Stereochemistry of the asymmetric reduction of (1′s)-1,3-dimethyl-4(1′-phenylethylimino)piperidine

The stereochemistry of the asymmetric reduction of the imine obtained from 1,3-dimethylpiperidin-4-one and (S)--phenylethylamine has been studied. It is shown that hydride reduction of imine 1 by sodium borohydride in methanol is asymmetric and gives the cis and trans diastereomeric pair 1,3-dimethyl-4-(-phenyl-ethylamino) piperidine in the ratio 3:1. Using sodium in isopropanol gives only one trans diastereomeric pair.¹H NMR has been used to identify the stereochemical structure and diastereomer excess of the cis and trans isomers of 1,3-dimethyl-4-(-phenylethylamino)piperidine which had been separated by column chromatography.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 219–221, February, 1996.     

Effect of solvent on the crystal structures of copper(II) complexes based on 4′-(4-methoxyphenyl)-2,2′:6′,2″-terpyridine and 4′-(3-chlorophenyl)-2,2′:6′,2″-terpyridine

Four homoleptic copper(II) complexes, [Cu(Meophtpy)₂](ClO₄)₂ (Meophtpy = 4′-(4-methoxylphenyl)- 2,2′:6′,2″-terpyridine) (I), [Cu(Meophtpy)₂](ClO₄)₂ · 2H₂O (II), [Cu₂(m-Clphtpy)₄](ClO₄)₄ (m-ClPhtpy = 4′-(3-chlorophenyl)-2,2′:6′,2″-terpyridine) (III), and [Cu₂(m-ClPhtpy)₄](ClO₄)₄ (IV) have been synthesized by hydrothermal methods and characterized by IR, elemental analysis and single crystal X-ray diffraction (CIF files CCDC nos. 963375 (I), 885457 (II), 963377 (III), and 963376 (IV)). Complex II is a polymorph of I and complex IV is a polymorph of III. All these complexes are obtained with 95% ethanol solution or 50% ethanol solution and the solvent control on the crystallization are obviously found. In all complexes, the face-to-face interactions between pyridyl rings or phenyl rings facilitate the construction of 3D network in the crystal in addition to hydrogen bonds. The fluorescence properties of these complexes have been investigated.     

Influence of 4-[(E)-(4′-Heptyloxyphenyl)diazenyl]phthalonitrile on the Properties of a Cyanobiphenyl Liquid Crystal Mixture

Russian Journal of General Chemistry - The mesomorphic properties of 4-[(E)-(4′-heptyloxyphenyl)diazenyl]phthalonitrile (7O-AB-CN2) were studied by polarization microscopy and DSC method....     

Study of the inhibiting activity of 4-(4′-hydroxyphenyl)-and 4-(2′-hydroxy-5′-methylphenyl)methyl cyclohexane carboxylic acid ethyl esters in photooxidation of petroleum phosphors

4-(4′-hydroxyphenyl)-and 4-(2′-Hydroxy-5′-methylphenyl)methyl cyclohexane carboxylic acid ethyl esters were synthesized from phenol and para-cresol. The structure of the esters synthesized was studied, and their inhibiting activity in photooxidation of a petroleum phosphor produced from the heavy pyrolysis tar fraction was examined.     

Photophysical Properties of 4′-(p-aminophenyl)-2,2′:6′,2′′-terpyridine

Spectral and photophysical investigations of 4′-(p-aminophenyl)-2,2′:6′,2′′-terpyridine (APT) have been performed in various solvents with different polarity and hydrogen-bonding ability.The emission spectra of APT are found to exhibit dual fluorescence in polar solvents, which attributes to the local excited and intramolecular charge transfer states, respectively. The two-state model is proven out for APT in polar solvent by the time-correlated single photon counting emission decay measurement. Interestingly, the linear relationships of different emission maxima and solvent polarity parameter are found for APT in protic and aprotic solvents, because of the hydrogen bond formation between APT and alcohols at the amino nitrogen N25. Furthermore, the effects of the complexation of the metal ion with tpy group of APT and the hydrogen bond formation between APT with methanol at the terpyridinenitrogen N4—N8—N14 are also presented. The appearance of new long-wave absorption and fluorescence bands indicates that a new ground state of the complexes is formed.     

