Compensation effect in the electrical conduction process in a series of pyrenyl polyenes

The semiconductive properties of a series of pyrenyl polyenes of the type R-(CH=CH)_n-R, are studied as a function of the adsorption of different amount of a vapour. With regard to the compensation temperature (T ₀) the compounds are divided into two groups. For compounds which have odd number of double bonds,T ₀ is infinite and in compounds having even number double bonds,T ₀ is finite.T ₀ for II₂ is higher while that of II₄ is lower than the experimental temperature. DifferentT ₀ for the compounds having odd or even number of double bonds suggests a physical basis for the compensation rule, which we believe, is related to the molecular and crystalline structure of the compounds     

Mass spectra of some α-substituted phenyl-α,α′-dimethoxyl ketones and their derivatives

The mass spectra of some α-substituted phenyl-α,α′-dimethoxyl ketones (compounds 1) and their 2,4-dinitrophenylhydrazones (compounds 2) and semicarbazones (compounds 3) have been studied. The characteristic fragments at m/z (M ? 73) from compounds 1, m/z (M ? 253) from compounds 2 and m/z (M ? 130) from compounds 3 are abundant and proposed to be [ArCROCH₃]⁺. Fragmentations yielding [M⁺ ? 49] from compounds 2 are abnormal and probably involve the methoxyl and nitro groups. The intense peak at m/z 130 due to [CH₃OCH₂CNNHCONH₂]⁺ from compounds 3 corresponds to α-cleavage of the molecular ion. Some other fragments from these new compounds are interpreted in this paper.     

Phytochemical,cytotoxic and chemotaxonomic study on Ajuga forrestii Diels (Labiatae)

A phytochemical investigation of Ajuga forrestii Diels led to the isolation of 14 compounds, including eight neo-clerodane diterpenes (1–8), two phytoecdysteroids (9, 11), one stigmastane sterol (10) and three iridoid glycosides (12–14). The structures of these compounds were identified by spectroscopic methods and a comparison of their data with those reported in the literature. This is the first report of compounds 1–14 from A. forrestii. The cytotoxic activities of the aqueous extract of A. forrestii and several compounds have been studied and the chemotaxonomic significance of isolated compounds has also been summarised.     

Synthesis and in vitro Study of Novel Methylenebis(phenyl- 1,5-benzothiazepine)s and Methylenebis(benzofuryl-1,5- benzothiazepine)s as Antimicrobial Agents

A series of methylenebis(phenyl-1,5-benzothiazepine)s 4 and methylenebis(benzofuryl-1,5-benzothiazepine)s 5 were prepared by the reaction of methylene-bis-chalcones 3 with 2-aminothiophenol for 4 and followed by the condensation with chloroacetone for 5. The structures of the synthesized compounds have been confirmed by their IR, 1H NMR, 13C NMR, MS and elemental analyses. All the synthesized compounds were tested for their antimicrobial activity against Gram-positive, Gram-negative bacteria and fungi. To elucidate the essential structural requirements for the antimicrobial activity, the preliminary structure-activity relationship has been described. Among the compounds tested, the dimeric compounds 4f, 4g, 5f and 5g were found to be most active against Bacillus subtilis, Bacillus sphaericus, Staphylococcus aureus, Klebsiella aerogenes and Chromobacterium violaceum. Similarly these dimeric compounds showed potent antifungal activity against Candida albicans, Aspergillus fumigatus, Trichophyton rubrum, and Trichophyton mentagrophytes. It is interesting to note that the dimeric compounds with substituents of heterocyclic ring at the 4th position of benzothiazepine system displayed notable antibacterial activity equal to that of streptomycin and penicillin. Further, the activity of all the dimeric compounds was compared with that of their monomeric compounds, and it is interesting to note that almost all the dimeric compounds showed enhanced activity than their monomeric compounds.     

