Abstract  Mesoporous silica MCM-41 was successfully prepared by flow synthesis in a microreactor at shorter reaction times (i.e., minutes versus day) at high yield (i.e., 60% calcined sample) to give particles of more uniform size and shape compared to MCM-41 prepared by conventional batch synthesis. Magnetic iron oxide nanoparticles were incorporated and organic amines (i.e., propylamine and propyl diethylene amine) were grafted to obtain magnetic mesoporous catalysts for the Knoevenagel condensation reactions of benzaldehyde with ethyl cyanoacetate, ethyl acetoacetate and diethyl malonate. The incorporation of magnetic nanoparticles and large organic amines can hinder reactants access to the catalyst resulting in lower reactivity. NH2-magMCM-41 showed superb catalyst activity and selectivity for the all three Knoevenagel condensation reactions studied. The catalyst can be easily dispersed into solution and rapidly removed by a magnet for recovery and reuse. (c) 2012 Elsevier B.V. All rights reserved.

Abstract  Highly stereoselective and rapid (<1 min) addition reactions to the imine double bond of 2-(methylimino)acetate complexes [L(4)Co(O(2)CCH=NCH(3))](2+) [L(4) = (en)(2) (7), (tren) (11)] were achieved in aqueous solution with nitromethane, ethyl 3-oxobutanoate or diethyl malonate. The molecular structures of two product complexes, rac-(Δ*-R(C)*-S(N)*)-[Co(en)(2)(O(2)CCH[CH(2)NO(2)]NHCH(3))]ZnCl(4) and rac-(Δ*-R(C)*-S(N)*)-[Co(en)(2)(O(2)CCH[CH(2)COCH(3)]NHCH(3))]ZnCl(4), were established by X-ray diffraction.

Abstract  1. Exogenous glycollate was rapidly metabolized in both the light and the dark by photoautotrophically grown Chlorella pyrenoidosa. 2. The incorporation of (14)C from [1-(14)C]glycollate by these cells was inhibited by the tricarboxylic acid-cycle inhibitors monofluoroacetate, diethylmalonate and arsenite, and also by alpha-hydroxypyrid-2-ylmethanesulphonate and isonicotinylhydrazine. 3. Short-term kinetic experiments showed over 80% of the total (14)C present in the soluble fraction from the cells to be in glycine and serine after 10s. This percentage decreased with time whereas the percentage radioactivity in glycerate increased for up to 30s then remained steady. The percentage of the total radioactivity present in citrate increased over the experimental period. Malate was the only other tricarboxylic acid-cycle intermediate to become labelled. 4. The kinetic and inhibitor experiments supported the following pathway of glycollate incorporation: glycollate --> glyoxylate --> glycine --> serine --> hydroxypyruvate --> glycerate --> 3-phosphoglycerate --> 2-phosphoglycerate --> phosphoenolpyruvate --> pyruvate --> acetyl-CoA. 5. The specific activities of the enzymes catalysing this metabolic sequence in cell-free extracts were great enough to account for the observed rate of glycollate metabolism of 0.25mumol/h per mg dry wt. of cells in the light.

Abstract  A convergent, stereocontrolled construction of the cis,anti,cis-tricyclo[5.3.0.0(2,6)]decane nucleus of spatane diterpenes was achieved by 2-pi + 2-pi photocycloaddition of 2-cyclopenten-1-one, as an A-ring precursor, with a carbonyl-masked derivative of 6-methylbicyclo[2.2.1]hept-5-en-2-one as a temporarily bridged C-ring precursor. By design, the temporary bridge assures the correct stereochemical relationship between the B-ring stereocenters and the C-ring hydroxyl substituent that is present in latent form in the oxoethano bridge. Serendipitously, the bridge also fosters a favorable orientation of the photocycloaddition that contrasts with the nonselective 2-pi + 2-pi-photocycloadditions of unbridged 1-methylcyclopentenes with 2-cyclopenten-1-one. Wittig methylenation of the A-ring carbonyl in photoproduct 24 followed by hydrolysis to 25 and catalytic hydrogenation introduces a methyl group at position 1 with a 10:1 preference for the requisite stereochemistry in 26. Even higher stereoselectivity was achieved by SO2-promoted isomerization of the exocyclic C=C bond in 25 to an endocyclic disposition in 29 prior to catalytic hydrogenation. Johnson's sulfoximine method is especially effective for resolution of ketone 29. The oxoethano bridge in ketone 26n is oxidized rapidly but nonregioselectively by an H2SO4-catalyzed reaction with peracetic acid, producing a 57:43 mixture of 14 and 34. Regioselective generation of the desired lactone 14 could be accomplished by a much slower oxidation with peracetic acid and no added H2SO4. The necessary configuration at position 7 in 49 was generated stereoselectively by a novel homoallylic hydroxyl-directed, pseudointramolecular delivery of hydride to the methylenemalonic ester in the precursor 48. Conversion of the malonic ester moiety in 49 into an allylic alcohol was accomplished in 92% overall yield by monosaponification, decarboxylative condensation with formaldehyde and reduction of the resulting acrylic ester with i-Bu2AlH. Selective oxidation of the allylic hydroxyl followed by acetylation delivered acetate (+)-11a, which is identical with an oxidative degradation product from spatane diterpenes.

