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On-chip blood plasma separators using microfluidic channels are typically developed as disposable devices for short-term use only because blood cells tend to clog the microchannels, limiting their application in real-time and continuous systems. In this study, we propose an anti-clogging method. We applied dielectrophoresis to prevent microchannel clogging in a plasma separator that can be used over long periods for real-time and continuous monitoring. Prior to applying the anti-clogging method, the blood plasma separator stopped working after 4 h. In contrast, by manipulating the separator with the new anti-clogging method at a voltage of 20 V, it continued working in a long-term experiment for 12 h without performance deterioration or an increase in cell loss. Two critical performance parameters of the manipulated separator, the purity efficiency and the plasma yield, were 97.23 ± 5.43% and 38.95 ± 9.34%, respectively, at 20 V after 15 min. Interestingly, the two performance parameters did not decrease during the long-term experiment. Hence, the blood plasma separator with the anti-clogging method is an interesting device for use in real-time and continuous blood plasma separation systems because of its consistent performance and improved lifespan.

[Purpose] The purpose of this study was to determine the influence of complex exercise and chromium supplement on healthe-related physical fitness, appetite regulating hormones, and diabetes risk factors in obese elementary school students. [Methods] The subjects were 32 obese elementary students over 25 kg/m2 to BMI, 8 complex exercise with high chromium supplement group (CE+HC), 8 complex exercise with low chromium supplement group (CE+LC), 8 complex exercise with placebo group (CE+PL), and 8 placebo group (PL). The subjects have performed the exercise program for 70 minutes a day and 3 times a week with aerobic and anaerobic exercise during 12 weeks. Also, low and high chromium supplement group took a peel 50 ug and 400 ug respectively at the same time and place. [Results] There were significant decreases in body fat to CE+HC compared with CE+PL (p

To achieve real-time monitoring of aerodynamic submicron particle size distributions at a point-of-interest, we developed a high-performance particle size spectrometer that is compact, low-cost, and portable. The present system consists of four key components: a unipolar mini-discharger for electrically charging particles, an inertial size-separator for classifying charged particles into five size fractions in terms of their aerodynamic sizes, a portable multi-channel electrometer for detecting femto-ampere currents carried by charged particles at each stage, and a retrieval algorithm for converting the current data into a smooth particle size distribution. The unipolar mini-discharger and inertial size separator were quantitatively characterised by using standard polystyrene latex (PSL) particles. The experimentally determined cut-off diameters at each stage in the inertial size separator were 1.17, 0.94, 0.71, 0.54, and 0.23 μm, respectively. Then, the system was compared with a commercial reference aerodynamic particle sizer (APS) in the environment where the number concentration and the average size of TiO2 particles were changing. The present system resolved peak size and geometric standard deviation of particles to within 11.2%, and 6.3%, respectively, indicating that the system can be used to accurately monitor submicron particle size distributions in real time.

This paper reports an ammonia cross-sensitivity elimination filter for SCR systems. Since NO X sensors are cross sensitive to NH 3 , a reading of NO X sensor could not be accurate. As the reading is inaccurate, the closed-loop SCR systems is unpredictable. The proposed filter can be applied to any kinds of NO X sensors and effectively remove the cross-sensitivity. Single gas and mixed exhaust gas tests are conducted. The results show the evident removal of NH 3 in both single gas and mixed gases experiments. The experiments show the filtering method can considerably improve the accuracy of NO X concentration measurement in Urea-SCR systems.

This paper reports a MEMS based particle size analyzer using electrostatic measuring techniques. The MEMS based particle size analyzer is able to classify particles of same diameter by using electrical mobility and measure particle size distribution in the size range of 50 to 300 nm. The performance of the proposed device was evaluated through measurements of particle size distribution and compared with commercial high precision instruments.

Nanoparticle monitoring is very important due to their serious health hazard, while personal devices for monitoring them have not been developed yet. To accurately monitor airborne nanoparticles at points of interest on real-time basis, we developed a high-performance MEMS-based condensation particle counter (CPC). Our system could detect extremely small particles (8.6 nm) with high accuracy (deviation within 3.8 % in number concentration), showing high performance comparable to the reference CPC.

