Diels-alder reactions of 3, 6-diphenyl-1, 2, 4, 5-tetrazine and 3, 6-di(2-pyridyl)-1, 2, 4, 5-tetrazine with some 1-morpholinocycloalkenes

The reactions of 3, 6-diphenyl-1, 2, 4, 5-tetrazine 1 and 3, 6-di(2-pyridyl)-1, 2, 4, 5-tetrazine 2 with the enamines 3a-d derived from morpholine and the 5-,6-,7- and 8-membered cyclic ketones have been investigated. A number of pyridazine derivatives 4–7 most of which are new have been reported. Moreover, a novel procedure for the aromatization of pyridazines 5a-d to the corresponding pyridazine 7b-d via oxidative elimination using hydrogen peroxide is described. The structures of products 4–7 were confirmed by spectral methods and elemental analysis.     

Structures,electronic and magnetic properties of the FexNy (x = 1–4, y = 1–4) adsorbed graphene

Research on Chemical Intermediates - The structures, electronic and magnetic properties of the FexNy (x?=?1–4, y?=?1–4) molecules adsorbed graphene have been...     

Catalytic Cracking of Cyclohexane and 1-Hexene Mixtures on Mono-, Bi-, and Tri-Zeolite Catalysts

Kinetics and Catalysis - The effects of temperature (540–640°C), weight hour space velocity (1.0–7.0 h–1), and steam : raw material ratios (0–2.5) on the yield of...     

Synthesis,redox properties,and basicity of substituted 1-aminoanthraquinones: spectroscopic,electrochemical, and computational studies in acetonitrile solutions

1-Amino-, 1-ethylamino-, and 1-(diethylamino)-anthraquinone were characterized by UV–Vis spectroscopy, acid–base titration, electrochemical methods, and quantum-chemical (QM) calculations at the B3LYP/6-31 ++G^** level. Acid–base titration and the relative differences between the free energies of the basic and acidic forms of the studied species show that 1-(diethylamino)anthraquinone is the strongest base in an acetonitrile solution. Moreover, the structural differences between the B3LYP-optimized neutral and protonated anthraquinones, notably the presence or the absence of internal hydrogen bonds, account well for the sequence of the measured/calculated basicity. The basicity of the investigated compounds strongly influences their electrochemical properties in acetonitrile. Indeed, the cyclic voltammograms of 1-aminoanthraquinone and 1-(ethylamino)anthraquinone display two well-resolved reduction waves that indicate a two-step reduction process (EE mechanism). On the other hand, the electroreduction of 1-(diethylamino)anthraquinone becomes complicated by the interaction of its reduced forms with traces of water present in an acetonitrile solution (ECE mechanism). The mechanism of this reaction is proposed, and its possibility to occur is examined based on QM calculations.     

Synthesis of (1S,4R)-4-isopropyl-1-methyl-2-cyclohexen-1-ol,the aggregation pheromone of the ambrosia beetle Platypus quercivorus,its racemate, (1R,4R)- and (1S,4S)-isomers

(S)-Perillyl alcohol was converted to (R)-cryptone (91.5–93% ee) in six steps, which was then treated with methyllithium to give (1S,4R)-4-isopropyl-1-methyl-2-cyclohexen-1-ol, the aggregation pheromone of the ambrosia beetle Platypus quercivorus. The racemic pheromone was also prepared by methylation of (±)-cryptone. Both (1R,4R)- and (1S,4S)-isomers (98% ee) of the pheromone were synthesized from the enantiomers of dihydrolimonene oxide.     

New,simple, and efficient method for the synthesis of N-substituted 4-trifluoromethyl-5-(alkan-1-ol)-pyridin-2(1H)-imines

A new, simple, and efficient method for the synthesis a novel series of 1-substituted 4-(trifluoromethyl)-5-(alkan-1-ol)-pyridin-2(1H)-imines from the reaction of 3-(5,6-dihydro-4H-pyran-3-yl)-4,4,4-trifluorobut-2-enenitrile and 3-(4,5-dihydrofuran-3-yl)-4,4,4-trifluorobut-2-enenitrile with primary amines – is described. The products were obtained in 29–82% yield.     

Synthesis of highly active corticotropic (1-D-serine,17,18-dilysine)-beta-corticotropin-(1-18)-octadecapeptide amide

A synthesis is described of [1-D -serine, 17, 18-dilysine]-β-corticotropin-(1–18)-octadecapeptide amide (I), a short chain ACTH analogue which has been found to possess in animals and also in man high and prolonged corticotropic activity. Synthesis was carried out by the fragment condensation approach involving, in the last build-up step, coupling of the protected sequences 1–10 and 11–18. From the protected octadecapeptide derivative 1–18 the free peptide was obtained in high yield by acidolysis.     

