Abstract  Two novel monofullerene-bis(pyropheophorbide a) complexes were synthesized and their photophysical properties were studied by using both steady-state and time-resolved techniques. It was revealed that in the pyropheophorbide a (pyroPheo)-C-60 molecular system (FP1) strong quenching of the first excited singlet state of the pyroPheo and, as result, dramatically decreasing of photosensitized singlet oxygen generation occurs by efficient photoinduced electron transfer to the fullerene molecule with a rate constant of 2.5 x 10(9) s(-1). In contrast, the fullerene hexaadduct-bis(pyroPheo) system (FHP1), which possesses five diethyl malonate addends in the remaining octahedral positions, shows a high singlet oxygen quantum yield which is due to the reduced fullerene chromophore which is not a good electron acceptor anymore. (C) 2004 Elsevier B.V. All rights reserved.

Abstract  The organic functional groups such as primary and quaternary amine, sulfonic acid, and amino acid, especially l-proline, have been tried to immobilize onto mesoporous materials by the direct synthesis method using microwave. Microwave induced direct functionalization enabled to get well ordered mesoporous structures and stable organic tethered groups with enhanced hydrothermal stability due to more hydrophobic surfaces as well as enhanced activity. The method is also useful for overcoming several shortcomings in the post-synthesis grafting method which suffers from pore blocking at the aperture, and difficulties in controlling the as obtained from the direct co-condensation method had their functional groups spatially loadings, as well as the dispersion of active sites. The organo-functionalized mesoporous silica dispersed on the surface which could play roles as single site catalysts. Direct tethering of organic functional groups was preferably synthesized by microwave, gave morphological control and illustrated superiority in some organocatalytic application such as Knoevenagel and Henry reactions base catalytic reaction, Claisen-Schmidt condensation, and diethyl malonate addition reactions.

Abstract  The pollen beetle, Meligethes aeneus F. (Coleoptera: Nitidulidae) and the cabbage seed weevil, Ceutorhynchus assimilis (Payk.) (Coleoptera: Curculionidae) are two most dangerous winter rape pests in Europe, which frequently co-occur on fields. Difficulties in controlling both pest species stem not only from their resistance to various active ingredients of insecticides, but also from significant differences in their susceptibility to the same active ingredients. The aim of our research was to establish the level of susceptibility of the pests to deltamethrin, a pyrethroid, and indoxacarb, an oxadiazine, and to determine enzymatic mechanisms of resistance to indoxacarb in the cabbage seed weevil, using pesticide synergists that block particular groups of enzymes. The results have shown that the pollen beetle was highly resistant to deltamethrin and highly susceptible to indoxacarb, while the cabbage seed weevil was highly susceptible to deltamethrin and highly resistant to indoxacarb. Studies of resistance mechanisms to indoxacarb in the cabbage seed weevil have not indicated participation of oxidative enzymes blocked by piperonyl butoxide, esterases blocked by S,S,S-tributylphosphorotrithioate or glutathione transferases blocked by diethyl malonate in the metabolism of this substance. Thus, further research on mechanisms behind the resistance of the cabbage seed weevil to indoxacarb is necessary.

Abstract  The mechanistic details of Mn(OAc)(3)-based oxidative free-radical additions and cyclizations are reviewed. The mechanisms of electron transfer to generate radicals, electron transfer to convert the radicals to oxidized products, and further oxidation of the products are covered.

Abstract  The Tsuji-Trost reaction between diethyl malonate and allyl acetate catalyzed by palladium(II) NPN-aminoiminophosphoranate complexes yields mono- and diallylation products in the ratios depending on the complex used. The Suzuki-Miyaura cross-coupling of 4-bromoacetophenone with phenylboronic acid catalyzed by these palladium complexes proceeds with 66-99.5% conversions.

Abstract  A variety of thieno[2,3-b]thiophenes were prepared under phase-transfer catalysis conditions. The reaction of diethyl 3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylate with hydrazine hydrate gave the corresponding hydrazide derivative which was also subjected to react with acetylacetone, ethyl acetoacetate, malononitrile, CS2, phenyl isothiocyanate, p-chlorobenzaldehyde and diazotization to afford the described compounds. Treatment of 2,5-bis(azidocarbonyl)-3,4-dimethylthieno[2,3-b]thiophene with ethyl cyanoacetate, diethyl malonate or malono-nitrile gave the corresponding triazole derivatives.

