Michael reaction of indoles with 3-(2′-nitrovinyl)indole under solvent-free conditions and in solution. An efficient synthesis of 2,2-bis(indolyl)nitroethanes and studies on their reduction

Michael reaction of 3-(2′-nitrovinyl)indole with eight 3-unsubstituted indoles on TLC-grade silica gel furnished unsymmetrical bis(indolyl)nitroethanes in 7-12 min under microwave irradiation and in 8-14 h at rt. In contrast, the p-TsOH-catalysed reaction of the nitrovinylindole with the 3-unsubstituted and two 3-substituted indoles in solution under reflux furnished both unsymmetrical and symmetrical bis(indolyl)nitroethanes, the latter resulting from novel tandem Michael addition-elimination-Michael addition reactions. The synthesis of a 2′,3″-bis(indolyl)nitroethane, the precursor core structure of two bioactive marine metabolites, and the reduction of 2,2-bis(3′-indolyl)nitroethane to the corresponding ethylamine, isolated as its N-acetyl derivative, have been achieved. Significantly, attempted hydrolysis of three nitronates, derived from the corresponding bis(indolyl)nitroethanes, with buffered aqueous TiCl₃ has led to the first isolation of oximes (syn/anti-mixture) as the only products.     

Synthesis of polyurethane from cashew nut shell liquid (CNSL), a renewable resource

A novel thermoplastic polyurethane was prepared from cardanol, a renewable resource and a waste of the cashew industry. Cardanol was recovered from cashew nut shell liquid (CNSL) by double vacuum distillation. It was characterized by CHN analysis and IR, ¹H-NMR, and ¹³C-NMR spectroscopy techniques. Cardanol is a meta-substituted long chain phenol. The long aliphatic chain unit substituent was found to be a monoene. The monomer, 4-[(4-hydroxy-2-pentadecenylphenyl)diazenyl]phenol was prepared from cardanol. It was a dihydroxy compound as characterized by CHN analyzer, UV, and ¹H-NMR spectroscopy. The polyurethane was synthesized from this dihydroxy compound by the treatment with 4,4′-diphenylmethane diisocyanate (MDI) in dimethylformamide (DMF) solvent at 80–90°C under nitrogen atmosphere. The polymer was characterized by ¹H-NMR, FTIR, and UV spectroscopy. The elemental analysis was done for determining the percentage content of C, H, and N, and the intrinsic viscosity [η] of polymer showed 1.85 dL/gm. Thermogravimetric investigations (TGA) of the cardanol, the dihydroxy compound, and the polyurethane were performed to study their decomposition. The semicrystalline nature of the PU was confirmed by differential scanning calorimetry (DSC) and dynamic mechanical thermal analyzer (DMTA). The wide-angle X-ray diffraction (WAXS) study of PU shew a broad amorphous halo indicative of absence of crystallinity in the polymer, which has been explained as due to strong hydrogen bonding in the hard phase. PU may possibly be useful as a telecommunication and as a nonlinear optical material. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36 : 391–400, 1998     

Quantitative molecular similarity analysis (QMSA) methods for property estimation: A comparison of property-based,arbitrary, and tailored similarity spaces

Three classes of arbitrary quantitative molecular similarity analysis (QMSA) methods have been computed using atom pairs, topological indices, and physicochemical properties. Tailored QMSA models have been developed using a selected number of TIs chosen by ridge regression. The methods have been applied to the K -nearest neighbor based estimation of log P of two sets of chemicals. Results show that the property-based and tailored QMSA methods are superior to the arbitrary similarity methods in estimating log P of both sets of chemicals     

Anhydrous proton conductivities of squaric acid derivatives

In this communication, we introduce squaric acid derivatives as anhydrous proton conductors. We report the synthesis, characterization and proton conductivities of four squaric acid derivatives. The anhydrous proton conductivity of one of the derivatives was 2.3 × 10(-3) S cm(-1) at 110 °C, comparable to the conductivity of molten 1H-1,2,3-triazole or 1H-imidazole.     

Titanium catalyzed one-pot multicomponent coupling reactions for direct access to substituted pyrimidines

A titanium-catalyzed 3-component coupling reaction can be used to generate tautomers of 1,3-diimines. These diimines produced in situ undergo condensation with amidines in a one-pot procedure to provide substituted pyrimidines. Seventeen examples of pyrimidines are provided using this one-pot, 4-component procedure from simple starting materials. In some cases, catalyst architecture can be tuned to control the regioselectivity of the alkyne addition. Finally, the regioselectivity of amidine addition to unsymmetrical 1,3-diimines is discussed.     

A comparative study of proteomics maps using graph theoretical biodescriptors

This paper reports the development of new methods for mathematical characterization of effects of different toxic agents on the cellular proteome. We describe numerical characterization of proteomics maps based on mathematical invariants. A graph is first associated with a proteomics map by considering partial ordering of spots on 2-D gels by ordering proteins with respect to the mass and the charge, the two properties by which proteins are separated. The graph is then embedded over the map, and several graph theoretical invariants have been constructed. In particular we consider invariants that can be extracted from the Euclidean distance-adjacency matrix of the embedded graph, in which only Euclidean distances between adjacent vertices of a graph are considered. The approach is illustrated using proteomics patterns of normal liver cells of rats and those derived from liver cells of animals exposed to four peroxisome proliferators. In contrast to direct comparison of spot abundance our approach incorporates information on spots locations. The difference between the two approaches is that in the first case only changes in abundances are considered as a measure of perturbation of the proteome map, but in the second case not only the charge but also the mass of proteins are used for ordering protein spots.     

The thermoelectric power of the metallic glass Ca0.8Al0.2

We report the first measurement of the thermoelectric power Q, of a metallic glass that contains only normal metals. The thermoelectric power of amorphous Ca_0.8Al_0.2 has been measured as a function of temperature from 10 K to 420 K. It is found that Q is positive, varies linearly with temperature and has a small slope. This is similar to the thermoelectric power found for other metallic glasses containing large concentrations of transition metal atoms.     

Separation of variables and explicit theta-function solution of the classical Steklov-Lyapunov systems: A geometric and algebraic geometric background

The paper revises the explicit integration of the classical Steklov-Lyapunov systems via separation of variables, which had been first made by F. Kötter in 1900, but was not well understood until recently. We give a geometric interpretation of the separating variables and then, applying the Weierstrass hyperelliptic root functions, obtain explicit theta-function solution to the problem. We also analyze the structure of poles of the solution on the Jacobian on the corresponding hyperelliptic curve. This enables us to obtain a solution for an alternative set of phase variables of the systems that has a specific compact form. In conclusion we discuss the problem of integration of the Rubanovsky gyroscopic generalizations of the above systems.     

Simple and convenient one-pot synthesis of cyclooctatetraene

Cyclooctatetraene is readily synthesized by the oxidation of in situ generated [Li(TMEDA)]₂[C₈H₈] with 1,2-dibromoethane. The product is readily isolated and produced without the use of hazardous or toxic reagents.