We fabricated and characterized microelectromechanical systems (MEMS)-based Ni–B probes with enhanced mechanical properties for fine pitch testing. The Ni–B micro-probes were compared with conventional Ni–Co micro-probes in terms of the mechanical performance and thermal effect. The elastic modulus and hardness of Ni–B were found to be 240.4 and 10.9 GPa, respectively, which surpass those of Ni–Co. The Ni–B micro-probes had a higher contact force than the Ni–Co micro-probes by an average of 41.38% owing to the higher elastic modulus. The Ni–B micro-probes had a lower average permanent deformation than the Ni–Co micro-probes after the same overdrive was applied for 1 h by 56.58 µm. The temperature was found to have a negligible effect on the Ni–B micro-probes. These results show that Ni–B micro-probes are useful for fine pitch testing and a potential candidate for replacing conventional Ni–Co micro-probes owing to their advanced mechanical and thermal characteristics.

This paper proposes a microfluidic channel for particle focusing that uses a microstructure on the bottom of the channel. Particles can be effectively focused in channels with bottom structures because of microvortex induced by the structure. Microchannels with top structures (top type) and bottom structures (bottom type) were fabricated. The focusing ratios in the focusing region (one-eighth of the channel width) were 86 % in top type and 89 % in bottom type at a flow rate of 1 μl/min. When the flow rate was increased to 5 μl/min, particles in top type were barely focused, whereas particles in bottom type were focused with a focusing ratio of approximately 80 %. We also evaluated the effect of a slanted angle for the microstructures. The comparative experiment was conducted with microstructures fabricated at slanted angle intervals of 20° (20°, 40°, 60°, and 80°) and 10°. The results indicated that the slanted angle (20°) required a small number of microstructures to direct the sample to the focusing region. For microstructures with a 20° slanted angle, the sample was focused after passing through 20 microstructures (10 mm). However, microstructures with an angle of 80° needed over 70 microstructures (over 23 mm) to direct the particle. In this sense, a microchannel with microstructures slanted at 20° is applicable to miniaturized devices. These results show that the microchannel with bottom structures slanted 20° can be used to effectively focus samples with advantages of applying various ranges of flow rates and miniaturizing devices.

Treatment of β-aryl-β-(benzotriazol-1-yl)-α-primary alkyl (or aryl)-α,β-unsaturated ketones 1 with n-Bu3SnH (4 equiv) in a catalytic amount of AIBN in PhH at reflux afforded 3-alkyl (or aryl)-2-arylindoles 8 in good yields. However, when tert-butyl group is bonded at α-position, 3-acyl (or aroyl)-2-arylindoles 9 were obtained as major products along with phenanthridines 5 as minor products.

Microfluidic devices for plasma extraction are popular because they offer the advantage of smaller reagent consumption compared to conventional centrifugations. The plasma yield (volume percentage of plasma that can be extracted) is an important factor for diagnoses in microdevices with small reagent consumptions. However, recently designed microfluidic devices tend to have a low plasma yield because they have been optimized to improve the purity of extracted plasma. Thus, these devices require large amounts of reagents, and this complexity has eliminated the advantage of microfluidic devices that can operate with only small amounts of reagents. We therefore propose a continuous, real-time, blood plasma separation device, for plasma extraction rate enhancements. Moreover, a blood plasma separation device was designed to achieve improved plasma yields with high-purity efficiency. To obtain a high plasma yield, microstructures were placed on the bottom side of the channel to increase the concentration of blood cells. Plasma separation was then accomplished via microfluidic networks based on the Zweifach–Fung effect. The proposed device was fabricated based on the polydimethylsiloxane molding process using the SU-8 microfluidic channel for the fabrication of the mold and bottom structures. Human blood diluted in a phosphate buffered saline solution (25% hematocrit) was injected into the inlet of the device. The purity efficiencies were approximately equal to 96% with a maximum of 96.75% at a flow rate of 2 µl min−1, while the plasma yield was approximately 59% with a maximum of 59.92% at a flow rate of 4 µl min−1. Compared to results obtained using other devices, our proposed device could obtain comparable or higher plasma purity and a high plasma yield.