Abstract  Electrochemical oxidation of malonic esters in acetonitrile in the presence of iodides follows two different pathways depending on the nature of the cation. In the presence of LiI, alkyl 1,1,2,2,3,3-propanetetracarboxylates were obtained in 85-98% yields. In the presence of Nat, KI, or Bu4NI, the formation of 1,1,2,2-ethanetetracarboxylates and their subsequent dehydrogenation to ethenetetracarboxylates was the main reaction pathway.

Abstract  Acrylamide and N,N'-methylenebis (acrylamide) (AAm-Bis) copolymerization has been investigated in water at a total monomer concentration of the 0.5 M. Conversion of monomer was measured as a function of the reaction time up to the onset of macrogelation. Experimental results indicate that the critical conversion at the gel point shows a minimum at 6 mol.% Bis when the monomer concentration was kept constant at 0.5 M and it was found that polymer formed with different Bis% are not dissolved in water, acetic acid, toluene or chloroform. (C) 2001 Published by Elsevier Science Ltd.

Abstract  The synthesis of 4,5-dihydro-1H,3H-cycloprop[f]inden-4-ol (1) and diethyl 4,5-dihydro-1H,3H-cycloprop[f]indene-4,4-dicarboxylate (26) starting from diene 4 is described. The cyclopentene ring is constructed by condensation of diethyl malonate to the dibromide 21. The key-step in the synthesis of 1 consists in a twofold Curtius degradation of 22, with subsequent reduction of the carbonyl group and aromatization. The skeleton of the isomer 31 is synthesized via cycloaddition of butadiene to cyclopent-4-ene-1,3-dione (7) and addition of dichlorocarbene to the adduct 27 after ketalisation. The attempted synthesis of dihydrocycloprop[f]indene (2) by base-induced elimination of several appropriately substituted precursors failed.

Abstract  Condensation of 3-azidobenzo[b]thiophene-2-carbaldehyde 1 with acetone, diethyl malonate, ethyl acetoacetate and pentane-2,4-dione furnished the 3-azido-2-vinylic derivatives 4a-d in fairly good yields. In refluxing toluene the azides 4a, b,d smoothly gave solely fused pyrrole products, 5a, b, d, whereas the azide 4c furnished an isomeric mixture of the cyclized pyrroles 5c and 6. The observed 1H-pyrroles 5a-d and 6 are assumed to occur through aromatization of initially formed 2H-pyrroles 7a-d. Attempted condensation of 2-azidobenzo[b]thiophene-3-carbaldehyde 2 with acetone or pentane-2,4-dione gave no vinylic product, but instead resulted in reduction of the azide 2 to the amine 8 or in its conversion into the 1,2,3-triazole adduct 9, respectively.

Azido group transfer of 3-styrylbenzo[b]thiophene with tosyl azide yielded the ortho-vinyl-substituted azide 10, but in poor yield. Thermolysis of the azide 10 gave quantitatively the benzothiopyran 12 clearly ascribable to an initial ring-opening reaction. It is therefore inferred that, in the presence of ortho-vinyl substituent, an alpha-azidobenzo[b]thiophene can exhibit 'normal' ring-cleavage fragmentation, in contrast with previous deoxygenations of 2-nitro-3-vinylbenzo[b]thiophenes reported to yield cyclized benzothieno[2,3b]pyrroles. Evidence is also presented that, upon thermolysis, the o-azidoaldehyde 1 cleanly affords a benzothienoisoxazole product, whereas the isomeric azide 2 essentially leads to intractable material.,

Abstract  The enantioselective Michael addition of dimethyl malonate to 1,3-diphenylprop-2-en-l-one promoted by a quaternary derived ammonium salt from quinine as a phase transfer catalyst in different ionic liquids, 1-butyl-3-methyl imidazolium hexafluorophosphate, [bmim]PF6, 1-butyl-3-methyl pyridinium tetrafluoroborate, [bpy]BF4, 1-butyl-3-methyl imidazolium tetrafluoroborate [bmim]BF4 as well as in conventional organic solvents was studied. (C) 2003 Elsevier Science Ltd. All rights reserved.