Stereochemische Korrelationen zwischen (2R,4′R,8′R)-α-Tocopherol, (25S,26)-Dihydroxycholecalciferol, (–)-(1S,5R)-Frontalin und (–)-(R)-Linalol

Stereochemical Correlations between (2R,4′R,8′R)-α-Tocopherol, (25S,26)-Dihydroxycholecalciferol, (–)-(1S,5R)-Frontalin and (–)-(R)-Linalol The optically active C₅- and C₄-building units 1 and 2 with their hydroxy group at a asymmetric C-atom were transformed to (–)-(1S,5R)-Frontalin ( 7 ) and (–)-(3R)-Linalol ( 8 ) respectively; 1 and 2 had been used earlier in the preparation of the chroman part of (2R,4′R,8′R)-α-Tocopherol ( 6a , vitamin E), and for introduction of the side chain in (25S,26)-Dihydroxycholecalciferol ((25S)- 4 ), a natural metabolite of Vitamin D₃. The stereochemical correlations resulting from these converions fit into a coherent picture with those correlations already known from literature and they confirm our earlier stereochemical assignments. A stereochemical assignment concerning the C(25)-epimers of 25,26-Dihydroxycholecalciferol that was in contrast to our findings and that initiated the conversion of 1 and 2 to 7 resp. 8 for additional stereochemical correlations has been corrected in the meantime by the authors [26].     

A novel trinuclear titanium(IV) complex with a C3 axis along Ti1–Ti2–Ti3 containing 3-[(1H-1,2,4-triazol-1-yl)methyl]-BINOLate ligands: synthesis,structure, and reactivity

A new modified BINOL, (S)-3-[(1H-1,2,4-triazol-1-yl)methyl]-1,1′-binaphthol, was prepared. In the presence of titanium tetraisopropoxide, this ligand showed moderate catalytic properties for the asymmetric addition of diethylzinc to aldehydes. By treating rac-3-[(1H-1,2,4-triazol-1-yl)methyl]-1,1′-binaphthol with excess titanium tetraisopropoxide, a novel trinuclear titanium(IV) complex was obtained. A C₃ axis along Ti1–Ti2–Ti3 is present in the molecule.     

Synthesis,self-assembly and optical properties of novel fluorescent alkoxy-substituted fluoroaryl 1, 3, 4-oxadiazole organogelator

Aromatic nucleophilic substitution (S_NAr) reactions have been known to be regioselective to the para position on a variety of substituted perfluorobenzenes. In the current study, a series of fluoroaryl 1, 3, 4-oxadiazole derivatives substituted with different para terminal ethers were synthesized using S_NAr chemistry to afford fluorescent and thermally reversible low molecular weight organogelators (LMWOs). S_NAr was used to synthesize these highly fluorinated organogelators in high purity and good yields starting from pentafluorobenzoic acid and 4′-hydroxy-4-biphenylcarbonitrile. These fluorinated 1, 3, 4-oxadiazole derivatives were characterized by elemental analysis, FTIR, and ¹H, ¹³C, and ¹⁹F NMR spectroscopy. The photophysical properties of those organogelators were described. Both UV–visible absorption and fluorescence spectral profiles displayed a solvatochromic and solvatofluorochromic properties. The absorption maxima for the developed organogelators were monitored in the range of 260–289 nm, whereas the emission maxima were monitored in the range of 278–305 nm. The best gelation properties were monitored for the hexyloxy-substituted 2-(biphenylyl)-5-(perflurophenyl)-1, 3, 4-oxadiazole gelator in different solvents with critical gel concentrations in the range of 1.86–5.07 mM. The self-assembly process was monitored to occur via van der Waals forces and π-π stacks to result in gelation of solvents. Scanning electron microscope (SEM) demonstrated nanofiber-like structures (350–550 nm). The thermal stability of the hexyloxy-substituted organogel was monitored at 48 °C. Both cytotoxicity and antimicrobial activity of the produced fluoroaryl 1, 3, 4-oxadiazole derivatives were explored to verify their potential use for biomedical applications, such as drug delivery and bioimaging.     