The effects of carbon nano-tubes (CNTs) on the crystal structure and superconducting properties of YBa 2 Cu 3 O 7− δ (Y-123) compound were studied. Samples were synthesized using standard solid-state reaction technique by adding CNT up to 1 wt% and X-ray diffraction data confirm the single phase orthorhombic structure for all the samples. Current–voltage measurements in magnetic fields up to 9 T were used to study the pinning energy U J and critical current density J c as a function of magnetic field at fixed temperature. We find that while T c does not change much with the CNT doping (91–92 K), both U J and J c increase systematically up to 0.7 wt% CNT doping in a broad magnetic field ranges between 0.1 and 9 T and J c in the 0.7 wt% CNT doped sample is at least 10 times larger than that of the pure Y-123. The scanning electron microscope image shows that CNTs are forming an electrical-network between grains. These observations suggest that the CNT addition to the Y-123-compounds improve the electrical connection between superconducting grains to result in the J c increase.

SrRuO3 thin films have been grown in-situ on and LaAIO3 textured metal templates by pulsed laser deposition. Deposition was carried out between 3 mTorr to 300 mTorr of oxygen partial pressure with laser repetition rate of 5 Hz. Substrate temperature was between 500 and 800degC . Dependence of out-of plane orientation SrRuO3 of thin films on pressure and growth temperature is investigated by X-ray diffraction. The surface morphology and grain growth behaviors of thin films are analysed by atomic force microscopy. In addition, a ferromagnetic transition at ~150 K SrRuO3 of films on LaAIO3 is detected by resistivity and magnetization measurement.

3,3′:4′,3″-Ter-1,2,5-thiadiazole, an useful oligoheterocyclic compound, has been accomplished in seven steps from 1-(5-methyl-3-isoxazolyl)ethanone or diethyl acetylenedicarboxylate using a synthetic utility of tetrasulfur tetranitride antimony pentachloride (S4N4·SbCl5) complex to make a 1,2,5-thiadiazole ring.

Superconducting MgB 2 fibers are grown by a diffusion method, in which B filaments are exposed to Mg vapor inside a folded Ta foil over a wide range of temperature and growth time. The as-grown wires with a diameter of about 110 μm are characterized by scanning electron microscopy and energy dispersive X-ray analysis. Surface morphology of the fibers turns out to be dependent on growth temperature and mixing ratio of Mg and B. Radial distribution of Mg ions into B is observed over the cross-sectional area. Transport properties of the MgB 2 fibers are investigated in magnetic fields from 0 to 8 T by use of a physical property measurement system. MgB 2 fibers grown at 900 °C for 2 h show a superconducting transition at 38.1 K with an onset temperature as 41.7 K and ΔT c < 3.03 K. Resistance of the MgB 2 fiber at room temperature is 4 Ω and residual resistivity ratio (RRR) is estimated as 4.72. It is estimated that the upper critical field H c2 at 4 K is more than 16 T. In addition, a small amount of magneto-resistance is detected at high magnetic fields.

Diarylethenes with donor–acceptor groups were synthesized to induce electrochemical switching by light. Photoisomerization was induced by 1,2-bis(2-methyl-1-benzo[ b ]thiophen-3-yl)perfluorocyclopentene (BTF, 1 ) unit, while the 3,4-ethylenedioxythiophene (T) and nitro (N) groups were directly connected to BTF, to extend π-electron delocalization. Spectral change to a longer wavelength through photochromism was significant in the donor–acceptor structures ( 6 ), accompanied by an increase in the molar absorption coefficients, than those of the unsubstituted BTF ( 1 ) or the BTF substituted with only acceptor group ( 2c and 3c ). A significant peak shift toward lower redox energy was observed when the molecules were converted from an open isomer to a closed isomer. The plot of the reduction potentials (( E 1/2 red , V vs Ag/AgCl) vs LUMO energy eV) for the diarylethenes indicates that the reduction potential is strongly dependent on the nature of the substituents around the diarylethene unit. When 6 was applied to a photocell of Au/PC/ITO glass, in which PC is the polystyrene containing 6 , it became possible to switch the conductivity of the cell through the film by UV–vis irradiation, as estimated by the I–V plot on a photocell. The conductivity of the cell exposed to UV light was three times larger than that of the cell exposed to visible light, and 10 times larger than that of the cell containing 3 , indicating the importance of the push–pull structure for π-electron connectivity through the donor–BTF–acceptor.