Abstract  Enantioenriched benzyl esters of propiolic acids undergo highly stereospecific decarboxylative coupling to provide 1,1-diarylethynyl methanes. This sp-sp(3) coupling does not require strongly basic conditions or preformed organometallics and produces CO2 as the sole byproduct. Ultimately, this method results in the successful transfer of stereochemical information from secondary benzyl alcohols to generate enantioenriched tertiary diarylmethanes.

Abstract  Manganic acetate and potassium methyl malonate with a 2-substituted dihydropyran provide the corresponding fused gamma-lactone in good yield. Carboxylic acids with less acidic methylene protons fail in this reaction.

Abstract  Addition of thiols or diethylmalonate to thiocinnamate, under solid-liquid PTC conditions, afforded the corresponding 1,4-adducts in moderate to good yields. A 2-pyrrolidinone was obtained using diethyl N-acetamidomalonate as Michael donor, via intramolecular cyclization of the parent adduct.

Abstract  A synthesis of ferrocenyl-oxazolines is described using an iodide-mediated ring expansion of N-ferrocenoyl-aziridine-2-carboxylic esters. The ring enlargements take place with full stereocontrol, namely net retention of configuration. Modification of the ester function by a Grignard reaction leads to three new types of ferrocenyl-oxazoline carbinol ligands, which were used as chiral ligands in the asymmetric addition of diethylzinc to benzaldehyde (e.e.s ranging from 46 to 62%). The planar chiral ferrocenyl-oxazoline carbinol ligand gave a very good result (e.e. 90%) in the palladium-catalyzed allylic substitution of 1,3-diphenyl prop-2-enylacetate with dimethyl malonate. (C) 2003 Elsevier Ltd. All rights reserved.

Abstract  Mesoporous MCM-41 containing intraporous cesium oxide particles have been prepared by impregnation of aqueous cesium acetate and subsequent calcination, and characterized by Cs-133 MAS NMR, CO2 temperature programmed desorption and nitrogen physisorption. The amount of framework aluminum of the MCM-41 support appeared to be very important regarding the strength of the basic sites. The Michael addition of diethyl malonate to neopentyl glycol diacrylate catalyzed by MCM-41 supported cesium oxide showed a high regioselectivity, in contrast to bulk cesium oxide.

Abstract  NOABSTRACT - no abstract found

Abstract  Pyrazolo[3,4-b]pyridine-5-carbonitrile derivative 1 was diazotized to give the corresponding diazonium salt 2 which was used as a good synthon to synthesize pyrido[2',3':3,4]pyrazolo[5,1-c]triazines 5, 8, 15a-c and 19 via its coupling with several active-hydrogen containing reagents e.g. 2,4-pentanedione, ethyl 3-oxobutanoate, diethyl malonate, malononitrile, 2-cyanoethanethioamide and ethyl cyanoacetate. Also, it reacts with phenyl isothiocyanate to afford the corresponding pyrazolo[3,4b]pyridin-3-yiphenylthiourea derivative 20 which in turn, used for further chemical transformations to afford com- pounds 25a,b, 29, 31 and 32. Considering the data of IR, H-1 NMR, mass spectra and chemical analyses the structures of all newly synthesized heterocyclic compounds were elucidated. Cytotoxicity, anti HSV1 and anti HAV, MBB activities were evaluated for all newly synthesized heterocyclic compounds.

Abstract  The synthesis of a new enantiopure fluorous 1,2-diaryl-1,2-diaminoethane bearing two fluorous ponytails is described. The palladium-catalyzed reaction of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate in the presence of this ligand and its analogue bearing four fluorous ponytails gave the alkylated product with ee up to 44%. Their application as ligands in hydrogen transfer reactions associated with rhodium, iridium, or ruthenium in a two-phase system gave ee up to 39%, the catalyst being recycled without loss of enantioselectivity in the case of the ruthenium complex.

Abstract  The kinetic data on the reactions of carbonylmetallates M'M(CO)(n)L(m), with polyfluorinated arenes and alkenes are reported. The behaviour of these transition metal anionic nucleophiles is compared with the reactivity of both carbanions, and non-transition metal centred anions.