HPLC Fingerprint Characteristics of Active Materials of Garlic and Other Allium Species

The bioactive molecules of garlic are classified according to their enzymatic activities as either alliinase activators or alliinase inactivators. The alliinase activation reaction system is mainly composed of sulfur-containing compounds, whereas the alliinase inactivation system is mainly composed of amino acid-based materials. The purpose of this study was to develop an effective way to digitally express features of complex active compounds of garlic as a basis for quality control. HPLC was used to develop the fingerprints of plants from different Allium species and different geographical regions according to whether the compounds were sulfur containing or based on amino acids. Using the Shannon equation, I values of sulfur-containing compounds from garlic ranged from 3.55 to 3.94, whereas I values of sulfur-containing compounds from other Allium plants, onions, leek, and Welsh onion, ranged from 3.38 to 3.53. The I values of amino acid-based compounds from garlic ranged from 3.67 to 3.91, whereas I values of these compounds from other Allium plants ranged from 3.88 to 3.99. This method effectively distinguished garlic from different species of Allium plants. This method also provided a way to digitally monitor the presence of complex active compounds of garlic and may allow evaluation of quality. This method may also provide a theoretical basis for quality control of bioactive compounds from other medicinal plants.     

Chemical constituents from Epimedium koreanum Nakai and their chemotaxonomic significance

In this study, 21 compounds were isolated from the aerial parts of Epimedium koreanum Nakai, including 6 phenols (1–5 and 10), 4 lignans (6–9) and 11 flavonoids (11–21). The chemical structures of those isolates were established after extensive one-and two-dimensional nuclear magnetic resonance and mass spectroscopy analyses. This is the first report of compounds 2, 3, 4 and 9 in E. koreanum and of compounds 5 and 7 in the family Berberidaceae. The chemotaxonomic significance of the isolated compounds is discussed.     

Calculation of 1H chemical shifts of [n]annuleno[m]annulenes and [n]annulenyl[m]annulenes

The ring current and local anisotropic contributions to the ¹H chemical shifts of [n]annuleno[m]annulenes and [n]annulenyl[m]annulenes with n, m = 12, 14, 18 and n, m = 13, 15 are calculated. The agreement between experimental and calculated shifts for the few known compounds is very good so that the predictions for the as yet unknown compounds are reliable. The effect of an annulene ring on the shifts of the protons at the other ring in these bicyclic compounds is discussed for several types of fusion of the two constituent annulenes.     

An efficient in situ reduction and cyclization reaction for synthesis of spiro compound derivatives in Fe–H2O–AcOH medium from nitro compounds

An efficient in situ reduction and cyclization reaction for the synthesis of nitrogen‐containing spiro compounds directly form 5‐nitro‐1H‐indazole, 6‐nitro‐1H‐indazole and 5‐nitroindole in Fe–H₂O–AcOH medium is reported. 5‐Nitro‐1H‐indazole, 6‐nitro‐1H‐indazole and 5‐nitroindole were first used to synthesize spiro compounds, and this is a novel method for the synthesis of spiro compounds from nitro compounds. The advantages of this reaction are stable reagents, easily available raw materials, wide range of substrates and high yields.     

A new procedure for the cyclization of 2-indole- and 3-indolecarbohydrazones to 5H-pyridazino[4,5-b]indole derivatives

A new procedure for the cyclization of 2-indolecarbohydrazones (5) to 1,2,3,4-tetrahydro-4-oxo-5H-pyridazino[4,5-b]indoles (6) and for the cyclization of 3-indolecarbohydrazones (7) to 1-oxo-1,2,3,4-tetrahydro-5H-pyridazino[4,5-b]indoles (8 and 9) is described. The hydrazones (5 or 7) were treated with an acyl halide (acetyl or benzoyl chlorides) and triethylamine in ethyl acetate of chloroform as solvents to give the compounds 6 (20–70%) from the compounds 5 , and the compounds 8 (20–60%) from the compounds 7 . Through refluxing with ethanol-hydrochloric acid the compounds 8a-8f selectively separate the acetyl group on N⁵ to give the respective compounds, 9a-9f. The ir and ¹H-nmr spectra of all the compounds 5, 6, 7, 8 and 9 and the uv, mass and ¹³C-nmr spectra of the compounds 7h, 7i, 8h and 8i are discussed.     