Treatment of a solution of a mixture of 1-aryl-2-arylsulfonylethanones 9 and alkylsulfonyl chlorides (1.5-2.0 equiv) in THF at 0 degree C with potassium hydroxide (8 equiv) for 10 min gave a rearrangement product, i.e., 1-aryl-2-(arylsulfonylmethanesulfonyl)ethanones 8, in excellent yields. Regiospecific methyl- and ethylation at the methylene carbon sandwiched between two sulfonyl groups of 8 could be achieved by the reactions of 7i-j with LDA (1 equiv) in THF at room temperature, respectively.

Treatment of 5-arylthianthrenium perchlorates 2 with secondary alkylamines in the presence of LDA in THF at reflux gave 2-(arylthio)-3'-(dialkylamino)diphenyl sulfides 7 as major products along with 2-(arylthio)-2'-(dialkylamino)diphenyl sulfides 8 and thianthrene. The latter two compounds were formed depending on the structures of amines employed and the concentrations of LDA. It has been found that the methoxy groups of 7e, 7g, and 7h were displaced by amide ions in the presence of excess amounts of LDA to give the corresponding 2-(4dialkylaminophenylthio)-3'-(dialkylamino)diphenyl sulfides (14a-c). The reactions with aza-15crown-5, aza-18-crown-6, and 7, 16-diaza-18-crown-6 gave analogous products via a benzyne intermediate. The affinity of selected metal cations for compounds 7a, 7e-f, 7h, 7j, 7m, 10, 13a, and 18a was examined by an extraction method. The dialkylamino groups of 7a, 7e, 7f, and 7h increased somewhat the extractive abilities of Ag + ion (14 - 28%) compared with that of 10 (8%), whereas compound 13a having a diisopropylamino group showed low (9%) and high (67%) extractive abilities toward Ag + and Pb 2+ ions, respectively. Compounds 7j and 7m having an aza-18-crown6 moiety showed 67% and 66% extractive abilities toward Pb 2+ but 40% and 24% extractive abilities towards Ag + ions, respectively. However, compound 18a with two identical lariats showed high (86%) and low (12%) extractive abilities toward Ag + and Pb 2+ ions, respectively.

Reactions of methyl N -(4-chloro-5 H -1,2,3-dithiazol-5-ylidene)anthranilates with tryptamine at room temperature produced 2-cyano-3-[2-(indol-3-yl)ethyl]-4(3 H )-quinazolinones, which underwent cyclization on heating with TFAA/HCl(g) to afford quinazolinocarboline alkaloids rutaecarpine ( 1a ), hortiacine ( 1b ), euxylophoricine A ( 1c ) and euxylophoricine D ( 1d ) in excellent yields.

Treatment of 2-alkyl (and aryl)-3-aryl-3-(benzotriazol-1-yl)allylic selenides with m-CPBA (1 equiv.) for 10 min in CH2Cl2 at rt gave 2-alkyl (and aryl)-1-aryl-2-propen-1-ones in excellent yields.

Treatment of [(alkylamino and anilino)(cyano)methylene]-2,2-dimethyl-1,3-dioxane-4,6-diones with benzyl alcohol for 20 min at reflux gave 3-(alkylamino and anilino)-4-benzyloxycarbonylmaleimides.