Photoinduced isomerization of 4-(4′-dimethylaminostyryl) pyridine N-oxide

The effects of photoirradiation on the conformation state of 4-(4′-dimethylaminostyryl)pyridine N-oxide was studied by spectral (EAS, ¹H NMR, IR) and thermochemical methods. Trans→cis isomerization was found to proceed in 4-(4′-dimethylaminostyryl)pyridine N-oxide irradiated with light (λ ≤ 400 nm) in chloroform. The conversion of the trans form of 4-(4′-dimethylaminostyryl)pyridine N-oxide to the cis form depends on the time and intensity of irradiation. Maximum conversion was achieved when a photostationary mixture formed with a ratio of components trans:cis = 40:60. Further irradiation of the solutions of 4-(4′-dimethylaminostyryl)pyridine N-oxide in chloroform led to salification with HCl formed during the decomposition of CHCl₃.     

Molecular structure of 2,3-(4′-phenylacetyl)- and 2,3-(4′-diphenylacetyl)-benzo-15-crown-5

The conformational state of two benzo-crown ethers with substantially different physiological activity, 2,3-(4-phenylacetyl)- and 2,3-(4-diphenylacetyl)benzo-15-crown-5, was studied in crystals and solutions in CH₃CN and CCl₄ by x-ray crystallographic analysis, IR spectroscopy, and conformational calculations by the method of molecular mechanics. Transition from the crystalline state to solutions was found to be accompanied by a substantial change in the conformation of the macrocyclic ring of all the compounds studied. The nature of the substituent in the benzene ring and the polarity of the solvent have an influence on the conformational state of the macrocyclic ring of the free ligand, which, however, is not the determining factor in the change in the activity of the compounds. The COCCOC fragments of the macrocyclic framework are conformationally labile, readily passing from gauche to trans conformations and the reverse, which is promoted by the negligible energy barriers between the different conformations, determined in the work by a molecular mechanics method.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1819–1825, August, 1991.     

1,1-Bis-(4-methoxyphenyl)-1′-pyrenyl methyl (bmpm): a new fluorescent 5′ protecting group for the purification of unmodified and modified oligonucleotides

By replacing the phenyl by a pyrenyl in the dimethoxytrityl (DMTr) group commonly used for 5′-protection in oligonucleotide synthesis, we have obtained a fluorescent acid-labile protecting group which exhibits similar chemical properties to those of DMTr. Here we demonstrate the usefulness of the new protecting group in the purification of both charged and neutral DNA fragments.     

Preparation of (4′S) and (4′R)-Spiro(oxirane-2-4′-5α-cholestan-3′β-ol), Potent Inhibitors of 4-Methyl Sterol Oxidase

(4′R)- and (4′S)-Spiro(oxirane-2,4′-5α-cholestan-3′β-ol) (1) and (2) were made from (4′R)- and (4′S)-spiro(oxirane-2,4′-5α-cholestan-3-one) (8) and (9). Alkaline hydrogen peroxide oxidation of 4-methylene-5α-cholestan-3-one (7) gave compounds (8) and (9) as a readily separable (1:1) mixture. Reduction of (9) to (2) provided access to a compound which could not be made by other methods.     

Antimicrobial Activities of a Series of Diphenyl (4′-(Aryldiazenyl)Biphenyl-4-Ylamino)(Pyridin-3-YL)Methylphosphonates

Abstract

A series of diphenyl (4′-(aryldiazenyl)biphenyl-4-ylamino)(pyridin-3-yl)methyl- phosphonates 2–7 was synthesized in high yields and their antimicrobial activities were investigated. Some compounds showed high antimicrobial activities against Escherichia coli as a gram-negative bacterium, Bacillus subtilis and Staphylococcus aureus as gram-positive bacteria, and Candida albicans and Schccaromycies cerevisiae as fungi and at low concentrations (10–1000 μg/mL). Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Cobalt(II) complexes of 1,2-(diimino-4′-antipyrinyl)ethane and 4-N-(4′-antipyrylmethylidene)aminoantipyrine

