Condensation products of 2-bromo-3-substituted-inden-1-ones with several primary amines

2-Bromo-3-substituted-inden-1-ones 2 reacted with L-cysteine or 2-aminobenzenethiol to produce 2,3-dihydro-5-phenylindeno[2,1-b][1,4]thiazine in moderate yield or 6-substituted-indeno[2,1-b][1,4]benzothiazines in good yield. The debrominated oxime and the phenylhydrazone of 2 were separated into their respective E- and Z-conformers by column chromatography and their E- and Z-configurations were obtained from the ¹H nmr spectra.     

Double 1,3-dipolar cycloadditions of meso-ionic heterocycles with N-phenylmaleimide

3-Phenylsydnone and 2,4-diphenyl-3-methyloxazolium 5-oxide undergo double 1,3-dipolar cycloadditions with two molecules of N-phenylmaleimide to produce 4,8-iminobenzo[1,2-c:4,5-c′]dipyrrole-1,3,5,7-tetrone derivatives in a stereoselective manner.     

Lignans and sesquiterpenes from Magnolia praecocissima

A new lignan 1 was isolated together with the five known lignans 2-6 and four sesquiterpenes 7-10 from the seeds of Magnolia praecocissima. The structure of 1 was elucidated by analysis of spectroscopic data and chemical reaction. Furthermore, the absolute configurations of 1, 2, and 3 were determined by the modified Mosher's method.     

Synthesis of 2H-indazole-4,7-dione derivatives from 3-phenylsydnone and p-toluquinone. The crystal and molecular structure of 6-bromo-5-methyl-2-phenyl-2H-indazole-4,7-dione

The 1,3-dipolar cycloaddition of 3-phenylsydnone with p-toluquinone afforded 5-methyl- and 6-methyl-2-phenyl-2H-indazole-4,7-diones 3a and 3b. No regioselectivity was observed in this cycloaddition yielding an equimolar amount of the regioisomers. Reactions of 3a and 3b with bromine gave the corresponding mono- 4a and 4b and dibromo derivatives 5a and 5b , respectively. The crystal structure of 6-bromo-5-methyl-2-phenyl-2H-indazole-4,7-dione ( 4a ) has been determined by the single crystal X-ray method. The crystals are monoclinic, space group PI with two molecules in a unit cell of dimensions a = 8.029(1), b = 14.309(1), c = 5.895(1)Å, β = 90.24(1)° and V = 621 ų. The structure has been solved by the direct method using 1827 reflections and refined by full-matrix least-squares calculations to R = 0.0739.     

Radical cyclization in heterocycle synthesis 15. Relationship between a Radical species and radical acceptors of three different types of double bond in radical addition-cyclization

Relationship between a radical species and radical acceptors of three different types of double bond in radical addition-cyclization was systematically investigated. Substrates carrying alpha,beta-unsaturated amide, isolated olefin, and oxime ether moieties underwent radical addition-cyclization to give differently substituted lactams depending upon the radicals used. The sulfanyl radical addition-cyclization of the substrate proceeded smoothly to give the 5-membered lactam having an alkoxyamino group as a result of preferable addition of an intermediary alpha-carbonyl radical to the oxime ether. On the other hand, the triethylborane-mediated radical addition-cyclization gave the lactam bearing an iodomethyl group as a result of addition to an intermediary alpha-carbonyl radical to isolated olefin. The different regioselectivity was explained by the stability of the intermediary radical and the interaction between SOMO and HOMO.     

Determination of histamine and some other amines by high-performance capillary electrophoresis with on-line mode in-capillary derivatization

We have developed a method for the determination of histamine (His), tyramine (Tyr) and cadaverine (Cad) using high-performance capillary electrophoresis with fluorescence detection and an on-line mode in-capillary derivatization with o-phthalaldehyde (OPA)/N-acetylcysteine (NAC) as derivatization reagent. HPCE separation of His, Tyr, Cad and Spermidine (Spd) was influenced by sodium dodecyl sulfate (SDS) and phosphate–borate buffer (pH 10) concentration. After optimization of the method, a 4-component amine solution containing His, Tyr, Cad and Spd could be separated and detected by using 2 mM OPA/NAC–20 mM SDS–20 mM phosphate–borate buffer (pH 10) as a run buffer at an applied voltage of 25 kV, with detection at 340 nm. Although a practical sensitivity level can be obtained by using fluorescence detection (λ_ex=340 nm, λ_em=450 nm) instead of ultraviolet–visible detection, Spd was not detected at all. The precision (relative standard deviation; n=15) of this method for within- and between-days is less than 2.9% (peak area) and 1.3% (migration time), respectively. Linearity for these analytes, except for Spd, was established over a concentration range of 0.02 to 1.00 μmol/ml and detection limits (S/N=3) range from 1 nmol/ml for His and Tyr to 5 nmol/ml for Cad. The determination of His and some amines in aging raw fish meat samples (room temperature, 48 h) was carried out using the described method with fluorescence detection.     

