Preparation of 2-, 3-, 4- and 7-(2-alkylcarbamoyl-1-alkylvinyl)benzo[b]furans and their BLT1 and/or BLT2 inhibitory activities

Several 2-alkylcarbamoyl-1-alkylvinylbenzo[b]furans were designed to find a selective leukotriene B4 (LTB4) receptor antagonist. 2-(2-Alkylcarbamoyl-1-alkylvinyl)benzo[b]furans having a substituent group at the 3-position, 4-(2-alkylcarbamoyl-1-methylvinyl)benzo[b]furans having a substituent group at the 3-position, and 7-(2-alkylcarbamoyl-1-methylvinyl)benzo[b]furans and 3-(2-alkylcarbamoyl-1-alkylvinyl)benzo[b]furans were prepared and evaluated for LTB4 receptor (BLT1 and BLT2) inhibitory activities. (E)-3-Amino-4-[2-[2-(3,4-dimethoxyphenyl)ethylcarbamoyl]-1-methylvinyl]benzo[b]furan ((E)-17c) showed potent and selective inhibitory activity for BLT2. On the other hand, (E)-7-(2-diethylcarbamoyl-1-methylvinyl)benzo[b]furan ((E)-27a) showed potent inhibitory activity for both BLT1 and BLT2.     

Molecular rectification of a helical peptide with a redox group in the metal-molecule-metal junction

A helical hexadecapeptide immobilized on gold via a thiophenyl group at the N-terminal was analyzed by scanning tunneling microscopy under ultrahigh vacuum to obtain the I-V response at a molecular level. The attenuation factor of the electron transfer through the hexadecapeptide was determined by applying the Simons model to the I-V response to show better molecular conductance of the hexadecapeptide than dodecanethiol. Chemical modification at the C-terminal of the hexadecapeptide with a ferrocene unit, on the other hand, brought about significant changes in the I-V response, where the helical peptide became more conductive at the negative bias voltage. The molecular rectification behavior is due to the ferrocene unit regulating the direction of the electron transfer at the metal-molecule junction.     

Furopyridines. xvi. Photo[2+2]cycloaddition of furo-[3,2-c]pyridin-4(5H)-one with acrylonitrile

The photocycloaddition of furo[3,2-c]pyridin-4(5H)-one (1) and its N-methyl derivative (1-Me) to acrylonitrile has been studied. The structures of the photoadducts isolated by column chromatography were determined on the basis of the nuclear magnetic resonance spectroscopy. The cycloaddition of 1 afforded an adduct 2 at the carbonyl oxygen and four possible isomers 3a, 3b, 3c and 3d of cyclobutane-fused adduct at the 6- and 7-position of 1 , and the addition of 1-Me the N-methyl derivatives 3a-Me, 3b-Me, 3c-Me and 3d-Me.     

Furopyridines. XXV. Synthesis of 5-substituted furo [2,3-b]pyridines

Derivatives ( 2–8 ) of furo[2,3-b]pyridine having a substituent at the β-position to the ring nitrogen were prepared from the 5-nitro compound 1 via the Sandmeyer reaction.     

Efficient photocurrent generation by self-assembled monolayers composed of 3 10-helical peptides carrying linearly spaced naphthyl groups at the side chains

Self-assembled monolayers (SAMs) were prepared on a gold substrate from a 310-helical peptide carrying three naphthyl groups at the side chain (SSN3B) or from the reference peptides carrying no or one naphthyl group. The 310-helical conformation of SSN3B in solution was confirmed by 1H NMR spectroscopy and geometry optimization. Cyclic voltammetry and infrared absorption-reflection spectroscopy showed vertical molecular orientation and a well-packed structure in the SSN3B SAM. Anodic photocurrent was successfully generated by the SSN3B SAM in the presence of triethanolamine, and the current intensity was found to be much larger than those by the other SAMs from peptides carrying one naphthyl group. It was therefore concluded that the linearly spaced naphthyl groups along the helical axis act as photosensitizer and electron-hopping site to promote photocurrent generation remarkably.     

New strontium polysulfides, SrS3, and Sr2(OH)2S4.10H2O, obtained by the high-pressure treatment of a Sr-S mixture

A new polymorph of SrS(3) was obtained by a reaction of SrS and S with an atomic ratio of Sr:S = 1:5 under a pressure of 5 GPa at 1200 degrees C. It crystallized in a tetragonal unit cell with a = 6.708(1) A, c = 3.942(1) A, and V = 177.36(6) A(3). It was isotypic with BaS(3), and contained S3(2-) polysulfide ions. The product obtained from the high-pressure synthesis contained an amorphous component. It was highly deliquescent and formed a yellowish solution. A new layered polysulfide, Sr(2)(OH)(2)S(4).10H(2)O, crystallized in the solution. The sulfide belonged to a triclinic space group of P (No. 2) with lattice constants of a = 5.9107(5) A, b = 7.8682(6) A, c = 9.4134(6) A, alpha = 75.639(6) degrees, beta = 73.824(3) degrees, gamma = 71.639(3) degrees, V = 392.83(5) A(3), and Z = 1. Each Sr ion was coordinated with one OH ligand and eight H(2)O ligands. Six H(2)O ligands out of the eight were bridging ligands to form two-dimensional [Sr(2)(OH)(2)(H(2)O)(10)(2+)]( infinity ) cationic layers, between which S4(2-) tetrapolysulfide ions were situated. The S4(2-) anion had a coplanar configuration with a dihedral angle of 180.0 degrees. The stability of S4(2-) anions having different conformations was discussed from a viewpoint of ab initio MO calculations on changing the dihedral angles of S4(2-).     

A novel polypseudorotaxane composed of cyclic beta-peptide as bead component

A polypseudorotaxane composed of cyclic hexamers of beta-glucosamino acid and poly(ethylene glycol) (PEG) was constructed, where the beads were stacked unidirectionally together via hydrogen bonds to form a peptide nanotube.     

N-Homoclinic bifurcations for homoclinic orbits changing their twisting

We study bifurcations, calledN-homoclinic bifurcations, which produce homoclinic orbits roundingN times (N2) in some tubular neighborhood of original homoclinic orbit. A family of vector fields undergoes such a bifurcation when it is a perturbation of a vector field with a homoclinic orbit.N-Homoclinic bifurcations are divided into two cases; one is that the linearization at the equilibrium has only real principal eigenvalues, and the other is that it has complex principal eigenvalues. We treat the former case, espcially that linearization has only one unstable eigenvalue. As main tools we use a topological method, namely, Conley index theory, which enables us to treat more degenerate cases than those studied by analytical methods.     

Novel nucleophilic C?C bond‐forming tele‐reaction of imidazole ring

Reaction of 2‐(1‐chloro‐2,2‐dimethylpropyl)‐1‐methyl‐1H‐irnidazoles with diethyl methylmalonate in the presence of NaH gave a normal S_N product, 2‐[(1,1‐diethoxycarbonylethyl)‐2,2‐dimethylpropyl]‐1‐methyl‐1H‐imidazole (2a) , and two tele‐reaction products, 5‐(1,1‐diethoxycarbonylethyl)‐1‐methyl‐2‐(2,2‐dimethylpropyl)‐1H‐imidazole (3a) and trans‐4,5‐di‐(1,1‐diethoxycarbonylethyl)‐4,5‐dihydro‐1‐methyl‐2‐(2,2‐dimethylpropyl)‐1H‐imidazole (4a) in 5, 17 and 70% yields, respectively. The scope and mechanism of this reaction are discussed.