Cobalt(II) complexes of the Schiff bases 1,2-(diimino-4-antipyrinyl)ethane (GA) and 4-N-(4-antipyrylmethylidene)aminoantipyrine (AA) have been prepared and characterised by elemental analysis, electrical conductance in non-aqueous solvents, i.r. and electronic spectra, as well as by magnetic susceptibility measurements. The complexes have the general formulae [Co(GA)X]X (X = ClO^– ₄ or NO₃ ^–), [Co(GA)X₂] (X = Cl^–, Br^– or I^–), [Co(AA)₂]X₂ (X = ClO₄ ^–, NO₃ ^–, Br^– or I^–) and [Co(AA)Cl₂]. GA acts as a neutral tetradentate ligand, coordinating through both carbonyl oxygens and both azomethine nitrogens. In the perchlorate and nitrate complexes of GA one anion is coordinated in a bidentate fashion, whereas in the halide complexes both anions are coordinated to the metal, generating an octahedral geometry around the Co ion. AA acts as a neutral bidentate ligand, coordinating through the carbonyl oxygen derived from the aldehydic moiety and the azomethine nitrogen. Both anions remain ionic in the perchlorate, nitrate, bromide and iodide complexes of AA, whereas both anions are coordinated to the metal ion in the chloride complex, resulting tetrahedral geometry around the Co ion.     

Why do non-symmetric dimers intercalate? The synthesis and characterisation of the α-(4-benzylidene-substituted-aniline-4′-oxy)-ω-(2-methylbutyl-4′-(4″-phenyl)benzoateoxy)alkanes

Ten new non-symmetric liquid crystal dimers belonging to the family of compounds α-(4-benzylidene-substituted-aniline-4′-oxy)-ω-(2-methylbutyl-4′-(4″-phenyl)benzoateoxy)-alkanes have been synthesised and their transitional properties characterised. The dimers contain either a hexamethylene or octamethylene spacer, while the terminal substituents on the 4-benzylideneaniline fragment are H, CH₃, F, Cl and Br. The unsubstituted dimers are not liquid crystalline, while the remaining compounds exhibit enantiotropic nematic behaviour. The trends in the clearing temperatures, according to the chemical nature of the terminal substituent, are largely consistent with those established for conventional low molar mass liquid crystals. Three of the dimers also exhibit an intercalated smectic A phase, specifically the two bromo-substituted dimers and the chloro-substituted dimer containing a hexamethylene spacer. The driving force for the formation of this phase is considered to be, at least in part, the specific anisotropic interaction between the unlike mesogenic units. The absence of smectic behaviour for the isosteric methyl-substituted dimers reveals that steric factors alone cannot stabilise the intercalated smectic A phase.     

Ionic-Liquid Salt-Mediated Synthesis of 4′-(Pyridyl)-terpyridines

One-pot reactions to produce isomeric 4′-(pyridyl) 2,2′:6′,2″-terpyridine under moderate conditions are described using imidazolium-based ionic liquid and quaternary ammonium-based molten salts as solvent media. The use of eutectic molten salts as a reaction media proved effective in sequential aldol and Michael addition reactions, leading to substituted terpyridines. The desired product was obtained in reasonable yield via a simple, one-pot reaction.     

Synthesis,characterization and in vitro antitumor behavior of a vanadium(V) complex with 4′-(3-methoxyphenyl)-2,2′:6′2″-terpyridine