Treatment of 1-(arylmethyl)benzotriazoles 1 with nBuLi in THF at −78 °C, followed by addition of 1-aryl-2-chloroethanones, gave diastereomeric mixtures of 1-[(aryl)(benzotriazol-1-yl)methyl]oxiranes 2. Treatment of 2 with nBuLi in THF at −78 °C, followed by acidification, afforded a mixture of (E)- and (Z)-allylic alcohols 3, which were converted into 1,2-disubstituted 2-(alkyl- or aryl)-1-(benzotriazol-1-yl)-3-sulfanylpropenes 5 via the corresponding allylic chlorides 4. Oxidation of sulfides 5 by mCPBA in CH2Cl2 at room temperature, followed by treatment with trifluoroacetic anhydride (TFAA) at room temperature, gave the title compounds in good yields. It was found that treatment of the title compounds with Raney-Ni in EtOH under hydrogen at reflux gave 2-(pyrazol-1-yl)aniline derivatives in excellent yields.

Treatment of 3-methylamino-3-methylsulfanyl-1-phenylpropenethione 1 with excess (2.5 equiv.) α-diazo carbonyl compounds such as α-diazoketones and α-diazoesters in the presence of a catalytic amount of Rh(II) acetate in CH2Cl2 at rt gave 2-acyl- or 2-aroyl-3-methylamino-5-phenylthiophenes and alkyl 3-methylamino-5-phenylthiophene-2-carboxylates, respectively, as major products along with 1-phenyl-2-methylsulfanylethanones. The formation of the major products indicates that the carbenes or carbenoids generated interact initially with the thione sulfur of 1.

Treatment of methyl N-(4-chloro-5H-1,2,3-dithiazole-5-ylidene)anthranilate 1 with TiCl 4 (1.5 equiv.) in CH 2 Cl 2 at r.t., followed by addition of arylamines gave quinazolin-4-ones 2 bearing an aryl group at position 3 inmoderate yields. Similarly 4-hydroxy-4-phenylquinazolines 6 bearing an aryl group at position 3 were prepared in good to moderate yields from 2-[N-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)(benzophenones, 5, TiCl 4 , and arylamines under the same conditions. The 1 H NMR spectra of 6 in CDCl 3 indicate that the compounds exist as an equilibrium mixture of 6 and the corresponding ring-opened compound, N-(2-benzoylaryl)-2-cyano-amidines 7. However, it is envisaged that compounds 6 exist as a single compound in a solid state in view of IR spectra showing no peak corresponding to a carbonyl absorption.

Treatment of 4-chloro-5H-1,2,3-dithiazol-5-one with primary and secondary alkylamines (>2 equiv.) in CH2Cl2 at rt afforded symmetrical N,N′-disubstituted ureas in moderate to good yields. Similarly, the reactions with amino acid ester hydrochlorides in the presence of Et3N (>3 equiv.) under the same conditions gave symmetrical ureas.

Medium-sized thienolactams can be directly prepared from thiobenzoylketene S,N-acetals, Hg(OAc)2, and silyl enol ethers of cyclic ketones, and either TBAF or TASF. However, by adding either water or alcohol to the foregoing mixture, 3-methylamino-5-phenylthiophenes, in which the ω-position of long-chain alkanoic acids and alkanoic esters are bonded to C-2 of the thiophene ring, can be obtained albeit in low yields. Sequential treatment of the thienolactams with Raney nickel and Adam's catalyst results in completely reductive desulfurization of thienolactam molecules.

