Three 5H‐indeno­[1,2‐c]­pyridazin‐5‐one derivatives,potent type‐B mono­amine oxidase inhibitors

The structures of three compounds, namely 7‐methoxy‐2‐[3‐(tri­fluoro­methyl)­phenyl]‐9H‐indeno­[1,2‐c]­pyridazin‐9‐one, C₁₉H₁₁F₃N₂O₂, (Id), 6‐methoxy‐2‐[3‐(tri­fluoro­methyl)­phenyl]‐9H‐indeno­[1,2‐c]­pyridazin‐9‐one, C₁₉H₁₁F₃N₂O₂, (IId), and 2‐methyl‐6‐(4,4,4‐tri­fluoro­butoxy)‐9H‐indeno­[1,2‐c]­pyridazin‐9‐one, C₁₆H₁₃F₃N₂O₂, (IIf), which are potent reversible type‐B mono­amine oxidase (MAO‐B) inhibitors, are presented and discussed. Compounds (Id) and (IId) crystallize in a nearly planar conformation. The crystal structures are stabilized by weak C—H⋯O hydrogen bonds. The packing is dominated by π–π stacking interactions between the heterocyclic central moieties of centrosymmetrically related mol­ecules. In compound (IIf), the tri­fluoro­ethyl termination is almost perpendicular to the plane of the ring.     

The effects of abstractable hydrogen in radical photopolymerization of maleate/vinyl ether monomers studied with EPR and photo‐RTIR

In this contribution, the influence of abstractable hydrogen on the kinetics of photopolymerized vinyl ether/maleate monomer formulations is reported. The effects of chain transfer on the polymerization rate were studied with photo real‐time Infra Red (IR) for formulations composed of equimolar amounts of diethyl maleate (DEMA) and three different vinyl ethers; methyl hexyl vinyl ether where the abstractable hydrogens adjacent to the vinyl functionality have been replaced with methyl groups, ethyl hexyl vinyl ether (EHVE) which has two easily abstractable α‐hydrogens and triethylene glycol methyl vinyl ether (TEGMVE), which has several abstractable hydrogens. Four conclusions are drawn from these studies: (i) the vinyl ether/maleate kinetics differs significantly from the classical expression R_p = KI^0.5, with recorded exponential factors of 0.84 ± 0.04 in the absence of easily abstractable hydrogens; (ii) the presence of abstractable hydrogens significantly changes the kinetics of vinyl ether/maleate polymerizations with recorded exponential factors of 0.55 ± 0.04 for EHVE/DEMA and 0.70 ± 0.04 for TEGMVE/DEMA; (iii) the presence of easily abstractable hydrogens leads to a preferential consumption of maleates; and (iv) electron paramagnetic resonance studies show that vinyloxy‐like radicals constitute the majority of the radicals in the systems with easily abstractable hydrogens. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2810–2816, 2010     

A beneficial kinetic effect of an η(5)-C5Me4H ligand

C-H activation of benzene at 26 °C by (η(5)-C(5)Me(5))W(NO)(CH(2)CMe(3))(η(3)-CH(2)CHCHMe) results after 4 h in the production of five new organometallic complexes, only two of which are isomers of the desired (η(5)-C(5)Me(5))W(NO)(C(6)H(5))(η(3)-CH(2)CHCHMe) compound. In contrast, the identical reaction involving the η(5)-C(5)Me(4)H analogue affords only the phenyl complexes during the first 24 h, thereby facilitating their isolation in good yields. This striking difference in reactivity can be attributed to the lesser steric demands of the η(5)-C(5)Me(4)H ligand that result in its complexes reacting at a significantly slower rate.     

Highly enantioselective organocatalytic α-amination reactions of aryl oxindoles: developing designer multifunctional alkaloid catalysts

An enantioselective α-amination of aryl oxindoles catalyzed by a dimeric quinidine has been developed. The reaction is general, broad in substrate scope, and affords the desired products in good yields with good to excellent enantioselectivities. This study provides the first examples of a general organocatalytic method for the creation of nitrogen-containing, tetrasubstituted chiral centers at C(3) of various aryl oxindoles. Furthermore, new catalysts and insights into structural elements of the catalysts that significantly influence enantioselectivities are disclosed.     

