Cycloaddition of benzothiete and electron-deficient nitriles

The o-quinoid 8π electron system 2 , generated by thermal ring opening of benzothiete ( 1 ), enters regio-specific [8π + 2π] cycloaddition reactions with electron-deficient nitriles 3a-d , yielding the 4H-1,3-benzothiazines 4a-d. A competitive dimerization of 1 leads to 1,5-dibenzo[b,f]dithiocin (5). Depending on the nitrile further competitive or subsequent reactions (2 + 3b → 7b, 2 + 3d → 4d → 8d) can occur. The cycloadducts 10e and 11e gained from 3e anticipate a primary cleavage of 3e to methylisothiocyanate 9e which reacts at the C?N double bond as well as at the C?S double bond.     

Biphenylenes-xxxi: Condensation of benzocyclobutene-1,2-dione with aliphatic and heterocyclic 1,2-diamines and the synthesis of cis-2-cyano-3-(2'-cyanovinyl)-1,4-diaz

As possible routes to 1,4-diazabiphenylene and its 2,3-disubstituted derivatives we have studied the condensation of benzocyclobutene-1,2-dione (BBD) with various 1,2-diamines. Instead of giving the 1,4-diazabiphenylene ring system, BBD reacted with ethylenediamine, diaminomaleonitrile, 4,5-diaminopyrimidine, 2-aminopyridine, also 2,3- and 3,4-diaminopyridine to give, respectively, 2-o-carboxyphenylimidazolidinium acetate 4, 3,4-dicyano-2,5-dihydro[2,5]benzodiazocine-1,6-dione 10, 4-amino-5a,9b-dihydro-5-,9b-dihydroxybenzo [3',4']cyclobuta[1',2'-4,5]imidazo[1,2-c]pyrimidine 14, 5a,9b-dihydro-5a,9b-dihydroxybenzo[3',4']cyclobuta[1',2'-4,5] imidazo[1,2-a]pyridine 17, the 4-amino derivative 16 of the latter, and the zwitter ion 18 of 4-amino-3(2-carboxy-benzylideneamino) However, BBD reacted with 4,5-diaminobenzotriazole to give the expected 1,2,3,6,11-penta-aza-1-H-indeno [4,5-b]biphenylene 20, which, on amination followed by oxidation, gave a very low yield of cis-2-cyano-3-(2'-cyanovinyl)-1,4-diazabiphenylene 3. In model experiments, 7,8-diphenylfurazano [3,4-f]quinox-aline 28 was reduced to 2,3-diamino-5,6-diphenyl quinoxaline 29, which on oxidation, gave a mixture of cis- and trans-2-cyano-3-(2'-cyanovinyl)5,6-diphenylpyrazine, 30 and 31. The pentacyclic compounds, 1,3,6,II-tetra-aza-2-oxa-2H-indeno [4,5-b]biphenylene 23 and 1,3,5,10-tetra-aza-1-H-indeno[5,6-b] biphenylene 25, were formed from BBD and the appropriate 1,2-diamines but the 5-membered heterocyclic rings could not be cleaved by reduction and hydrolysis respectively) to give tetracyclic diamines which might have undergone oxidation to give derivatives of 1,4-diazabiphenylene. Compounds 14, 16, 20, 23, 25 and 28 are derivatives of new heterocyclic systems.     

Step-step correlations in restricted and self-avoiding random walks

Static step-step correlations for restricted and self-avoiding random walks (SARW) on quadratic and simple cubic lattices are studied with the help of Monte Carlo simulation technique. For the SARW ofN steps our results, for largeN tend to the theoretically predicted values. An analysis of the correlations for SARW in terms of the individual restrictions indicate that its value between steps at a distancer have a dominant contribution coming from the restriction prohibiting polygon closures of sides2r (r2). Our results also show that the contribution of successive restrictions to the mean-square end-to-end distance of a SARW decay with the same exponent as that of the correlations for the SARW.     