Treatment of alpha-aryl-beta-bromo(or chloro)-alpha-nitrosoethylene, prepared in situ from alpha-monobromo(or chloro)ketoximes and sodium carbonate in ether at rt, with allytrimethylsilane afforded exclusively trans-(4S,6S)- and trans-(4R,6R)-3-aryl-4-halo-6-[(trimethylsilyl)methyl]-5,6-dihydro-4H-1,2-oxazines 10 albeit in low yields. Similar treatment of beta-halo-alpha-nitrosoethylenes with ethyl vinyl ether, however, gave single stereoisomers, i.e., cis-(4S,6S)- and cis-(4R,6R)-6-ethoxy-4-halo-5,6-dihydro-4H-1,2-oxazines 11, in moderate to good yields. The result is in contrast to the reported predominant formation of trans-11a by a radical reaction. On the other hand, similar reactions with tert-butyl vinyl ether at 30 degrees C gave diastereomeric mixtures of cis-(4S,6S)-, cis-(4R,6R)-, trans-(4S,6R)-, and trans-(4R,6S)-6-(tert-butoxy)-4-halo-5,6-dihydro-4H-1,2-oxazines 12. In contrast to compounds 11, the major isomers have (4S,6R) and (4R,6S) configurations. The tendency of a [4 + 2] cycloaddition reaction is consistent with that observed in the Diels-Alder reaction with inverse-electron demand. The stereochemistries of compounds 10-12 were assigned on the basis of the (1)H NMR coupling constants, which were unambiguously determined by the decoupling experiments. All reactions leading to compounds 10-12 proceed with very high regioselectivity. Diastereoselectivity and high regioselectivity are understood in terms of the frontier orbital method. It has been found that cis-12g is isomerized to a mixture of stereoisomers in favor of the trans-isomer in the presence of HClO(4) (72%) in CHCl(3) at rt.

N -Acetyl- N -methyl-3-aryl-3-[1-(aroyl)ethylthio]-2-propaneamides, prepared from thioaroylketene S , N -acetals, Hg(OAc) 2 and silyl enol ethers of aryl-1-propanones in CH 2 Cl 2 at rt, reacted with NaH in THF to give the title compounds in excellent yields.

Treatment of 3-methylamino-5-phenylthiophene with α,β-unsaturated esters, i.e., methyl acrylate, (E)-methyl crotonate, diethyl fumarate, diethyl maleate and ethyl propiolate, in tetrahydrofuran for several days at reflux gave 1-methyl-3,4-dihydrothieno[2,3-e]pyridin-2-ones 4 and/or 1-methylthieno[2,3-e]pyridin-2-ones 5, depending on the structure of the esters. On the other hand, the same reactions with α,β-unsaturated nitriles such as acrylonitrile and tetracyanoethene, gave the corresponding thiophenes 7 and 10 bearing 2-cyanoethyl and 1,2,2-tricyanoethenyl groups at C-2, respectively. The reaction with (Z)-1,2-dicyanoethene under the same conditions produced the corresponding thiophene 9 bearing the 1,2-dicyanoethenyl group and 1,2-dicyano-5-methylaminobiphenyl.

The reactions of 5-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione with primary alkylamines (2 equiv.) in CH2Cl2 at rt gave 5-[(alkylamino)(cyano)methylidene]-2,2-dimethyl-1,3-dioxane-4,6-diones (2) in excellent yields. Similarly, the reactions with ethylenediamine, trans-1,2-diaminocyclohexane, 2-aminobenzylamine, and 2-aminoethanol under the same conditions afforded 5-(imidazolidin-2-ylidene)- (3a), 5-(octahydro-2H-benzimidazol-2-ylidene)- (3b), 5-[3,4-dihydroquinazolin-2(1H)-ylidene]- (3c), and 5-(1,3-oxazolidin-2-ylidene)-2,2-dimethyl-1,3-dioxane-4,6-diones (3d) in moderate to excellent yields. Interestingly, the reactions with secondary acyclic dialkylamines under the same conditions yielded 5-(4-dialkylamino-5H-1,2,3-dithiazol-5-ylidene)-2,2-dimethyl-1,3-dioxane-4,6-diones (7) (0–60%), 6-carbamoyl-5-oxo-5H-furo[2,3-d][1,2,3]-dithiazoles (8) (0–28%), sulfur, and bis(dialkylamino) sulfides (R2N–Sx–NR2), whereas the reactions with cyclic amines, i.e., pyrrolidine and piperidine, gave the corresponding methylidene-Meldrums acid derivatives 9, analogous to 2, as major products. Mechanisms are proposed for the formation of these products.

