to give the desired stereoisomers of L-iminofuranose derivatives. We achieved the preparation of all stereoisomers of 1-C-n-butyl-L-iminofuranose derivatives, with the exception of β-lyxo type iminofuranose. It is noteworthy that a synthetic route for many stereoisomers of iminofuranose derivatives was developed. Unfortunately, none of the L-iminofuranoses obtained showed inhibitory activity against the α-glycosidases examined—e.g., maltase, sucrase, and isomaltase.