Synthesis of symmetrical trisubstituted olefins by cross metathesis

[reaction: see text] Trisubstituted alkenes have been prepared via intermolecular olefin cross-metathesis (CM) between alpha-olefins and symmetrically 1,1-disubstituted olefins using an imidazolylidene ruthenium benzylidene complex. Of particular interest is the synthesis of isoprenoid/prenyl groups by a simple solvent-free CM reaction with isobutylene. In addition, prenyl groups can also be installed by a cross-metathesis of 2-methyl-2-butene with a variety of alpha-olefins at room temperature with low catalyst loadings.     

A highly selective method for the synthesis of symmetrical trisubstituted pyridines using transition and non-transition metal salts

Conclusions New highly selective catalysts derived from non-transition metal salts (ZnCl₂ and InCl₃) and bimetallic systems (AlCl₃-NiCl₂ or AlCl₃-PdCl₂) were developed which permit the preparation of symmetrical trialkylpyridines in high yield from carboxylic acid chlorides, isobutylene and ammonia.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 688–690, March, 1986.     

Derivatives of carbamide, symmetrical triazines, and heptazines: Ecologically clean fire retardants for different thermostable compositions

The problems of replacing conventional halogen-containing fire retardants with alternative products, such as carbamide and symmetrical triazines and heptazines obtained on its basis, as well as different phosphates and ammonium polyphosphates, are considered. The main properties of the suggested compounds are described. It is shown that the range of compounds can be used, not only as fire retardants, but also as curing or modifying agents for polymer compositions, thermostabilizers of resins (based on ethylene-propylene rubbers) and sealants, and components of thermostable organosilicon compositions.     

The markovnikoff hydroboration of a trisubstituted olefin

Hydroboration-oxidation of akuammicine $\text{1}$ mainly gave the tertiary alcohol $\text{2}$ Hydroboration-oxidation of double bonds is a well known anti-Markovnikoff process^1,2. In the course of applications of this method to the indole alkaloid field, the following Markovnikoff hydration of a trisubstituted olefin was surprisingly observed :

     

One‐step synthesis of 2,4,5‐trisubstituted pyrimidines

A simple and straightforward methodology towards the synthesis of 2,4,5‐trisubstituted pyrimidines has been developed by one‐step reaction of isoflavones with thiourea or guanidine. Ten 2‐mercapto‐4,5‐diphenylpyrimidines and eight 2‐amino‐4,5‐diphenylpyrimidines were reported. All of them were characterized by FT‐IR, NMR, and elemental analysis. A variety of substrates can participate in the process with good yields and high purities, making this methodology suitable for library synthesis in drug discovery. J. Heterocyclic Chem., (2011).     

On the stereospecific conversion of proximally-oxygenated trisubstituted vinyltriphenylstannanes into stereodefined trisubstituted alkenes

[reaction: see text] Allylically oxygenated vinyl alpha-triphenylstannanes such as 22 can be readily converted into vinyl iodides and thereafter stereodefined trisubstituted alkenes with retention of configuration.     

Dendrimers based on [1,3,5]‐triazines

A comprehensive and chronological account of dendrimers based on [1,3,5]‐triazines is provided. Synthetic strategies to install the triazine through cycloaddition, cyclotrimerization, and nucleophilic aromatic substitution of cyanuric chloride are discussed. Motivations and applications of these architectures are surveyed, including the preparation of supramolecular assemblies in the solution and solid states and their use in medicines, advanced materials, and separations when anchored to solid supports. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3411–3433, 2006     

The reaction of diazomethane with double bonds—I Direct methylation of trisubstituted ethylenes

The reaction of -carbomethoxy-γ-benzylidenebutenolide with diazomethane has been studied, and the β-methylbutenolide structure of the resulting product established through degradative and synthetic work. Extension of this direct C-methylation to other related butenolides is presented. Hydrogenation of enol lactones is discussed in some detail.     

Transformations of phenylhydrazones of 5‐acyl‐1,2,4‐triazines to pyrazolo[4,3‐e][1,2,4]triazines or 4‐cyanopyrazole

A simple and high yielding preparation of pyrazolo[4,3‐e][1,2,4]triazines and 4‐cyano‐3‐methyl‐1‐phenylpyrazole derivatives from corresponding phenylhydrazones of 5‐acyl‐1,2,4‐triazines by melt under acidic medium and by thermal heating, respectively.     

