Novel chain and ring polyphosphorus compounds

Abstract

Compounds with a skeleton of phosphorus chains or rings have been rare until recently, as they are in general highly reactive. Nevertheless, considerable progress has been achieved in this field lately, especially regarding three-membered phosphorus ring compounds, metalated phosphorus hydrides and polycyclic organophosphanes.     

RCM for the construction of novel steroid-like polycyclic systems. 1. Studies on the synthesis of a PreD3-D3 transition state analogue

Natural and nonnatural polycyclic systems containing eight-membered carbocycles constitute a large class of compounds of importance in organic chemistry, biology, and medicine. Here we describe a new strategy by which complex polycyclic steroid-like systems can be constructed on the steroid CD framework, by a combination of RCM and Heck cyclizations. The method is exemplified by its application to the stereoselective synthesis of 6-8-6 fused carbocyclic systems that mimic the putative transition structure of the isomerization of previtamin D3 to vitamin D3.     

Heterocyclic Synthesis With Nitriles: Synthesis Of Some New Chromone and Flavone and Its Utilization For The Synthesis Of Potentially Antitumorigenic Polycyclic Chromones and Flavones

A new synthesis of chromones and flavones based on the reaction of 2-hydroxy-1-acetonaphthone (1) with cinammonitriles (2 a-h) is described. Structures of the compounds are established by chemical and spectral data. This synthetic approach appears general in its applicability. It has been applied to the synthesis of a series of polycyclic chromone and flavone compounds containing the naphthalene and pyrene ring systems that hold promise as agents for the chemo preventation of cancer.     

Automatic estimation of ring strain energies

A simple model has been developed which allows to estimate ring strain energies of monocyclic and bicyclic compounds. It can also be applied to polycyclic systems with reasonable accuracy. A computer program based on this model has been implemented which relies on a topological representation of molecular structures and performs the estimation of the effects of ring strain both on molecular energies and on reaction enthalpies.     

First synthesis of new polycyclic systems from ortho-di(heteroaryl)-substituted furazanopyrazine derivatives by the Scholl reaction

A facile synthetic protocol to hard-to-get polycyclic (hetero)-aromatic compounds annulated to [1,2,4]oxadiazolo[3,4-b]-pyrazine scaffold via the FeCl₃-mediated intramolecular Scholl cross-coupling has been developed. Based on the electrochemical and photophysical measurements, the synthesized polycyclic systems may be regarded as narrow band-gap (from 1.42 to 1.89 eV) n-type organic semiconductors whose energy levels are comparable to those of the commercially available n-type semiconductors     

System for calculating the linear temperature-programmed retention indices of polycyclic aromatic compounds

Theoretical procedures have been used to predict linear temperature-programmed retention indices for polycyclic aromatic compounds. It is possible to calculate such indices for polycyclic aromatic compounds in some practical situations in which the compounds cannot be eluted during a simple linear temperature program. The theory has been tested for a number of polycyclic aromatic hydrocarbon (PAHs) in single- and multi-plateau temperature-programmed gas chromatography with SE-52 as the stationary phase. This method will extend the applicability of linear retention indices for the identification of the isomers of polycyclic aromatic compounds.     

Reactions of diazoalkanes with unsaturated compounds

A systematic study has been conducted of the catalytic reaction of diazomethane with cyclic and polycyclic unsaturated hydrocarbons, conjugated dienes, as well as with a series of functionalized unsaturated compounds. The feasibility of using transition metal, nontransition metal, and rare earth metal compounds of, for example, Co, Ni, Zr, Cr, Rh, and Dy, has been demonstrated for the first time. It has also been established that Pd(acac)₂ has very high activity as a catalyst for the cyclopropanation of terminal and endocyclic double bonds by diazomethane, and that its activity is reduced upon the introduction of n-donor ligands or in the presence of strong polar solvents.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1861–1869, August, 1989.     

Friedel-Crafts alkylation of a cage enone: synthesis of aralkyl substituted tetracyclo[5.3.1.0.0]undeca-9,11-diones and the formation of fascinating novel cage compounds with pyrrole and thiophene using Montmorillonite K-10

The intrinsic catalytic properties of Montmorillonite K-10 clay have been utilized for Friedel-Crafts alkylation of the polycyclic caged enone 1 using different carbo and heterocyclic aromatic systems leading to novel compounds. Carbon-carbon bond formation between the aromatic compounds and the cage system has led to three different types of products.     