Cr concentration driving the structural,mechanical, and thermodynamic properties of Cr-Al compounds from first-principles calculations

Cr-Al binary compounds are regarded as the potential high-temperature structural materials. However, the structure and important properties of Cr-Al compounds are not completely unclear. Here, we report on the influence of Cr concentration on the structural, mechanical, and thermodynamic properties of Cr-Al compounds by using the first-principles calculations. Four novel Cr-Al compounds, Cr₃Al₈ with monoclinic structure (C2/m), Cr₃Al₅ with hexagonal structure (P63mc), Cr₂Al₃ with tetragonal structure (I4/mmm), and Cr₃Al with cubic structure (Pm-3 m), are predicted. The calculated elastic modulus of Cr-Al compounds gradually increases with increasing Cr concentration. Compared to other Cr-Al compounds, our predicted Cr₃Al with cubic structure exhibits a strong deformation resistance and high hardness due to symmetrical Cr Al bonds. However, the Debye temperature of Cr₇Al₃ is larger than that of other Cr-Al compounds. The calculated phonon density of state shows that the high-temperature thermodynamic properties of Cr-Al compounds are attributed to the vibration of Al atom and Cr Al bond.     

Using the QSPR Approach for Estimating the Density of Azole‐based Energetic Compounds

The relationship between density of energetic azole‐based compounds and their molecular structure is investigated through quantitative structure‐property relationship (QSPR) approach. The methodology of this work introduces a new model, which related density of azole‐based energetic compounds to the optimum elemental composition, the degree of unsaturation (DoU) of the compounds, presence of nitroimino group in the structural formula, as well as several non‐additive structural parameters. The presence of nitroimino functional group and also increasing the value of n_O/n_N in the formula of these compounds can enhance their density. The correlation is derived on the basis of experimental density values of 100 azole‐based energetic compounds with different molecular structure as training set. The determination coefficient of the new correlation is 0.923. Also, it has the root mean square deviation (RMSD) and the average absolute deviation (AAD) of 0.038 and 0.030 g · cm^–3, respectively. In addition, the correlation gives good predictions for further 25 azole‐based energetic compounds as test set (Q²_EXT = 0.901). The predictive ability of the correlation is checked using a cross validation method (Q²_LMO = 0.918). The proposed method can also apply for designing novel azole‐based energetic compounds.     

Chemical reactivity of hypervalent silicon compounds: The local hard and soft acids and bases principle viewpoint

The silicon atom may increase its coordination number to values greater than four, to form pentacoordinated compounds. It has been observed experimentally that, in general, pentacoordinated compounds show greater reactivity than tetracoordinated compounds. In this work, density functional theory is used to calculate the global softness and the condensed softness of the silicon atom for SiH _n F_4−n and SiH _n F _5−n ¹⁻ . The values obtained show that the global and condensed softness are greater in the pentacoordinated compounds than in the tetracoordinated compounds, a result that explains the enhanced reactivity. If the results are analysed through a local version of the hard and soft acids and bases principle, it is possible to suggest that in nucleophilic substitution reactions, soft nucleophiles preferably react with SiH _n F _5−n ¹⁻ , and hard nucleophiles with SiH _n F_4−n .     

1H‐4,5,6,7‐tetrahydro‐1,3‐diazepines. Part I: Synthesis,spectral and chemical properties of 1,2‐diaryl derivatives

The synthesis of several 1,2‐diaryl‐1H‐4,5,6,7‐tetrahydro‐1,3‐diazepines 1 by cyclization of N‐aryl‐N'‐benzoyltetramethylenediamines 2 is described. Two alternative synthetic routes to obtain precursors 2 are discussed, being that which employes pyrrolidine as starting material the most convenient. Nucleophilic attack of compounds 1 on methyl iodide affords 1,2‐diaryl‐1H‐4,5,6,7‐tetrahydro‐1,3‐diazepinium iodides 3 . ¹H‐nmr spectra of these compounds are unequivocally assigned by means of NOESY experiments, ¹H‐nmr spectra of compounds 1 and 3 are analyzed and compared inter se and with those of compounds 1 run in the presence of trifluoroacetic acid‐d. Reduction of compounds 1 with borane leads regiospecifically to N‐aralkyl‐N'‐aryltetramethylenediamines 7 .     

Vicinal 13CH coupling through olefinic double bonds

Values of long range ¹³CH coupling through the double bond in a number of isopropenyl compounds are reported. There is evidence that substituent dependence of ³J(CH) is not related linearly to that of H? H couplings in vinyl compounds. The ratio of ³J(CH) to ³J(HH) in analogous pairs of compounds appears to increase with decreasing substituent polarity and increasing steric bulk.     

Four new compounds from Neoboletus magnificus

Abstract

Four new compounds, compounds 1, 2, 4, 6, along with two known compounds 3, 5, were isolated from the methanol extract of the fruiting body of Neoboletus magnificus. The structures of compounds were elucidated by HRMS and NMR spectroscopic methods. The in vitro anti-inflammatory activity of the isolated compounds was evaluated.     