Synthesis,characterization, crystal structure and DFT studies on 3-(1H-benzo[d][1,2,3]triazol-1-yl)-1-(4-ethylphenyl)-1-oxopropan-2-yl-4-ethylbenzoate

3-(1H-benzo[d][1,2,3]triazol-1-yl)-1-(4-ethylphenyl)-1-oxopropan-2-yl-4-ethyl-benzoate (BEOE) has been synthesized and characterized by elemental analysis, IR, UV–vis and fluorescence spectroscopy. Its crystal structure has also been determined by X-ray single crystal diffraction. For the title compound, density functional theory (DFT) calculations of the structure and vibrational frequencies have been performed at B3LYP/6-31G* level of theory. Based on the vibration analysis, thermodynamic properties of the title compound have been calculated. The correlative equations between the thermodynamic properties and temperatures have also been listed. By using TD-DFT method, electron spectra of the title compound have been predicted, which suggests the B3LYP/6-31G* method can approximately simulate the electron spectra for the system presented here.     

Self-assembly of three Cd(II) complexes: 0-D, 1-D,and 3-D structures based on 2-(1H-imidazol-1-methyl)-1 H-benzimidazole

Three new complexes, [Cd(L)I₂]₂ (1), {[Cd(L)I₂]?·?DMF} _n (2), and [Cd₂(L)₄(μ ₂-I)I(H₂O)] _n (3), have been obtained through self-assembly of an unsymmetrical ligand 2-(1H-imidazol-1-methyl)-1H-benzimidazole (L) with Cd(II) salts. Single-crystal X-ray diffraction shows that 1 displays a dimeric structure in which two Cd(II) ions are bridged by two bidentate bridging L. Complex 2 exhibits a 1-D chain structure (···Cd–L–Cd–L···) constructed by L bridging Cd(II) ions. In 3, the Cd(II) ions are five-connected nodes and linked by L and iodide leading to the 3-D network. Complexes 2 and 3 are synthesized maintaining the same solvents and stoichiometric ratio of metal and ligand at different reaction temperature. The different structures of the complexes indicate that the temperature plays a significant role in construction of the complexes. Luminescent properties of 1–3 have been investigated in the solid state at room temperature.     

Synthesis,characterization, and antimicrobial activity of novel (<Emphasis Type="Italic">E</Emphasis>)-1-(aryl)-3-{3, 5-dimethoxy-4-[(1-(aryl)-1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazol-4-yl)methoxy]phenyl}prop-2-en-1-ones

The new chalcone derivatives containing the 1,2,3-triazole ring system, namely, (E)-1-(aryl)-3-{3,5-dimethoxy-4-[(1-(aryl)-1H-1,2,3-triazol-4-yl)methoxy]phenyl}prop-2-en-1-ones, were synthesized in 65–88% yield by the “click chemistry” reactions of substituted acetophenones, 4-hydroxy-3,5-dimethoxy-benzaldehyde, and different substituted azides. The structure of the compounds was determined by the FT-IR, ¹H NMR, ¹³C NMR, and mass spectroscopic analyses. Compounds 6a–6l were screened for in vitro antimicrobial activity by the agar disc diffusion method.     

Hydrogen-bonding network in the crystal of bis[1-(diaminomethylene)thiouron-1-ium] oxalate

The single crystals of bis[1-(diaminomethylene)thiouron-1-ium] oxalate were grown using a solution growth technique. The compound crystallises in the centrosymmetric C2/c space group of the monoclinic system. The conformation of the 1-(diaminomethylene)thiouron-1-ium cation is not strictly planar, but twisted. Both arms of the cation are oppositely rotated by 5.0(1)° around the C–N bonds involving the central N atom. The centrosymmetric oxalate(2-) anion is planar. The arrangement of oppositely charged components, i.e. 1-(diaminomethylene)thiouron-1-ium cations and oxalate(2-) anions in the crystal is mainly determined by ionic and hydrogen bonding interactions forming three-dimensional network. The compound was also characterised by the FT-IR and Raman spectroscopy. The characteristic bands of the NH₂, CS and COO^? groups as well as of C–N–C, N–C–N and C–COO skeletal groups are discussed.     

