Mesogenic properties of cycloalkylmethyl 4-(4'-octoxybiphenyl-4-carbonyloxy)benzoate

Four analogous compounds, cyclohexylmethyl 4-(4'-octoxybiphenyl-4-carbonyloxy)benzoate (2), cyclopentylmethyl 4-(4'-octoxybiphenyl-4-carbonyloxy)benzoate (3), cyclobutylmethyl 4-(4'-octoxylbiphenyl-4-carbonyloxy)benzoate (4) and cyclopropylmethyl 4-(4'-octoxylbiphenyl-4-carbonyloxy)benzoate (5) were prepared. They all exhibit SmA, SmC and SmX phases.     

The synthesis and liquid crystal properties of some 4-n-nonylphenyl esters of 3-(4'-n-alkoxybiphenylyl)- and 3-(4'-n-alkoxybiphenylyl)-3-methyl-propanoic acids and their laterally fluorinated analogues

A number of 4-n-nonylphenyl esters and mono- and di-fluorinated 4-n-nonylphenyl esters derived from 3-(4'-n-alkoxybiphenylyl)propanoic acids (II) have been synthesized and their thermotropic liquid crystal properties assessed with a view to obtaining tilted smectic phases for possible use in ferroelectric display devices. Many of these compounds exhibit wide temperature range S_C and S_I/F phases, but none gave the ideal phase sequence S_C-S_A-N-I mainly because the structure of these compounds was not conducive to the formation of the nematic phase. To try to alleviate this problem a series of 4-n-nonylphenyl esters based on 3-(4'-n-alkoxybiphenylyl)-3-methylpropanoic acid was prepared, where a lateral methyl group was incorporated in the β-position of the -CH₂CH₂CO₂- linkage. Incorporation of the lateral methyl group encouraged the formation of a nematic phase at the expense of both the smectic A phase and tilted smectic phases.     

3-Aryl- or 3-(trans-4-alkylcyclohexyl)- 6-arylcyclohex-2-enones: synthesis,transformations and mesomorphic properties

The synthesis and chemical transformations of 3-aryl- or 3-(trans-4-alkylcyclohexyl)- 6-arylcyclohex-2-enones into liquid crystalline compounds are discussed. These 3,6-disubstituted cyclohex-2-enones were prepared by the condensation of appropriate Mannich salts or trans-4-alkylcyclohexyl 2-bromoethyl ketones with 4-substituted benzyl methyl ketones.     

3-Aryl- or 3-(trans-4-alkylcyclohexyl)- 6-arylcyclohex-2-enones: synthesis, transformations and mesomorphic properties

The synthesis and chemical transformations of 3-aryl- or 3-(trans-4-alkylcyclohexyl)- 6-arylcyclohex-2-enones into liquid crystalline compounds are discussed. These 3,6-disubstituted cyclohex-2-enones were prepared by the condensation of appropriate Mannich salts or trans-4-alkylcyclohexyl 2-bromoethyl ketones with 4-substituted benzyl methyl ketones.     

Reactions of 2-, 3-, and 4-(N-nitroso)methylaminopyridine with esters containing active methylene groups

2-N-Nitrosomethylaminopyridine but not 2-methylaminopyridine, 3-N-nitrosomethylamino- or 3-methyl-aminopyridine and 4-N-nitrosomethylamino- or 4-methylaminopyridine react with malonate esters to form the corresponding derivatives of carbamates, amides and dihydropyridines respectively. In the reaction of the 4-isomers with diisopropyl malonate small amounts of the corresponding carbamates was also formed.     

A novel method for preparation of 2-(methyl- or phehnylthio)alkanoic esters

Ethyl 2-acetylalkanoate gave ethyl 2-(methyl- or phenylthio)alkanoate in high yield on treatment wiht CH₃SSO₂CH₃, PhSSO₂Ph, or PhSSPh in the presence of small excess of EtONa in EtOH. Application of the present method to synthesis of pellitorine and the queen substance is also described.     