Abstract  Regioselective nucleophilic addition of bisnucleophiles 1,2-benzenediamine, 2-amino-benzenethiol, and N-phenyl-1,2-benzenediamine to 1,3-diphenylbenzo[e][1,2,4]triazin-7(1H)-one (1) at C6 followed by intramolecular cyclocondensation at the C7 carbonyl afforded highly coloured tetracenes 1,3-diphenyl-1,6-dihydro-[1,2,4]triazino[5,6-b]phenazin-4-ium 4-methylbenzenesulfonate (12), 1,3-diphenyl-1H-[1,2,4]triazino[6,5-b]phenothiazine (14) and 1,3,11-triphenyl-1,6-dihydro-[1,2,4]triazino[5,6-b]phenazin-11-ium 4-methylbenzenesulfonate (15), respectively. Neutralization of the latter with alkali gave the free base 1,3,11-triphenyl-1H-[1,2,4]triazino[5,6-b]phenazin-11-ium-6-ide (16). Furthermore, the benzotriazinone 1 reacts with dimethyl malonate to give 6-(methoxycarbonyl)-7-oxo-1,3-diphenyl-7H-benzofuro[5,6-e][1,2,4]triazin-1-ium-4-ide (17) in 74% yield, while with S(4)N(4) [5,6-c]-thiadiazolo-7-oxo-1,3-diphenyl-1,2,4-benzotriazine (22) was formed in 15% yield. The free bases 16 and 17 display negative solvatochromism, which supports charge separated ground states similar to those of zwitterionic biscyanines, and DFT calculations at the UB3LYP/6-31G(d) level afford ΔE(ST) values of -13.6 and -18.7 kcal mol(-1), respectively that strongly favour the singlet ground state. All ring systems described are new and fully characterized.

Abstract  The complexation of lanthanides (Ln) with dicarbonyl compounds (acetylacetone, acac; ethyl acetoacetate; 3-ethyl-2,4-pentanedione; 2,4-hexanedione; 3-methyl-2,4-pentanedione; and diethyl malonate) was investigated using a potentiometric titration technique. The ability of a dicarbonyl compound to complex with the lanthanide elements was greatly dependent on its pK(a) and on the pH of the titrated solution. Selected lanthanide complexes (Ln complexes) were incorporated into spherical poly(L-lactic acid) (PLA) matrices and irradiated in a nuclear reactor with neutrons to produce short-lived high-energy beta-particle-emitting radioisotopes. The lanthanides investigated (Ho, Dy, Sm, and La) were chosen on the basis of their physical and nuclear properties. A transition element (Re) was also studied. The small decrease in the ionic radii of the lanthanides with increasing atomic number led to (a) greater ability to extract and complex from an aqueous solution with complexing agents, (b) larger formation and stability constants for the Ln complexes, (c) increased solubility of the Ln complexes in chloroform, and (d) increase in the maximum percent incorporation of the stable lanthanides in PLA spheres. Ho(acaC)3 was found to be the most promising candidate of the complexes studied on the basis of the above observations and due to the favorable physical properties of Ho-165 and nuclear properties of Ho-166.