‘Click Synthesis’ of Some Novel Benzimidazol Oxime Ethers Containing Heterocycle Residues as Potential ß‐Adrenergic Blocking Agents

The ‘click synthesis’ of some novel O‐substituted oximes, 5a – 5j , which contain heterocycle residues, as new analogs of ß‐adrenoceptor antagonists is described (Scheme 1). The synthesis of these compounds was achieved in four steps. The formation of (E)‐2‐(1H‐benzo[d]imidazol‐1‐yl)‐1‐phenylethanone oxime, followed by their reaction with 2‐(chloromethyl)oxirane, afforded mixture of oil compounds 3 and 4 , which by a subsequent tetra‐n‐butylammonium bromide (TBAB)‐catalyzed reaction with N H heterocycle compounds (Scheme 1), led to the target compounds 5a – 5j in good yields.     

Reaction of N,N'-dialkyldithiodianilines with β-ketoesters. A new synthesis of N-alkyl-2-acyl-3-oxo-3,4-dihydro-1,4-benzothiazines

The title compounds 3a-j together with the N-alkylacylketene S,N-acetals 12a-j were obtained by reaction of N,N'-dialkyldithiodianilines with β-ketoesters compounds. A possible reaction pathway is suggested.     

Nitrostyrene Derivatives of Adenosine 5′-Glutarates Modified with an Alkyl Spacer and their inhibitory activity on epidermal growth factor receptor protein tyrosine kinase

β-Nitrostyrene derivatives of adenosine 5′-glutarates are potent and selective bisubstrate-type inhibitors of the epidermal growth factor receptor protein tyrosine kinase (EGF-R PTK). In an attempt to improve the inhibitory activity, this type of compounds was modified with alkyl spacers of varying length between the nitrostyrene and the glutaryl units. The spacers consisted of 1, 3, 4, and 5 atoms to give compounds of the benzyl, oxyethyl, oxypropyl, and oxybutyl series, respectively (Schemes 1 and 2). Adenosine 5′-esters were prepared in the benzyl and oxypropyl series only. Compared to the compounds in the parent series without spacer (IC₅₀ = 0.7–12 μM ), most of the modified compounds inhibited the EGF-R PTK only marginally or were inactive (IC₅₀ ≥ 100 μM ). The only exceptions were the free acids 19 and 20 with IC₅₀ values of ca. 5 μM . It is noteworthy that esterification of these two hydrogen glutarates with either MeOH or adenosine yielded inactive compounds, which is in contrast to the corresponding substances without spacers.     

Selective detection of unknown organic bromine compounds and quantification potentiality by negative-ion electrospray ionization mass spectrometry with induced in-source fragmentation

For the detection of unknown organic bromine compounds, a liquid chromatography–mass spectrometry (LC-MS) method with negative-ion electrospray ionization (NI-ESI) and induced in-source fragmentation (IISF) was established. After LC separation, the molecules are fragmentized in the source, and bromide is detected via m/z 79 and m/z 81 based on the isotopic occurrence of bromine. In this way, the retention times of the unknown organobromine compounds are determined, and this can be used to extract additional structural information (number of bound bromine atoms, molecular mass and fragmentation scheme) from measurements in the commonly used but less sensitive scan mode. The analysis of known organobromine compounds shows that LC/NI-ESI-IISF mass spectrometry with detection of m/z 79 and 81 is more sensitive than the detection of daughter ions (LC/ESI/MS-MS). Therefore, we present a method not only for the detection of unknown organic bromine compounds, but also for the selective and sensitive detection and quantification of known organobromine compounds.     

Quinazolines and 1,4-benzodiazepines LVII. 1H-1,4-benzodiazepines

The preparation of the title compounds 3 and 4 using two different methods of synthesis is described. These compounds are readily reduced to 2,3-dihydro-1H-derivatives 5 . Oxidation of 2-alkylthio-1H-1,4-benzodiazepines leads to the corresponding sulfoxides and sulfones. The oxidative rearrangement of sulfones 9 to a 2H-1,4-benzodiazepin-2-one derivative 10 is also given. The “normal” addition of azodicarboxylate together with an unusual addition of two moles of acetylenedicarboxylate to the enamine double bond of 1H compounds is discussed.