3-(2-Cyanoethyl)-6-aryl- or 6-(trans-4-alkylcyclohexyl)cyclohex-2-enones: synthesis,transformations and mesomorphic properties

The synthesis and chemical transformations of 3-(2-cyanoethyl)-6-aryl- or 6-(trans-4-alkylcyclohexyl)cyclohex-2-enones into nematic and smectic liquid crystalline compounds are discussed. These 3,6-disubstituted cyclohex-2-enones were prepared by the condensation of appropriate Mannich salts or trans-4-alkylcyclohexyl 2-bromoethyl ketones with ethyl 2-(2-cyanoethyl)acetoacetate.     

3-(2-Cyanoethyl )-6-aryl- or 6-(trans-4-alkylcyclohexyl)cyclohex-2-enones: synthesis, transformations and mesomorphic properties

The synthesis and chemical transformations of 3-(2-cyanoethyl)-6-aryl- or 6-(trans-4-alkylcyclohexyl)cyclohex-2-enones into nematic and smectic liquid crystalline compounds are discussed. These 3,6-disubstituted cyclohex-2-enones were prepared by the condensation of appropriate Mannich salts or trans-4-alkylcyclohexyl 2-bromoethyl ketones with ethyl 2-(2-cyanoethyl)acetoacetate.     

3-(2-methylthiopyridin-3-yl)-3-oxopropionic esters

A reaction of alkyl bromoacetates with substituted 3-cyano-2-methylthiopyridines in the presence of zinc dust furnishes 3-amino-3-(2-methylthiopyridin-3-yl)propenoic esters. Their hydrolysis under mild conditions leads to 3-(2-methylthiopyridin-3-yl)-3-oxopropionic esters. The latter were used in the synthesis of pyridine-substituted pyrazolones.     

Molecular docking,synthesis and anticonvulsant activity of some novel 3-(2-substituted)-4-oxothiazolidine-3-yl)-2-phenylquinazoline-4(3H)-ones

Research on Chemical Intermediates - As the therapeutic potential of quinazolinone and thiazolidinone is well mentioned in literature for their versatile biological activities, their related...     

Structure,tautomerism, and transformations of β-(3-nitro-2-pyridyl)- and β-(3-nitro-4-pyridyl)pyruvic acid esters

It was shown by means of IR, UV, and PMR spectra that -(3-nitro-2-pyridyl)pyruvic acid esters are practically completely enolized in the crystal state and in solution; ethyl -(3-nitro-4-pyridyl)pyruvate has an enol structure in the crystalline state and in pyridine solution but exists as a mixture of keto and enol forms in low-polarity solvents.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 389–393, March, 1974.     

Synthesis of lithium,sodium, cesium,and calcium salts of (E)-4- or (E,S)-3-methyl-2-(5-arylisoxazol-3-yl)-methyleneaminobutanoic, (E,S)-4-methyl-2- or (E,2S,3S)-3-methyl-2-(5-arylisoxazol-3-yl)methyleneaminopentanoic,and (E)-6-(5-arylisoxazol-3-yl)methyleneaminohexanoic acids

Preparative method for the synthesis of lithium, sodium, cesium, and calcium salts of (E)-4-(5-arylisoxazol-3-yl)methyleneaminobutanoic, (E)-6-(5-arylisoxazol-3-yl)methyleneaminohexanoic, (E,S)-3-methyl-2-(5-arylisoxazol-3-yl)methyleneaminobutanoic, (E,S)-4-methyl-2-(5-arylisoxazol-3-yl)methyleneaminopentanoic and (E,2S,3S)-3-methyl-2-(5-arylisoxazol-3-yl)methyleneaminopentanoic acids was developed by reacting 5-phenyl(4-tolyl)isoxazole-3-carbaldehydes with amino acids like 4-aminobutyric and 6-aminocaproic acids, L-valine, L-leucine or L-isoleucine in the presence of lithium hydride, sodium methoxide, cesium carbonate or calcium hydride in boiling methanol.     