Unique adsorption behavior of H2 and CO over group 8-10 metals encapsulated inside silica nanotubes and nanocapsules

Various silica nanotubes and nanocapsules have been prepared successfully, possessing unique silica walls of selective H2 permeation and encapsulate group 8-10 metal particles inside and exhibit a marked stabilization effect of H2 and CO over the metals in the network of silica wall and inside nanoscale cavities.     

A true electron-transfer reaction between 5,10,15,20-tetraphenylporphyrinato cadmium(II) and the hexacyanoferrate couple at the nitrobenzene/water interface.

The ability of some metal complexes of 5,10,15,20-tetraphenylporphyrin (TPP) to give a voltammetric wave due to the heterogeneous electron transfer (ET) at a nitrobenzene (NB)/water (W) interface has been examined. The previously-proposed, electron-conductor separating oil-water (ECSOW) system has been successfully employed to find that the TPP complex with cadmium(II) added to NB gives a well-defined, reversible wave for the heterogeneous (i.e., "true") ET with the hexacyanoferrate couple in W. A digital simulation analysis has entirely excluded the possibility of the ion-transfer mechanism due to the homogeneous ET in W. The a.c. impedance method has then been used to determine the kinetic parameters including the standard rate constant k0 (= 0.10 cm M(-1) s(-1)) and the transfer coefficient alpha (= 0.53 at the half-wave potential). These values are in good agreement with those predicted from the Marcus theory with the assumption that the heterogeneous ET due to molecular collision occurs at the "sharp" NB/W interface.     

Facile construction of sulfanyl-terminated poly(ethylene glycol)-brushed layer on a gold surface for protein immobilization by the combined use of sulfanyl-ended telechelic and semitelechelic poly(ethylene glycol)s

A sulfanyl-terminated poly(ethylene glycol) (PEG)-brushed layer was constructed on a gold sensor platform by consecutive treatment with a sulfanyl-ended semitelechelic PEG (2 kDa, hereafter "MeO-PEG-SH (2k)") and a sulfanyl-ended telechelic PEG (5 kDa, hereafter "SH-PEG-SH (5k)"). Our strategy of constructing the sulfanyl-terminated PEG-brushed gold surface is based on mixed-PEG-brush formation from the longer SH-PEG-SH (5k) and the shorter MeO-PEG-SH (2k), where the preimmobilized shorter MeO-PEG-SH (2k) prevents loop formation in the longer SH-PEG-SH (5k) on the surface and the free sulfanyl group at one end of the longer SH-PEG-SH is exposed to the mixed-PEG tethered-chain surface. From the experimental results obtained from surface plasmon resonance analysis, it became apparent that the immobilization density and the orientation of the longer SH-PEG-SH (5k) on the gold surface could be controlled by the amount of preimmobilized shorter MeO-PEG-SH (2k). Under the optimized conditions of MeO-PEG-SH (2k) premodification, the constructed MeO-PEG-SH (2k)/SH-PEG-SH (5k) mixed layer conjugated efficiently with the maleimide-installed proteins and the antibody Fab' fragments, accompanied by an appreciable nonfouling characteristic against bovine serum albumin as strong as that of the MeO-PEG-SH (5k)/MeO-PEG-SH (2k) mixed surface, which was reported in our previous work; it also showed a superior nonfouling characteristic compared to the commercially available carboxymethylated dextran surface (Uchida, K.; et al. Biointerphase 2007, 2 (4), 126-130). Furthermore, from the experimental results of the X-ray photoelectron spectrometry analysis, the presence of both Au-bound and Au-unbound sulfur species was confirmed on the SH-PEG-SH (5k)/MeO-PEG-SH (2k)-modified gold surface. These results clearly indicate that the preimmobilized shorter MeO-PEG-SH (2k) not only increased the nonfouling characteristic of the PEG tethered-chain surface but also prevented loop formation in the longer SH-PEG-SH (5k) on the gold surface. Since the protein-installed SH-PEG-SH (5k)/MeO-PEG-SH (2k)-modified surface showed a strongly nonfouling characteristic and recognized the target molecules selectively, this new mixed-brush-formation technique using longer sulfanyl-ended telechelic PEGs and shorter semitelechelic PEGs is a simple yet effective method of constructing a strongly nonfouling terminal-functionalized gold surface for protein immobilization.     

A new process for producing polyamide from polyester

A new process for producing polyamide from polyester and diamine was proposed. An attempt was made to produce polyamide 6T from polyethyleneterephthalate or dimethylterephthalate with hexamethylenediamine in water, o‐dichlorobenzene and sulfolane. Characterization of the products by IR, elemental analysis, solution viscosity and GPC were carried out. It became clear that high molecular polyamide 6T could be obtained from polyethyleneterephthalate and hexamethylenediamine in sulfolane. The reaction mechanism was discussed from the viewpoint of the polymer effect and solvent effect. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1413–1423, 1999