Calorimetric study of thermodynamics of production of polybutene-1, polypentene-1, 4-methylpentene-1 and properties of reagents between 0 and 670 K

The heat capacitiesC ₀ ^p of polybutene-1, polypentene-1, poly-4-methylpentene-1 and 4-methylphentene-1 were studied calorimetrically from 6 to (500–700) K. Temperatures, enthalpies of melting of various crystalline forms and the parameters of the glass transition were determined. The thermodynamic functionsH ⁰(T)?H⁰(0), S⁰(T) andG ⁰(T)?H⁰ (0) were calculated between 0 K and (500–700) K. From the calorimetric values obtained and literature data, the thermodynamic characteristics of the following processes were estimated for the corresponding alkenes-1, andcis-andtrans-alkenes-2: the polymerization of alkenes-1, the monomer-isomerization polymerization ofcis- andtrans-alkenes-2 to polyaklenes-1 and the isomerization ofcis- andtrans-aklenes-2 to alkenes-1 in the same temperature interval at standard pressure.     

Vinyl Ethers Containing an Epoxy Group: XXIII. Reactions of Alkynylmagnesium Bromides with Glycidol Ethers: Synthesis and Thermal Transformations of 1-[2-( Vinyloxy)ethoxy]- and 1-(Allyloxy)-5-hexyn-2-ols, -5-phenyl-4-pentyn-2-ols,and -3-bromo-2-propanols

Reaction of 2-[2-(vinyloxy)ethoxy]methyl- and 2-(allyloxymethyl)oxiranes with 2-propynyl- and phenylethynylmagnesium bromides (10–55°C, 0.5–4 h) resulted in new representatives of the series of 1-organyloxy-5-hexyn-2-ols, -5-phenyl-4-pentyn-2-ols, and -3-bromo-2-propanols in 50–99% yields. During distillation the 1-[2(vinyloxy)ethoxy]-5-phenyl-4-pentyn-2-ol and -3-bromo-2-propanol transform respectively into 2-methyl-4-(3-phenyl-2-propynyl)- and 2-methyl-4-(bromomethyl)-1,3,6-trioxocanes via intramolecular cyclization involving the hydroxy and vinyloxy groups.     

Synthesis and Properties of Ethyl [(Adamantan-1-yl)alkylene(phenylene)amino]oxoacetates and N1,N2-Bis[(adamantan-1-yl)alkylene(phenylene)]oxamides

Russian Journal of Organic Chemistry - Ethyl [(adamantan-1-yl)alkylene(phenylene)amino]oxoacetates and N1,N2-bis[(adamantan-1-yl)-alkylene(phenylene)oxamides were prepared in yields of 72–87...     

1-(N-Acylamino)-1-triphenylphosphoniumalkylphosphonates: General synthesis and prospects for further synthetic applications

A general approach for the synthesis of 1-(N-acylamino)-1-triphenylphosphoniumalkylphosphonates from readily accessible alkyl imidate hydrochlorides has been developed. The three-step synthesis involves acylation of the imidate hydrochloride with an acyl chloride, the Michaelis–Becker-like addition of diethyl phosphite to the N–acylimidate and subsequent nucleophilic substitution of the ethoxy group of the 1–ethoxyphosphonate derivative with triphenylphosphonium tetrafluoroborate. 1–(N–Acylamino)-1-triphenylphosphoniumalkylphosphonates were demonstrated to be promising intermediates for further synthetic transformations toward α-functionalized derivatives of α–aminophosphonic acids and α,β-dehydro-α-aminophosphonates.     

Preparation and mesomorphic properties of 1-methyl-1H-benzimidazole-based compounds

A series of 1-methyl-1H-benzimidazole-based compounds, 2-(4?-alkoxy-1,1?-biphenyl-4-yl)-1-methyl- 1H-1,3-benzimidazole derivatives (nPPMx-M) with terminal hydrogen, methyl and nitro moieties (coded as nPPMH-M, nPPMM-M and nPPMN-M, respectively), were prepared and their structures were characterised. The compounds display enantiotropic smectic mesophases for hydrogen and methyl terminated compounds (nPPMH-M and nPPMM-M), and enantiotropic nematic mesophases for nitro terminated compounds (nPPMN-M) with short alkoxy chain below than 10 carbon atoms, where the mesophase ranges are 24–72°C and 74–104°C on heating and cooling processes for nPPMH-M, 90–119°C and 110–135°C for nPPMM-M, and 102–129°C and 113–207°C for nPPMN-M, respectively. It is noted that the compounds nPPMx-M exhibit much lower melting points and much wider mesophase range both in heating and cooling than non-1-methyl substituted analogs, which are ascribed to the disruption of hydrogen bonding among the molecules caused by methyl substitution at 1-position of benzimidazole. Meanwhile, among the compounds nPPMx-M, much wider mesophase ranges are obtained for nPPMM-M and nPPMN-M, indicating a much high mesophase stability for the compounds bearing terminal moiety (CH₃ and NO₂).