Abstract  The measurement of matrix metalloproteinase (MMP) activity in diseases like inflammation, oncogenesis, or atherosclerosis in vivo is highly desirable. Fine-tuned pyrimidine-2,4,6-triones (barbiturates) offer nonpeptidyl lead structures for developing imaging agents for specifically visualization of activated MMPs in vivo. The aim of this study was to modify a C-5-disubstituted barbiturate and thus design a highly affine, nonpeptidic, optical MMP inhibitor (MMPI)-ligand for imaging of activated MMPs in vivo. A convergent 10 step synthesis was developed, starting with a malonic ester and (4-bromophenoxy)benzene to generate 5-bromo-pyrimidine-2,4,6-trione as the key intermediate. To minimize the interactions between activated MMPs and the dye of the conjugate 6, a PEGylated piperazine derivative was used as a spacer and an azide as a protected amino function. After linking both building blocks, reducing the azide ( Staudinger reaction) and labeling with Cy 5.5, we obtained the nonhydroxamate MMP inhibitor 6 with high affinity (IC 50-value: 48 nM for MMP-2) measured in a fluorogenic assay using commercially available MMP-substrates and the purified enzyme. Zymography revealed an efficient blocking of enzyme activity of purified MMP-2 and MMP-9 and of MMP-containing cell supernatants (HT-1080), (A-673) using the PEGylated barbiturate 5. Fluorescence microscopy studies using a highly (A-673) and a moderate (HT-1080) MMP-2 secreting cell line showed efficient binding of the Cy 5.5 labeled tracer 6 to the MMP-2 positive cells while MMP-2 negative cells (MCF-7) did not bind. Therefore, this new barbiturate-based MMP-probe has a high affinity and specificity toward MMP-2 and -9 and is thus a promising candidate for sensitive MMP detection in vivo.

Abstract  We report that a subtoxic dose of the succinate dehydrogenase (SDH) inhibitor malonate greatly enhances the neurotoxicity of three different excitatory amino acid agonists: N-methyl-D-aspartate (NMDA), S-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (S-AMPA), and L-glutamate. In male Sprague-Dawley rats, intrastriatal stereotaxic injection of malonate alone (0.6 mumol), NMDA alone (15 nmol), S-AMPA alone (1 nmol), or glutamate alone (0.6 mumol) produced negligible toxicity as assessed by measurement of lesion volume. Coinjection of subtoxic malonate with NMDA produced a large lesion (15.2 +/- 1.4 mm3), as did coinjection of malonate with S-AMPA (11.0 +/- 1.0 mm3) or glutamate (12.8 +/- 0.7 mm3). Administration of the noncompetitive NMDA antagonist MK-801 (5 mg/kg i.p.) completely blocked the toxicity of malonate plus NMDA (0.5 +/- 0.3 mm3). This dose of MK-801 had little effect on the lesion produced by malonate plus S-AMPA (9.0 +/- 0.7 mm3), but it attenuated the toxicity of malonate plus glutamate by approximately 40% (7.5 +/- 0.9 mm3). Coinjection of the AMPA antagonist 2,3-dihydroxy-6-nitro-7-sulfamoylbenzo(f)-quinoxaline (NBQX; 2 nmol) had no effect on malonate plus NMDA or malonate plus glutamate toxicity (12.3 +/- 1.8 and 14.0 +/- 0.9 mm3, respectively) but greatly attenuated malonate plus S-AMPA toxicity (1.5 +/- 0.9 mm3). Combination of the two antagonists conferred no additional neuroprotection in any paradigm. These results indicate that metabolic inhibition exacerbates both NMDA receptor- and non-NMDA receptor-mediated excitotoxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Abstract  In this work, voltammetric, spectroelectrochemical, and electrocatalytic properties of the metallophthalocyanines bearing four chloro and four biphenyl-malonic ester bulky groups were investigated. Voltammetric and spectroelectrochemical measurements of the metallophthalocyanines show that while cobalt phthalocyanine presents both metal-based and ring-based redox processes, all other complexes give only ring-based reduction and oxidation processes. The redox processes have generally diffusion-controlled, reversible and one-electron transferred mechanisms. Cobalt phthalocyanine electrocoated easily on the glassy carbon working electrode during the repeating cycles, a very useful feature for application in fabrication of thin films. Electrocatalytic activity of cobalt phthalocyanine to hydrogen evolution reaction was studied in solution titrated with perchloric acid and on glassy carbon electrode modified with cobalt phthalocyanine in aqueous solution. Electrocatalytic measurements show that cobalt phthalocyanine has significant catalytic activities towards hydrogen evolution reaction. Moreover, the catalytic activity of the complex enhanced significantly when the complex was incorporated into the cation exchange Nafion polymeric matrix.