Interfacial behavior of cubic liquid crystalline nanoparticles at hydrophilic and hydrophobic surfaces

The adsorption behavior of self-assembled lipid liquid crystalline nanoparticles at different model surfaces was investigated in situ by use of ellipsometry. The technique allows time-resolved monitoring of the adsorbed amount and layer thickness under transient and steady-state conditions. The system under study was cubic-phase nanoparticle (CPNP) dispersions of glycerol monooleate stabilized by a nonionic block copolymer, Pluronic F-127. Depending on the surface properties and presence of electrolytes, different adsorption scenarios were discerned: At hydrophilic silica thick surface layers of CPNPs are generated by particle adsorption from dispersions containing added electrolyte, but no adsorption is observed in pure water. Adsorption at the hydrophobic surface involves extensive structural relaxation and formation, which is not electrolyte sensitive, of a classic monolayer structure. The different observations are rationalized in terms of differences in interactions among the CPNP aggregates, their unimer constituents, and the surface and show a strong influence of interfacial interactions on structure formation. Surface self-assembly structures with properties similar to those of the corresponding bulk aggregates appear exclusively in the weak interaction limit. This observation is in agreement with observations for surfactant self-assembly systems, and our findings indicate that this behavior is applicable also to complex self-assembly structures such as the CPNP structures discussed herein.     

Wetting phenomena at the CO2/water/glass interface

A novel high-pressure apparatus and technique were developed to measure CO2/water/solid contact angles (theta) in situ for pressures up to 204 bar. For two glass substrates with different hydrophilicities, theta increased significantly with CO2 pressure. As the pressure was increased, an increase in the cohesive energy density of CO2 caused the substrate/CO2 and water/CO2 interfacial tensions (gamma) to decrease, whereas the water/substrate gamma value increased. theta for the more hydrophobic substrate was predicted accurately from the experimental water/CO2 gamma value and an interfacial model that included only long-range forces. However, for the more hydrophilic substrate, short-range specific interactions due to capping of the silanol groups by physisorbed CO2 resulted in an unusually large increase in the water/substrate gamma value, which led to a much larger increase in theta than predicted by the model. A novel type of theta hysteresis was discovered in which larger theta values were observed during depressurization than during pressurization, even down to ambient pressure. Effective receding angles were observed upon pressurization, and effective advancing angles were observed upon depressurization on the basis of movement of the three-phase contact line. The greater degree of hysteresis for the more hydrophilic silica can be attributed in part to the capping of silanol groups with CO2. The large effects of CO2 on the various interfacial energies play a key role in the enhanced ability of CO2, relative to many organic solvents, to dry silica surfaces as reported previously on the basis of FTIR spectroscopy (Tripp, C. P.; Combes, J. R. Langmuir 1998, 14, 7348-7352).     

Attribution in Mathematics: A Review of Literature

This review of literature covers attribution studies in mathematics from 1974 through 2008. Thus far, mathematics education research in this area has been rather limited over the past few years. Attribution is discussed as it is defined by researchers, as being internal or external and its relation to mathematics achievement. In order for teachers to understand why or what is causing a student to fall behind academically, it is important that they start with attribution and whether or not it is being related to an internal or external factor. Therefore, it is imperative that new studies examine in more detail attribution from a teacher perspective and how this may impact the teaching and learning within their own classroom. This direction of the research could prove to be even more useful for preservice teachers as they begin their journey of teaching and dealing with student success and failure.     

Short, asymmetric synthesis of epi-morphine ACNO analogues

A concise and efficient asymmetric synthesis of ACNO analogues of morphine is reported.     

Versatile access to benzhydryl-phenylureas through an unexpected rearrangement during microwave-enhanced synthesis of hydantoins

[reaction: see text] A new access to benzhydryl-phenylureas is described. These new interesting urea derivatives were obtained by reaction of substituted benzils with substituted phenylureas under microwave irradiation. Phenylthiourea, when reacted with benzil, gave 3-phenyl-thiohydantoin. Moreover, benzylurea, as phenethylurea, gave the corresponding 3-substituted hydantoin derivatives, demonstrating that only phenylurea derivatives can result in benzhydryl-phenylureas under the applied conditions. This new reaction proved to be an easy access to substituted 1-benzhydryl-3-phenyl-ureas.