Synthesis and properties of 3-cyano-4-(4-cyanophenyl)-1,4-dihydropyridine-2(3H)-thiones

Piperidinium 3-cyano-4-(4-cyanophenyl)-1,4-dihydropyridine-2(3H)-thiolates were obtained by the condensation of 1,3-dicarbonyl compounds, 4-cyanobenzaldehyde, and cyanothioacetamide in the presence of an equimolar amount of piperidine. The acidification of these thiolates gave the corresponding 1,4-dihydropyridine-2(3H)-thiones and pyridine-2(1H)-thione. Alkylation of 1,4-dihydropyridine-2-thiolates or the reaction mixture of the three-carbon condensation using iodacetamide gave 2-carbamoylmethylthio-1,4,5,6-tetrahydro- or 1,4-dihydropyridines, which were characterized by their conversion to 4,7-dihydrothieno[2,3-b]pyridines.Latvian Institute of Organic Synthesis, LV-1006, Riga, LatviaTranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 794–798, June, 2000.     

Cosorption of Zn(II) and 2-, 3-, or 4-aminopyridine by montmorillonite

Data from acid-base titrations at 25 degrees C of Zn(NO(3))(2) and 2-, 3-, or 4-aminopyridine in 10 mM KNO(3) as background electrolyte suggested that soluble complexes ZnL(2+) and Zn(OH)L(+) form, where L represents aminopyridine. Zinc-hydroxyaminopyridine complexes have not been reported previously. The cosorption of Zn(II) with each of the aminopyridines to K-saturated Wyoming (SWy-K) and Texas (STx-K), and Ca-enriched Texas (STx-Ca) montmorillonites was measured at 25 degrees C, with 10 mM KNO(3) or 3.3 mM Ca(NO(3))(2) as background electrolyte. Comparison with previous data for sorption of Zn(II) and the aminopyridines separately and surface complexation modeling of the cosorption data showed that under acid conditions competition between Zn(2+) and aminopyridinium ions for the permanent negatively charged sites of montmorillonite results in suppression of the uptake of each sorbate by the other, but only when a large excess of the competing sorbate is present. Under alkaline conditions the sorption of Zn(II) was not affected by the presence of even a large excess of aminopyridine, but the sorption of 4-aminopyridine in particular was slightly enhanced when a large excess of Zn(II) was present. The enhancement was attributed to the formation of metal-bridged ternary surface complexes at the variable-charge sites on the edges of the montmorillonite crystals.     

The novel azomethine ligands for binuclear copper(II) complexes with ferro- and antiferromagnetic properties

A series of novel binuclear ferro- and antiferromagnetic Cu(2+) chelates of structurally broadly varied Schiff bases (derived from o-tosylamino(hydroxyl)benzaldehydes and monoalkylated o-phenylenediamine, o-aminophenol, o-aminothiophenol, 1,2-diaminobenzimidazole, 1-aminobenzimidazoline-2-thione) and β-diketimines (derived from 2,6-di-i-Pr-aniline) has been prepared. The tautomerism of the ligands and structureof their copper complexes have been studied with the use of IR, ¹H NMR EPR and EXAFS spectroscopy. Molecular and crystal structure of a β-diketimine copper dimer has been determined by X-ray crystallography. The magnetic measurements (2–300?K) performed for all the complexes showed that the ferro- and antiferromagnetic character of the exchange interaction depends both on the structure of the coordination site (origin of the ligating centers) and the structure of the ligands (in particular, on the type of the cycle annelated to the bridging fragment). Whereas S-binding metal chelates 13 (X?=?NTs, Y?=?S, R?=?H) are diamagnetic, the complexes 15 with annelated azole moieties are ferromagnetic.     