A dioxovanadium(V) complex, [VO₂(moptpy)](ClO₄) (1, moptpy = 4′-(3-methoxyphenyl)2,2′:6′2″-terpyridine), was synthesized and characterized by elemental analysis, ESI-MS, UV–vis, IR, and ¹H, ¹³C, and ⁵¹V NMR. The cytotoxicity in vitro of 1 was evaluated against cancer cell lines HepG-2 (hepatocellular carcinoma), SGC-7901 (gastric carcinoma), SiHa (cervical cancer), BEL-7402 (hepatocellular), and rat PC-12 (pheochromocytoma) by the MTT method. The results demonstrated that 1 exhibits superior anticancer activity in vitro with much lower values of 50% inhibitive concentration (IC₅₀) against the selected cell lines than cisplatin, and 1 shows the highest cytotoxic activity toward SGC-7901 cells (IC₅₀ = 1.3 ± 0.1 μM) among the selected cell lines. A series of cellular morphological and staining experiments were carried out, and the results indicated that 1 can effectively induce apoptosis of SGC-7901 cells through a ROS-mediated mitochondrial dysfunction pathway. In addition, cellular incorporation and cell cycle analysis were also performed, and it was concluded from the experimental observations that 1 can efficiently enter into the cell nuclei, and the complex inhibits cell growth in SGC-7901 cell at G0/G1 phase.     

Synthesis of 2-(Substituted Benzylideneamino)-4-(4′-hydroxyphenyl) Thiazoles and Their O-Glucosides

2-Amino-4-(4′-hydroxyphenyl) thiazole 1a was prepared from reaction between p-hydroxyacetophenone, thiourea, and iodine; compound 1a was treated with several (aryl/hetro aryl) aldehydes to form 2-(substituted benzylideneamino)-4-(4′-hydroxyphenyl) thiazoles 2a–j, which were glucosylated by using acetobromoglucose as a glucosyl donor to afford 2-(substituted benzylideneamino)-4-(2, 3, 4, 6-tetera-o-acetyl-4′-o-β-d-glucosidoxyphenyl) thiazoles 3a–j, which further on during deacetylation produced 2-(substituted benzylideneamino)-4-(4′-o-β-d-glucosidoxyphenyl) thiazoles 4a–j. These compounds were evaluated for biological activity, and their structure was confirmed by IR, NMR, mass spectra, elemental, and chemical analysis.

     

Spectrophotometric study of the complexation equilibria of cobalt(II) with 4-(5′-methyl-3′-isoxazolylazo)-resorcinol and determination of cobalt(II)

The reaction of cobalt(II) with 4-(5′-methyl-3′-isoxazolylazo)-resorcinol (MIAR) in 4% v/v ethanol-water medium at I = 0.1 M (NaClO₄) was investigated spectrophotometrically. Graphical and numerical calculation methods were used to establish the equilibria in solution and to evaluate the stability constant of the complexes formed (log β₁₀₁ = 7.48±0.06, log β₁₁₁ = 12.77 max 12.99, log β₁₀₂ = 16.41±0.07). The optimum conditions for the spectrophotometric determination of Co(II) with MIAR were established and the method applied to its determination in some low alloy steels and hydrofining catalysts.     

Influence of Chiral 4-[(S)-2-Methyl-3-hydroxypropyloxy]-4′-cyanobiphenyl on the Properties of Liquid Crystalline Mixture on the Base of 4-Alkyloxy-4′-cyanobiphenyles

Russian Journal of General Chemistry - The formation of a chiral nematic mesophase by doping a liquid crystalline mixture of 4-alkyloxy-4′-cyanobiphenyls with chiral...     

Synthesis of (Z)-(2′R)-1-O-(2′-methoxynonadec-10′-enyl)-sn-glycerol,a new analog of bioactive ether lipids

An unsaturated 2-methoxy-substituted 1-O-alkylglycerol, (Z)-(2′R)-1-O-(2′-methoxynonadec-10′-enyl)-sn-glycerol, a new analog of bioactive ether lipids, was synthesized from oleic acid and 2,3-isopropylidene-sn-glycerol. The two key steps of this synthesis were the conversion of oleyl aldehyde to a monounsaturated epoxide using Matteson’s method followed by hydrolytic kinetic resolution and a nucleophilic epoxide opening by 2,3-isopropylidene-sn-glycerol in the presence of potassium tert-butoxide in anhydrous DMF, which appeared to be a good reagent for this purpose. Furthermore, the diol by-product of the HKR process was also easily converted back to the starting epoxide thus almost doubling the amount of target molecule.