Abstract  The chemistry of chiral ligands for transition metal-catalyzed asymmetric reactions is an interesting research field in synthetic chemistry and has recently been the focus of much attention. Although a number of chiral ligands containing phosphorus (P) and arsenic (As) have been widely studied and are well documented, asymmetric reactions with optically active organoantimony compounds have not been reported so far. We are interested in the synthesis and utilization of optically active organoantimony compounds for asymmetric synthesis. We present here the synthesis and resolution of Sb-chiral and C2-symmetric compounds containing antimony as well as their physical and chemical properties. Resolution of (+/-)-1-phenyl-2-trimetylsilylstibindole (1), Sb (R/S)-(aryl) [2-(S)-(1-dimethylaminoethyl) phenyl] (p-tolyl) stibane (9), and (+/-)-2,2'-bis(diarylstibano)-1,1'-binaphthyl (13) can be achieved by the separation of a mixture of the diastereomeric antimony-palladium complexes. The optically pure Sb-chiral stibanes (1, 9) isolated here were optically stable, and no racemization on the chiral antimony center was observed even when they were heated under a neutral or a basic condition. Single-crystal X-ray analysis of Sb-chiral triarylstibane 9b-B revealed the presence of an intramolecular interaction between the antimony and nitrogen atoms. The optically active BINASb (13) can be used as powerful chiral ligand for the palladium-catalyzed asymmetric allylic alkylation of racemic 1,3-diphenyl-2-propen-1-yl acetate with dimethyl malonate. We also report the synthesis, molecular structure, and fluxional behavior of the (R)-(-)-7-p-tolyl-dinaphtho [2, 1-b; 1',2'-d] stibole (21c) which is the first isolated example of optically active C2-symmetric group 15 dinaphthoheteroles.

Abstract  The production and use pattern of Diethylmalonate (DEM) and Dimethylmalonate (DMM) are comparable. The two chemicals have very similar physico-chemical properties and both esters are hydrolyzed via a two step reaction to malonic acid and the corresponding alcohol, methanol or ethanol. It is likely that unspecific esterases in the body catalyze the hydrolysis. The alcohols and malonic acid are physiological substances that are metabolized via physiological pathways. Ethanol (CAS No. 64-17-5) and methanol (CAS No. 67-56-1) were assessed at SIAM 19. For ethanol it was concluded that the chemical is currently of low priority for further work, because the hazardous properties of ethanol are manifest only at doses associated with consumption of alcoholic beverages. As it is impossible to reach these exposure levels as a consequence of the manufacture and use of malonates, it can be expected that malonic acid will be the metabolite that determines the toxicity of DEM. For methanol, SIAM 19 decided that this chemical is a candidate for further work. Methanol exhibits potential hazardous properties for human health (neurological effects, CNS depression, ocular effects, reproductive and developmental effects, and other organ toxicity). The effects of methanol on the CNS and retina in humans only occur at doses at which formate accumulates due to a rate-limiting conversion to carbon dioxide. In primates, formate accumulation was observed at methanol doses greater than 500 mg/kg bw (which would require a DMM dose of more than 1000 mg/kg bw). As there were no indications of a methanol associated toxicity from a well performed repeated dose toxicity study with DMM in rodents (which are, however, known to be less sensitive to methanol toxicity than humans), and because methanol toxicity would not be expected up to doses as high as 1000 mg DMM/kg bw/day, it was concluded that methanol does not make a relevant contribution to the toxicity profile of DMM. A possible mode of action for systemic toxicity of DMM and DEM can only be deduced from the repeated dose study with DMM, indicating a reversible liver hypertrophy at the cellular level at high doses of 1000 mg/kg bw/day. This effect can be an indication of an induction of metabolism in the liver rather than a clear systemic toxicity.