Polymesomorphism in a homologous series of 2-(4-alkoxyphenyl)-5-(4-methylphenyl)pyridines

A new series of 2-(4- n -alkoxyphenyl)-5-(4-methylphenyl)pyridines (CH C H C H NC HOC H , n 1-10) (APMPP), which are teraryl compounds containing a pyridine ring in n 2 m 1 the centre position of the rigid core, was synthesized and the phase transitions of the homologues were studied using DSC measurements, polarizing optical microscopy and miscibility tests with terephthalylidene-bis-4- n -pentylaniline (TBPA). Only a nematic phase was found for the shorter alkoxy homologues with n 4. The longer alkoxy homologues with n 4 showed the sequence of enantiotropic phase transitions CrG-SmF-SmC-SmA-N-I, while a monotropic CrH phase was observed for the n 5-10 homologues. Interestingly, the polymesomorphisms appear when n is larger than 4. 3 6 4 5 3 6 4     

Synthesis and E/Z configuration determination of novel derivatives of 3-aryl-2-(benzothiazol-2'-ylthio) acrylonitrile, 3-(benzothiazol-2'-ylthio)-4-(furan-2'-yl)-3-buten-2-one and 2-(1-(furan-2'-yl)-3'-oxobut-1'-en-2-ylthio)-3-phenylquinazolin-4(3H)-one

Knoevenagel condensation of 2-(benzothiazol-2-ylthio) acetonitrile (2) with either furan-2-carbaldehyde or thiophene-2-carbaldehydes leads to E-isomers 4a-b exclusively, while the condensation of the compound 2 with benzaldehyde or para-substituted benzaldehydes with an electron-donating group afforded E/Z mixtures 4c-e with preferentially formation of the E-isomer. Condensation of furan-2-carbaldehyde (3a) with either 1-(benzothiazol-2'-ylthio) propan-2-one (5) or 2-(2'-oxo propylthio)-3-phenyl-quinazolin-4(3H)-one (9) leads exclusively to the Z-isomers of 6 and 10, respectively. The structures of the newly synthesized compounds were elucidated by elemental analyses, 1H-NMR and 13C-NMR spectra, COSY, HSQC, HMBC, NOE, MS and X-ray crystallographic investigations.     

Synthesis and biological activities of novel dialkyl (4-trifluoromethylphenylamino)-(4-trifluoromethyl or 3-fluorophenyl) methylphosphonates

A series of novel dialkyl (4-trifluoromethylphenylamino)-(4-trifluoromethyl or 3-fluorophenyl) methylphosphonates 3 were synthesized through the reaction of 3-fluorobenzaldehyde or 4-trifluoromethylbenzaldehyde and 4-trifluoromethylaniline with dialkyl phosphite by microwave irradiation using boron trifluoride-ether catalyst and their structures were clearly verified by spectroscopic data (IR, ¹H NMR and elemental analysis). The results of bioassay showed that these title compounds possess potential anticancer activities in vitro by MTT method. At the same time, we found these title compounds exhibit moderate antiviral activity against tobacco mosaic virus.     

Synthesis, thermal stabilities, and anisotropic properties of some new isoflavone-based esters 7-decanoyloxy-3-(4'-substitutedphenyl)-4H-1-benzopyran-4-ones

A series of new isoflavonic esters 7-decanoyloxy-3-(4'-substitutedphenyl)-4H-1-benzopyran-4-ones containing a heterocycle in their central core with one flexible alkyl chain and various substituents, R (where R = F, Cl, Br, CH₃, OCH₃, or H) at 4'-position at one end, have successfully been synthesised, isolated, and characterised. The physical properties of title compounds were studied using spectroscopic techniques (Fourier transform infrared, ¹H and ¹³C nuclear magnetic resonance). The liquid crystalline properties and the textures of these compounds along with their thermal stabilities were investigated via polarising optical microscopy and differential scanning calorimetry. All the compounds except the member without the substituent were enantiotropic mesogens exhibiting smectic A and/or nematic phases. The layer periodicities in relation to different phases were substantiated by X-ray diffraction wherein the molecules within the SmA phase were found to be intercalated. The structural changes that resulted in a variation of transition temperature as well as the electronic polarisability of the respective compounds are also discussed.     

Synthesis and reactions of methyl esters of 4-(3-r-sydnonyl)-2, 4-dioxobutanoic acid with bromine and p-tolyl azide

Chemistry of Heterocyclic Compounds -