Oxidative dearomatization and retro-Diels-Alder/Diels-Alder cascade: Synthesis and photoreactions of azepane annulated bicyclo[2.2.2]octenone

Synthesis of azepane annulated bicyclo[2.2.2]octenone via oxidative dearomatization and intramolecular π⁴s?+?π²s cycloaddition has been described. Manipulation of the adduct led to tricyclic compounds having a β,γ-enone chromophore whose photoreaction upon triplet and singlet excitation furnished polycyclic systems having azepane ring systems.     

Surfactant cloud point extraction and preconcentration of organic compounds prior to chromatography and capillary electrophoresis

The use of preconcentration steps based on phase separation by the cloud point technique offers a convenient alternative to more conventional extraction systems. It has been used successfully for the preconcentration of species of widely differing character and nature, such as metal ions, proteins and other biomaterials, or organic compounds of strongly differing polarity. Here we address the most recent analytical applications of this methodology when used as an isolation and trace enrichment step prior to the analysis of organic compounds (polycyclic aromatic hydrocarbons, polychlorinated compounds, pesticides, phenolic derivatives, aromatic amines, vitamins, etc.) via liquid and gas chromatography or capillary electrophoresis.     

Influence of silicon defects on the adsorption of thiophene-like compounds on polycyclic aromatic hydrocarbons: a theoretical study using thiophene + coronene as the simplest model

Physisorption and chemisorption processes of thiophene on coronene and 2Si-coronene have been studied using density functional theory and MP2 methods. These systems have been chosen as the simplest models to describe the adsorption of thiophene-like compounds on polycyclic aromatic hydrocarbons (PAHs). The calculated data suggest that the presence of silicon atoms in PAHs could favor their interaction with thiophene and similar compounds. Small stabilization energies have been found for several physisorbed complexes. The thiophene chemisorption on coronene seems very unlikely to occur, while that on 2Si-coronene leads to addition products which are very stable, with respect to the isolated reactants. These chemisorption processes were found to be exoergic (DeltaG < 0) in the gas phase and in the nonpolar liquid phase. The results reported in this work suggest that silicon defects on extended polycyclic aromatic hydrocarbons, such as graphite, soot, and large-diameter carbon nanotubes, could make them useful in the removal processes of aromatic sulfur compounds from oil hydrocarbons.     

Synthèse de dérivés de la benzo[c] quinolizine

The introduction of polar groups in planar polycyclic systems, for the purpose of studying their intercalating action, has been realized in the benzo[c]quinolizinium series. A functionalizing synthesis has been developed from 2-picolyl-and quinaldyllithium. Intermediate ketones or imines were cyclized by a quaternization reaction involving a concerted process. Structure and physico-chemical features of the compounds prepared were studied.     

Phosphaalkynes—Syntheses,Reactions, Coordination Behavior [New Synthetic Methods (73)]

Organophosphorus compounds have been applied in two ways in chemical synthesis. They can either be used as a reagent in a step of the synthesis (for example, in the Wittig reaction) or they can be incorporated directly into the target molecule. This second application, in particular, has expanded greatly in the last few years with the preparation of low-coordination phosphorus compounds. These include the phosphaalkynes, which are of great interest to organic and inorganic chemists. Phosphaalkynes have been employed in the synthesis of heterocyclic compounds, phosphaarenes and their valence isomers, and polycyclic compounds. Further applications have been the use of phosphaalkynes as new ligand systems in complex chemistry and their cyclooligomerization with organometallic reagents. While the chemical properties of phosphaalkynes have little in common with those of nitriles, they are in many ways very similar to those of the isoelectronic acetylenes.     

Critical point measurement of some polycyclic aromatic hydrocarbons

The critical temperatures and the critical pressures of five polycyclic aromatic compounds, namely, acenaphthene, fluorene, anthracene, phenanthrene, and pyrene have been measured. All the compounds studied decompose at near-critical temperatures. A pulse-heating technique applicable to measuring the critical properties of thermally unstable compounds has been used. The times from the beginning of a heating pulse to the moment of reaching the critical temperature were from (0.06 to 0.85) ms. The short residence times provide little degradation of the substances in the course of the experiments. The experimental critical parameters of the polycyclic aromatic compounds have been compared with those estimated by five predictive methods. The acentric factors of polycyclic aromatic compounds studied have been calculated.     