Abstract  Benzothiazol-beta-amino esters, acted as beta-amino acids derivatives, perform excellent bioactivity in antibacterial and antivirus. To gain highly and purely optical single enantioisomer of benzothiazol-beta-amino esters with simple organocatalyst, recently, the development for a classic Mannich reaction of diethyl malonate (Nu) with benzothiazol imine (EI) in the presence of cinchona alkaloid derivatives as organocatalyst has been made. The study for mechanism of applying unmodified cinchona alkaloid-chiral quinidine as potent organocatalyst to asymmetric Mannich reaction of benzothiazol-beta-amino esters plays a vital role in asymmetric synthesis. In this work, the mechanism for Mannich reaction of benzothiazol-beta-amino esters catalyzed by simple chiral quinidine organocatalyst was investigated through a combination of experiment with theoretical approaches (DFT). All geometry structures of reactants (Nu and EI), intermediates and product were optimized completely with the moderate approach M06-2X/6-311G (d, p) basis set in the gas phase. Afterward, the effect of solvent for DCM was took into consideration, and CPCM was used as polarization continuum model. Frequency calculations were performed at the same level of 6-311G (d, p) basis set as the geometry optimizations to confirm stable transition state (TS), which was verified further by means of IR vibrating frequency calculations (zero and only one imaginary frequency respectively). As comparison of (R) TS pathway with (S) TS pathway in potential energy profile, it enables to elaborate that (S) TS pathway executes to afford unique enatioisomer (S). The calculating results indicate that (1) Active sites of quinidine have been confirmed, that are 9-hydroxyl and tertiary amine; (2) The product exhibits S enantiomer as major configuration; (3) Moreover, the results of DFT calculation indicated that the stereo selectivity of the reaction could be improved by lower reaction temperature. The lower temperature is, the more distereoselectivity is upgraded. The calculation demonstrated that all of results are able to be in agreement with experimental data that beta-amino acid esters derivatives carrying S as major configuration could arrive to range of 81%similar to 95% ee.

Abstract  Zeolites were incorporated as membrane and catalyst in chemical microsystems for portable energy generation and fine chemical synthesis. Microfabricated HZSM-5 micromembrane was used as a proton-exchange membrane in a miniature direct methanol fuel cell (mu-DMFC). The good proton conductivity of HZSM-5 micromembrane was attributed to a Grotthus-like diffusion of protons along the water molecules bridging neighboring aluminum sites in the hydrated HZSM-5. The 6-mu m thick HZSM-5 micromembrane exhibited comparable proton flux as Nafion(A (R)) 117 and delivered a P (max) of 2.9 mW cm(-2) (E = 0.33 V) at room temperature. This is smaller compared to 16.5 mW cm(-2) (E = 0.23 V) for a Nafion(A (R))-based mu-DMFC and was believed to be caused by adsorbed methanol molecules interrupting the proton transport along the water bridge. A Cs-exchanged NaX on NaA bilayer catalyst-membrane incorporated in microreactor channels was used for the Knoevenagel condensation reactions between benzaldehyde and (1) ethyl cyanoacetate, (2) ethyl acetoacetate (EAA) and (3) diethyl malonate. Microreactor and membrane microreactor gave higher conversion compared to fixed-bed and batch reactors, but the reaction of benzaldehyde and EAA in the microreactor had poorer selectivity due to the slow diffusion of the product molecules in the microchannel that allowed their further reactions to form undesired byproducts.

Abstract  A detailed light scattering study of polystyrene (PS) in diethyl malonate (DEM) semidilute solution has been carried out. DEM is a theta solvent for PS at 32 degrees C. Dynamic light scattering measurements carried out at temperatures closed to the theta temperature show only a diffusion mode in the intensity autocorrelation function; no slow modes are found in the semidilute PS/DEM solution with concentration up to more than 18 times the overlap concentration. For this system, the mutual diffusion coefficient is found to be mainly determined by the osmotic modulus, with the solution stress modulus making a negligible contribution. A slowing down of the mutual diffusion coefficient as the temperature approaches the critical temperature (at the critical concentration) is observed. These results show that despite considerable chain entanglements existing in the semidilute/concentrated PS/DEM solution, no viscoelastic slow modes are found. These results are not in agreement with the existing Literature data for the same system. The absence of the viscoelastic modes is interpreted as due to the fact that PS and DEM are isopycnic and the coupling of concentration fluctuations and the solution stress modulus is negligible for isopycnic polymer solutions, in accordance with a theory recently developed in this laboratory. (C) 1996 American Institute of Physics.