Dithiatetraoxa-1a, dithiapentaoxa-1b, dithiahexaoxa-1c, bis-dithiapentaoxa-18, and tris-dithia-pentaoxa-crown ethers 22 were synthesized in order to study the complexation of bis-and tristhiacrown ethers in which the cycles are bounded to the same carbon atom, with metal picrates. Measurements of the affinity of meial ions (Cs+, Rb+, Ba2+, K+, Ag+, Pb2+, Sr2+, Ca2+, Cu2+, Mg2+), to these molecules represented by extractability, defined by equation 1, showed that Ag+ was strongly attracted by 1a (95%), 1b (94%), 1c (65%), 18 (193%), and 22 (270%). It appeared that the extractability increased linearly with the number of cavities in the molecule (cf. Mono-1b, bis-18, and tris-crown ethers 22). However, extractabilities of Pb2+ shown by only 21-membered 1b, 18, and 22, in spite of much lower values than those of Ag+, were not additive, For noncompetitive transport of metal ions (Ba2+, Ag+, Pb2+) through a liquid membrane, 1a favored transport of Ag+ over Pb2+. However 1b-c favored transport of Pb2+....

Treatment of allylic esters such as allyl benzoate ( 3a ), allyl phenylacetate ( 4 ), allyl 3-phenylpropanoate ( 5 ), crotyl esters 14 , 4-bromo-2-butenyl esters 15 , and 1,4-bis(aroyloxy)-2-butenes 16 with NOBF 4 in CH 3 CN at −23°C gave alkanoyloxy (or aroyloxy)-2-isoxazolines and 3-substituted 4-alkanoyloxy (or aroyloxy)-2-isoxazolines, depending on the allylic esters.

A variety of5-alkylidene-4-chloro-5H-1,2,3-dithiazoles (9–25) have been prepared from4-chloro-5H-1,2,3-dithiazolium chloride, active methylene compounds, and pyridine. The reactions with ethyl nitroacetate ((Z) > (E)), ethyl 3-nitrobenzoylacetate ((E) > (Z)), ethyl 2-fluorobenzoylacetate ((E) > (Z)), and tetronic acid ((Z) > (E)) gave a mixture of(E)-and(Z)-isomers, whereas those of benzoylnitromethane (Z),5,6-dihydro-4-hydroxy-6-methyl-2H-pyran-2-one (E), 4-hydroxy-6-methyl-2-pyrone (E), 4-hydroxycoumarin (E), 6-chloro-4-hydroxycoumarin (E), and 6-bromo-4-hydroxycoumarin (E) afforded only single stereoisomers. The reactions with4-hydroxy-1-methyl-2(1H)-quinolone, 2-hydroxy-1,4-naphthoquinone and homophthalic anhydride gave only single stereoisomers whose stereochemistry is uncertain. It appears that geometrically more rigid cyclic 1,3-dicarbonyl compounds give better yields of dithiazol-5-ylidenes than the corresponding acyclic compounds. Download : Download full-size image

Treatment of 4-chloro-5 H -1,2,3-dithiazol-5-one with 3-alkyl (or aryl)-3-amino-2-propenoate esters in DMSO at 120°C gave the corresponding 2-thiocyanated esters 4 (major) and 5-alkoxycarbonyl-4-alkyl (or aryl)-4-thiazolin-2-ones 5 (minor), whereas the esters bearing a strong electron-withdrawing group at C-3 under the same conditions afforded 5 and/or 4-substituted 5-alkoxycarbonyl-2-aminothiazoles 6 , depending on the electron-withdrawing groups.

Treatment of arylglyoxal monohydrates with tetrasulfur tetranitride in p-dioxane at reflux afforded 2-aroyl-5-arylimidizoles and 2-aroyl-5-aryloxazoles in 10 to 31% and 17 to 32% yields, respectively. With non-hydrate of arylglyoxals, yields of the latter increase somewhat, whereas essentially no changes in yields of the former were observed. A mechanism is proposed for the formation of the products.