Reaction-diffusion travelling waves in the acidic nitrate-ferroin reaction

A two-variable model proposed for the acidic nitrate-ferroin reaction is considered in the reaction-diffusion context. An initial-value problem in which an amount of nitrate is introduced locally into ferroin at uniform concentration is treated both analytically and numerically. It is shown that the large time structure is a reaction-diffusion travelling wave of permanent form propagating with constant speed. This asymptotic wave speed is shown to be the minimum possible wave speed and the asymptotic approach to this value is estimated. Properties of the permanent-form travelling waves are derived and solutions valid for small and large values of a parameter , involved in the kinetic mechanism, are obtained.     

Tidal Effects in Some Regular Black Holes

This paper is aimed to study the tidal forces produced by a class of regular black holes. We consider the radial infall of test particle and find radial as well as angular components of tidal forces by taking geodesic deviation equations. We also compute geodesic deviation vector by solving geodesic deviation equation numerically. It is concluded that a particle undergos either compression or stretching in radial or angular direction due to tidal forces.     

l-Isoleucine-catalyzed Michael Synthesis of N-Alkylsuccinimide Derivatives and Their Antioxidant Activity Assessment

Russian Journal of Organic Chemistry - N-Substituted succinimides having different alkyl groups were prepared by the reaction of N-substituted maleimide with aldehydes. A two-component catalyst...     

Facile route for green synthesis of N-benzylideneaniline over bimetallic reduced graphene oxide: chemical reactivity of 2,3,4-substituted derivatives of aniline

Research on Chemical Intermediates - Mn–Co-decorated reduced graphene oxide (Mn–Co–rGO) was prepared by modified condensation method and characterized through XRD, SEM, EDX, FTIR...     

Synthesis,spectroscopic characterization,and biological activity studies of organotin(IV) derivatives of (E)‐3‐(3‐fluorophenyl)‐2‐phenyl‐2‐propenoic acid. Crystal and molecular structure of Et2Sn[OCOC(C6H5)CH(3‐FC6H4)]

The complexes Me₂SnL₂ ( I ), Me₃SnL ( II ), Et₂SnL₂ ( III ), n‐Bu₂SnL₂ ( IV ), n‐Bu₃SnL ( V ), n‐Oct₂SnL₂ ( VI ), Bz₂SnL₂ ( VII ), and Ph₃SnL ( VIII ), where “L” is ( E )‐3‐(3‐fluorophenyl)‐2‐phenyl‐2‐propenoate, have been prepared and structurally characterized by means of elemental analysis, infrared, mass, and multinuclear (¹H, ¹³C, ¹¹⁹Sn) NMR spectral techniques. The spectroscopic results showed that the geometry around the Sn atom in triorganotin(IV) derivatives is four‐coordinated in noncoordinating solvent and behaves as five‐coordinated linear polymers with bridging carboxylate groups or five‐coordinated monomers, both acquiring trans‐R₃SnO₂ geometry for Sn in the solid state. While all the diorganotin(IV) derivatives may acquire trigonal bipyramidal structures in solution due to collapse of the Sn←OCO interaction and octahedral geometries in the solid state, which have been confirmed by the X‐ray crystallographic data of the compound III . The crystal structure of Et₂SnL₂ ( III ) has been determined by X‐ray crystallography and is found skew‐trapezoidal bipyramidal, which substantiates that the ligand acts as an anisobidentate chelating agent, thus rendering the Sn atom six coordinated. The crystal is monoclinic with space group C2₁/n. All the investigated compounds have also been screened for biocidal and cytotoxicity data. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:420–432, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20243     

Correlated percolation in a film-deposition model

Clustering phenomenon has been studied in a film-deposition model in which a monolayer of particles is deposited onto a substrate. The occupation of a given site is assumed to depend on the occupation states of its nearest neighbouring sites as well as on the temperature of the particles being deposited. It is found that the percolating clusters remain ramified in that the number of their boundary sites are proportional to the number of particles in the cluster. The percolation threshold, however is lowered to (54±2)% as compared to 59% density for the uncorrelated case.     

Best proximity points: approximation and optimization

A best proximity point theorem explores the existence of an optimal approximate solution, known as a best proximity point, to the equations of the form Tx = x where T is a non-self mapping. The purpose of this article is to establish some best proximity point theorems for non-self non-expansive mappings, non-self Kannan- type mappings and non-self Chatterjea-type mappings, thereby producing optimal approximate solutions to some fixed point equations. Also, algorithms for determining such optimal approximate solutions are furnished in some cases.