Abstract  Nine alpha-dibutylaminomethylbenzo[h]quinoline-4-methanols were synthesized from the corresponding 1-amino-naphthalenes by the following sequence: 1-aminonaphthalene leads to 1H-benz[g]indole-2,3-dione leads to benzo[h]quinoline-4-carboxylic acid leads to acid chloride leads to bromomethyl ketone leads to epoxide leads to benzo[h]quinoline-4-methanol. Several acid chlorides substituted in the 3 position reacted incompletely with ethereal diazomethane but were efficiently converted, without isolation of the intermediates, to the bromomethyl ketones by reaction with ethoxymagnesium diethylmalonate, bromination, hydrolysis, and decarboxylation. Several compounds prepared, especially alpha-dibutylaminomethyl-2-(2',4'-dimethylphenyl)-3-methyl-6-chlorobenzo[h]quinoline-4-methanol, showed significant antimalarial activity against Plasmodium berghei in infected mice but were moderately phototoxic.

Abstract  For the functional enhancement of chelating resins containing carboxylic acids, copolymer beads were prepared by suspension polymerization of styrene (St), methyl methacrylate (MMA), and divinylbenzene (DVB) in the presence of toluene as diluent. The phenyl rings of the beads were directly chloromethylated, and the carboxylic ester groups of the beads were converted into hydroxymethyl groups by reduction followed by chlorination to give chloromethyl groups, respectively. The chelating resins containing a pair of neighboring carboxylic acid groups (NCAGs) were obtained by the alkylation of chloromethyl groups in copolymer beads with diethyl malonate in the presence of sodium hydride followed by hydrolysis using aqueous alkali solution. Accordingly, the structural effects of the resins on the adsorption of heavy metal ions were investigated. Poly(St- co -DVB)-based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Pb 2+ , Cd 2+ , and Cu 2+ , whereas poly(MMA- co -DVB)-based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Cu 2+ , Cd 2+ , and Co 2+ . On the other hand, poly(St- co -MMA- co -DVB)-based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Pb 2+ , Cd 2+ , Hg 2+ , Co 2+ , and Cu 2+ : a synergistic effect on the adsorption of heavy metal ions like Pb 2+ , Cd 2+ , Hg 2+ , and Co 2+ was observed. The adsorption ability of poly(St- co -MMA- co -DVB)-based chelating resin among three kinds of chelating resins was relatively good.

Abstract  Fullerenes could potentially play a valuable role in radioimmunotherapy by more stably encapsulating radionuclides, especially where conventional chelation chemistry is inadequate due to the physical and/or chemical properties of the radionuclide. One of the therapeutically useful radionuclides that requires improved containment in vivo is Pb-212 (tau(1/2) = 10.6 h), the beta-emitting parent to alpha-emitting Bi-212 (tau(1/2) = 60.6 min). Myelotoxicity resulting from the accumulation of Pb-212 in the bone marrow has limited the use of this radionuclide despite its favorable decay characteristics. In this work, Pb-212@C-60 and its malonic ester derivatives were prepared for the first time by allowing the Pb-212 to recoil into C-60 following alpha-decay from its parent, 0.15-s Po-216, generated in situ from the decay of Ra-224 (tau(1/2) = 15 days). Repeated washing of the organic phase containing the Pb-212@C-60 malonic esters with challenge solutions containing cold Pb2+ ions demonstrated that some of the Pb-212 could not be exchanged and was apparently inside of the fullerenes. Malonic esters of endohedral alpha-emitting Bi-213 (tau(1/2) = 45 min) fullerenes were prepared by an analogous procedure. Following acidification of the esters, a preliminary biodistribution study in mice was performed with the untargeted water-soluble radiofullerenes. It was found that Pb-212 did not accumulate in bone after being administered as an endohedral fullerene, in contrast to results with polyhydroxylated radiofullerenes and conventional polyaminocarboxylate chelators for Pb-212. The results indicate that Pb-212 is held more tightly in the fullerene than in other methods and suggest that fullerenes may have an important role in the targeted delivery of Pb-212.

Abstract  We describe a brass light pipe (LP) mounted in a cylindrical optical accessory for attenuated total reflection (ATR) that can be used to readily obtain the infrared spectra of liquids and monolayers. As examples, we show the LP spectra of isooctane, decane, dimethyl malonate, dodecanol, dodecanethiol, and acetic acid and compare them to those obtained by transmission as well as by ATR. In addition, we utilize a dodecanethiol monolayer spectrum to illustrate the sensitivity of the LP scheme.

Abstract  A novel approach to stereo controlled synthesis of cis-anti-cis fused triquinane is reported from readily accessible starting material, endo-tricyclo[5.2.1.0 super(2,6)]deca-4,8-dien-4-bromo-3-one using Michael addition and radical cyclization reactions as key steps.