Cellulose bearing covalently linked copper phthalocyanine trisulphonate as an adsorbent selective for polycyclic compounds and its use in studies of environmental mutagens and carcinogens.

A method useful as a preconcentration technique for isolating mutagens and carcinogens is described. Cotton bearing covalently linked copper phthalocyanine trisulphonate as ligand (blue cotton) can adsorb selectively compounds having three or more fused rings. The adsorption takes place in aqueous media, involving 1:1 complex formation between the ligand and the polycyclic compound. The desorption can be done by elution with organic solvents, most effectively with methanol containing ammonia. As many important environmental mutagens and carcinogens are polycyclics, this adsorption is useful as a means of extracting this class of materials from crude samples such as food, urine and river waters. The use of copper phthalocyanine as a ligand for chromatographic supports has recently been initiated, yielding promising results for the effective separation of polycyclic aromatic compounds from each other.     

Algebraic characterization of bridged polycyclic compounds

An approach based on the topological distance matrix is used for algebraic characterization of bridged polycyclic compounds. The classical bridged structures which have external bridges between cycles were examined together with the more complicated three-dimensional polycyclic systems regarded as containing internal bridges. Thirteen rules are given for characterizing the main types of structural rearrangements in these compounds. The important topological characteristic of (poly)cyclic systems, the molecular cyclicity, is examined in the polycyclic condensed, spiro- and bridged structures, respectively.     

Carbon-carbon bond formation in regio- and stereoselective palladium-catalyzed cyclization of allene-substituted conjugated dienes.

Regio- and stereoselective palladium-catalyzed reactions of allene-substituted 1,3-dienes 1 in acetic acid at room temperature lead to cyclization with formation of a carbon-carbon bond between the middle carbon of the allene and the terminal carbon of the 1,3-diene. Two different types of reactions, both that constitute 1,4-carboacetoxylations of the 1,3-diene, have been developed. In one of the reactions, Pd(II) catalyzes the oxidation of 1 to bicyclic compounds 2, and in the other, Pd(0) catalyzes the transformation of 1 to bicyclic compounds 3. The products 2 are useful for further synthetic transformations and undergo Diels-Alder reactions with dienophiles to give polycyclic ring systems.     

Review of Sublimation Thermodynamics of Polycyclic Aromatic Compounds and Heterocycles

This review details sublimation vapor pressure and thermodynamic data on 85 polycyclic aromatic compounds and heterocycles from the early 1900s through 2012. These data were collected using a variety of vapor pressure measurement techniques, from effusion to gas saturation to inclined‐piston manometry. A brief overview of each measurement technique is given; these methods yield reproducible sublimation vapor pressure data for low volatility organic compounds such as polycyclic aromatic compounds and heterocycles. Several conclusions can be drawn from this literature survey, specifically that there remains a dearth of data on the sublimation thermodynamics (and fusion thermodynamics) of heteroatomic high molecular weight aromatic compounds, inhibiting a holistic understanding of the effect of specific heteroatoms and substituent position on the thermodynamics of these compounds. However, we can clearly see from the data that there are a variety of potential intermolecular interactions at work that generally tend to increase the enthalpy of sublimation and decrease the vapor pressure of a substituted polycyclic aromatic compound/polycyclic heterocycles versus its parent compound.     

The aza-Wittig reaction: an efficient tool for the construction of carbon-nitrogen double bonds

Recent advances in the aza-Wittig reaction of phosphazene derivatives with several carbonyl compounds are reviewed. Phosphazenes afford inter- and intramolecular aza-Wittig reactions with different compounds such as aldehydes, ketones, esters, thioesters, amides, anhydrides and sulfimides. One of the most important applications of this reaction is the synthesis of a wide range of acyclic and heterocyclic compounds, ranging from simple monocyclic compounds to complex polycyclic and macrocyclic systems.     

Progress on PPAPs cyclization: Guttiferone A as a case study

Guttiferone A and cyclized analogs are naturally occurring polycyclic polyprenylated acyl phloroglucinols possessing antiparasitic activities. Naturally occurring xanthones possess increased activity, but are either rare or difficult to synthesize. In this paper, three optimized methodologies to access natural, hydroxylated and non-natural xanthonic skeletons from guttiferone A are described. These compounds will serve as starting materials for further SAR studies.