Synthesis and crystallographic studies of two new 1,3,5‐triazines

The synthesis and characterization of two new 1,3,5‐triazines containing 2‐(aminomethyl)‐1H‐benzimidazole hydrochloride as a substituent are reported, namely, 2‐{[(4,6‐dichloro‐1,3,5‐triazin‐2‐yl)amino]methyl}‐1H‐benzimidazol‐3‐ium chloride, C₁₁H₉Cl₂N₆⁺·Cl^? ( 1 ), and bis(2,2′‐{[(6‐chloro‐1,3,5‐triazine‐2,4‐diyl)bis(azanediyl)]bis(methylene)}bis(1H‐benzimidazol‐3‐ium)) tetrachloride heptahydrate, 2C₁₉H₁₈ClN₉²⁺·4Cl^?·7H₂O ( 2 ). Both salts were characterized using single‐crystal X‐ray diffraction analysis and IR spectroscopy. Moreover, the NMR (¹H and ¹³C) spectra of 1 were obtained. Salts 1 and 2 have triclinic symmetry (space group P) and their supramolecular structures are stabilized by hydrogen bonding and offset π–π interactions. In hydrated salt 2 , the noncovalent interactions yield pseudo‐nanotubes filled with chloride anions and water molecules, which were modelled in the refinement with substitutional and positional disorder.     

Catalytic asymmetric synthesis of trisubstituted aziridines

A method is described which provides for the direct asymmetric catalytic synthesis of trisubstituted aziridines from imines and diazo compounds. While unactivated imines were not reactive to α-diazo carbonyl compounds in which the diazo carbon was disubstituted, N-Boc imines react with both α-diazo esters and α-diazo-N-acyloxazolidinones to give trisubstituted aziridines with excellent diastereo- and enantioselectivities.     

Highly enantioselective cyclopropanation of trisubstituted olefins

A highly efficient asymmetric cyclopropanation of trisubstituted olefins with methyl diazoacetate has been developed in terms of an elaborate modified chiral bisoxazoline/copper complex as a catalyst. A broad scope of substrates is compatible with this catalyst system, including various trisubstituted olefins bearing different aryl-, fused aryl- and alkyl-substituents, providing an easy access to optically active 1,1-dimethyl cyclopropanes in good yields with excellent diastereo- and enantio-selectivity.     

Conversion of Stilbene to trisubstituted Olefins

Determination of the stereochemistry of bromination-dehydrobromination of both cis and trans-stilbene has been achived. Coupling of the resulting vinyl bromides with alkyl or aryl groups have been done. The coupling products could serve as intermediates for the synthesis of biologically active tetrasubstituted olefins.     

Organocatalytic stereoselective epoxidation of trisubstituted acrylonitriles

The first diastereospecific and enantioselective epoxidation of trans-2-aroyl-3-arylacrylonitriles by means of the commercially available diaryl L-prolinol/tert-butyl hydroperoxide system has been developed. These diversely functionalized epoxides were obtained in excellent yield (up to 99%), complete diastereoselectivity for the trans-isomer, and good enantioselectivity (up to 84% ee). Highly enantioenriched epoxides can be easily obtained after a single crystallization (ee > 90%).     

The phase behavior of two-dimensional symmetrical mixtures

Using Monte Carlo simulation methods in the grand canonical and semigrand canonical ensembles, we study the phase behavior of two-dimensional symmetrical binary mixtures of Lennard-Jones particles. We discuss the interplay between the demixing transition in a liquid and the freezing in detail. Phase diagrams for several systems characterized by different parameters describing interactions in the system are presented. It is explicitly demonstrated that different scenarios involving demixing and freezing transitions, described in our earlier paper [A. Patrykiejew and S. Soko?owski, Phys. Rev. E, 81, 012501 (2010)], are possible. In one class of systems, the λ-line representing a continuous demixing transition in a liquid phase starts at the liquid side of either the vapor-liquid or liquid-solid coexistence. The second class involves the systems in which the λ-line begins at the liquid side of the vapor-liquid coexistence, in the lower critical end point, and then terminates at the liquid side of the liquid-solid coexistence, in the upper critical end point. It is also shown that in such systems the solid phase may undergo a demixing transition at the temperature above the upper critical end point.     

Synthesis of some polycyclic 1,2,4‐triazines disposing of acidic N‐H group

7‐(6‐Azauracil‐5‐yl)‐isatin 1 was converted through its thiosemicarbazone 2 to 6‐(6‐azauracil‐5‐yl)‐2,3‐dihydro‐5H‐1,2,4‐triazino[5,6‐b]indol‐3‐thione 3 and through the thiosemicarbazone of appropriate isatinic acid to 2‐(2‐thio‐6‐azauracil‐5‐yl)‐6‐(6‐azauracil‐5‐yl)‐aniline 4. The course of the cyclocondensation of this compound was studied and the reaction was found to proceed in both possible ways, resulting in a mixture of compound 3 and regioisomer 6‐(2‐thio‐6‐azauracil‐5‐yl)‐2,3‐dihydro‐5H‐1,2,4‐triazino[5,6‐b]‐indol‐3‐one 5. Substituted aniline 4 was oxidized to 2,6‐bis‐(6‐azauracil‐5‐yl)‐aniline 7 , which served for the preparation of hydrazone 8 , cyclization of which led to 1‐[2,6‐bis‐(6‐azauracil‐5‐yl)‐phenyl]‐6‐azauracil‐5‐carbonitrile 9. This is the first tricyclic 6‐azauracil with vicinal arrangement of 6‐azauracil rings.