Abstract    Ethyl 4-bromo (and chloro)-3-oxobutanoate (1 and 2) reacts with diethyl malonate in the presence of sodium hydride to give diethyl 5-ethoxycarbonyl-3-oxohexanedioate (3) and diethyl 5-carboxy-3-oxohexanedioate (4). Similarly, reaction of the haloester (1, 2) with methyl cyanoacetate gives 1-ethyl methyl 5-cyano-3-oxohexanedioate (6) and 1-ethyl hydrogen 5-cyano-3-oxohexanedioate (7). On the other hand, 1 reacts with malononitrile in the presence of triethylamine to give ethyl 5-amino-4-cyanofuran-2-acetate (8) and ethyl 3-amino-2, 4, 4-tricyano-2-cyclopenten-1-ylideneacetate (9).

Abstract  The biosynthesis of 5-hydroxy-4-oxo-L-norvaline (HON) in Streptomyces akiyoshiensis has been investigated using super(13)C-labelled substrates. Incorporations of super(13)C label from sodium [1- super(13)C]-, [2- super(13)C]-, and [1,2- super(13)C sub(2)]acetate indicated that HON was formed from a four-carbon compound derived from the citric acid cycle and the methyl carbon of acetate. Feeding experiments using DL-[4- super(13)C]- and DL-[2- super(13)C, super(15)N]aspartate demonstrated that aspartate served as the four-carbon precursor to HON. Both enantiomers of aspartate were metabolized by S. akiyoshiensis, but the D isomer was consumed at a slower rate. The distribution of super(13)C label in the intracellular L-glutamic acid isolated in these feeding experiments is consistent with the operation of the citric acid cycle in S. akiyoshiensis. A biosynthetic hypothesis that involves a condensation reaction between acetyl or malonyl CoA and the beta -carboxyl group of aspartate, and subsequent oxidative decarboxylation, is proposed to account for the incorporation results. An analogous condensation step has been proposed for the biosynthesis of other natural products, including the carbapenem antibiotics. DL-[2- super(13)C, super(15)N]Aspartate was synthesized from [2- super(13)C]diethylmalonate and potassium [ super(15)N]phthalimide via diethyl [2- super(13)C, super(15)N]phthalimidomalonate.

Abstract    Veratraldehyde was condensed with methyl 2-chloropropanoate to give a glycidic ester. This was hydrolyzed with aqueous sodium hydroxide and the resulting sodium salt was treated with lead(IV) tetraacetate to give 1-acetoxy-1-(3, 4-dimethoxyphenyl)propan-2-one (13). Condensation of 13 with dimethyl malonate, followed by acidic hydrolysis and sodium borohydride reduction afforded (2R*, 3S*, 4R*)-4-(3, 4-dimethoxyphenyl)-2-methoxycarbonyl-3-methyl-4-butanolide (7a). The γ-lactone 7a was then converted into 5'-demethoxyporosin (10) by means of a series of reactions : Michael reaction with methyl vinyl ketone, elimination of the methoxycarbonyl group, acetalization, allylation, deacetalization, and intramolecular aldol reaction. Introduction of a hydroxyl group at the C-5' position in 10, followed by methylation with diazomethane afforded racemic porosin. The synthetic porosin was further converted into 5-demethoxymegaphone acetate.

Abstract  Hybrid polar compounds, of which hexamethylenebisacetamide (HMBA) is the prototype, are potent inducers of differentiation of murine erythroleukemia (MEL) cells and a wide variety of other transformed cells. HMBA has been shown to induce differentiation of neoplastic cells in patients, but is not an adequate therapeutic agent because of dose-limiting toxicity. We report on a group of three potent second generation hybrid polar compounds, diethyl bis-(pentamethylene-N,N-dimethylcarboxamide) malonate (EMBA), suberoylanilide hydroxamic acid (SAHA), and m-carboxycinnamic acid bis-hydroxamide (CBHA) with optimal concentrations for inducing MEL cells of 0.4 mM, 2 microM, and 4 microM, respectively, compared to 5 mM for HMBA. All three agents induce accumulation of underphosphorylated pRB; increased levels of p2l protein, a prolongation of the initial G1 phase of the cell cycle; and accumulation of hemoglobin. However, based upon their effective concentrations, the cross-resistance or sensitivity of an HMBA-resistant MEL cell variant, and differences in c-myb expression during induction, these differentiation-inducing hybrid polar compounds can be grouped into two subsets, HMBA/EMBA and SAHA/CBHA. This classification may prove of value in selecting and planning prospective preclinical and clinical studies toward the treatment of cancer by differentiation therapy.

Abstract    The experiments of immiscible liquid-liquid mixing in a stirred vessel were performed in order to relate the drop size distribution with impeller revolutional speed and to examine the applicability of a new formula of the drop size distribution presented by authors. The new formula based on an information entropy concept is composed of the product of the original distribution function and the realizable probability function derived under following two assumptions. First, the break-up of a drop occurs when the external force/energy exceeds the internal force/energy of the drop. Second, there is a limitation in the drop size which can exist in actuality. In the present work, ethyl malonate and water were adopted as a dispersed phase and a continuous phase, respectively. By setting the dilute volume fraction of the dispersed phase, the break-up of drops seems to be dominant while coalescence could be negligible. Impeller revolutional speed was varied from 210 to 300 rpm. A photographic method was utilized to measure the drop size. It is clarified that the new formula can express sufficiently the experimental data. Additionally, the drop size distribution for the number density derived from the new formula is also in agreement with the experimental data. The usefulness of the newly expressed formula is confirmed by applying it to other experimental data presented by other investigators. The parameter L as a mean size in the new formula is correlated with the impeller revolutional speed and it is made clear that L is in proportion to the impeller revolutional speed to the minus 1.2 power like the case of the Sauter mean drop size and the maximum drop size. The other parameter B as a coefficient is considered to be affected only by the ratio of the viscosity of dispersed phase to that of continuous phase of the liquid-liquid system.

Abstract    Novel arene-ruthenium [2+2] metalla-rectangles 4 and 5 have been synthesized by self-assembly using dipyridyl amide ligand 3 and arene-ruthenium acceptors (arene: benzoquinone (1), naphthacenedione (2)) and characterized by NMR spectroscopy and ESI-MS. The solid-state structure of 5 was determined by X-ray diffraction and shows encapsulated diethyl ether molecule in the rectangular cavity of 5. The luminescent 5 was further used for anion sensing with the amidic linkage serving as a hydrogen-bond donor site for anions and the ruthenium moiety serving as a signaling unit. A UV/Vis titration study demonstrated that although 5 interacts very weakly with common monoanions as well as with flexible dicarboxylate anions such as malonate and succinate, it displays significant binding affinity (K>103 in MeOH) for rigid multi-carboxylate anions such as oxalate, citrate, and tartrate, exhibiting a 1:1 stoichiometry. It has been suggested that 1:1 bidentate hydrogen bonding assisted by appropriate geometrical complementarity is mainly responsible for the increased affinity of 5 towards such anions. A fluorescence titration study revealed a large fluorescence enhancement of 5 upon binding to multi-carboxylate anions, which can be attributed to the blocking of the photoinduced electron-transfer process from the arene-Ru moiety to the amidic donor in 5 as a result of hydrogen bonding between the donor and the anion.

Abstract  Enantioselective Pd-catalyzed allylic substitution of ()-()-1,3-diphenyl-3-acetoxyprop-1-ene with dimethyl malonate was studied in 3-butyl-1-methylimidazolium hexafluorophosphate ([bmim][PF]) as an ionic liquid. The reactions were catalyzed by Pd() complexes of three homochiral ferrocenylphosphine ligands, (,)-iPr-Phosferrox, (,)-iPr-Phosferrox, (,)-BCyPFA and ()-BINAP. Potassium carbonate and bis(trimethylsilyl)acetamide (BSA)/AcOK were tested as the bases and simple optimization of the reaction procedure was performed. Experiments with other soft nucleophiles also were carried out under optimized conditions.

Abstract  Enantioselective allylic substitution reactions of ()-()-1,3-diphenyl-3-acetoxyprop-1-ene with dimethyl malonate (DMM) are studied in 1-butyl-3-methylimidazolinium hexafluorophosphate ([bmim][PF]) as an ionic solvent; the reactions are catalyzed by Pd complexes of two homochiral ferrocenylphosphine ligands, ()-BPPFA and ()-BPPFDEA with the recycling of the catalytic system being tested. A similar reaction with 1-phenyl-3-acetoxyprop-1-ene is also studied with only a linear achiral product being isolated.