Synthesis, characterization, and biological evaluation of new oxime-phosphazenes

Hexachlorocylotriphosphazene (1) was reacted with 4-hydroxy-3-methoxybenzaldehyde to give hexakis[(4-formyl-2-methoxy)phenoxy]cyclotriphosphazene (2). Hexakis[(4-(hydroxyimino)2-methoxy)phenoxy]cyclotriphosphazene (3) was synthesized by reaction of 2 with hydroxlamine hydrochloride in pyridine. Compound 3 was reacted with benzyl chloride, acetyl chloride, allyl bromide, benzoyl chloride, propanoyl chloride, 4-methoxybenzoyl chloride, 2-chlorobenzoyl chloride, chloroacetyl chloride, methyl iodide, and thiophene-2-carbonyl chloride. From these reactions, full or partially substituted compounds were obtained, usually in high yields. Pure or defined products could not be obtained from reaction of 3 with methacryloyl chloride and O-acetylsalicyloyl chloride. The structures of the compounds were determined by elemental analysis, and IR, ¹H, ¹³C, and ³¹P NMR spectroscopy. The synthesized compounds were screened for in-vitro antimicrobial activity against two Gram-positive bacteria (Staphylococcus aureus and Enterococcus faecalis), two gram-negative bacteria (Escherichia coli and Klebsiella pneumonia), and fungal strains (Aspergillus niger, and Candida albicans) by the agar well diffusion method. Few compounds had significant activity against both Gram-positive and Gram-negative bacteria. None of the compounds had antifungal activity except compounds 7 and 9, which had moderate activity.     

Synthesis and structural characterization of geminal and non-geminal 1,1,3,3-tetramethylguanidine substituted derivatives of cyclotriphosphazene: Thermal and spectroscopic investigations of the products

Abstract

The reactions of hexachlorocyclotriphosphazene, N₃P₃Cl₆ (1) with 1,1,3,3-tetramethyl-guanidine (2) in (1:1:2, 1:2:4 and 1:3:6) stoichiometries in THF and dichloromethane solutions under reflux yield a total of 4 novel products: three non-geminal derivatives, N₃P₃Cl₄[NCN₂(CH₃)₄]₂ (3), N₃P₃Cl₃[NCN₂(CH₃)₄]₃ (4) and N₃P₃Cl₂[NCN₂(CH₃)₄]₄ (5); and one hexa-substituted product, N₃P₃[NCN₂(CH₃)₄]₆ (6). The structures of 3-6 have been determined mainly by elemental analysis, MS, ³¹P and ¹H NMR spectral data. Furthermore, thermal characteristics of the synthesized compounds 4 and 6 were evaluated using Differential Scanning Calorimetric (DSC) measurements. NMR spectroscopic data, product types and relative yields are compared with those of the previously investigated derivatives of N₃P₃Cl₆ (1) with mono and difunctional reagents.     

Synthesis and cytotoxicity studies of methoxy benzyl substituted titanocenes

From the reaction of 6(2-methoxy-phenyl)fulvene (1a), 6(3-methoxy-phenyl)fulvene (1b), 6(3,4-dimethoxy-phenyl)fulvene (1c) and 6(3,4,5-trimethoxy-phenyl)fulvene (1d) with LiBEt₃H, lithiated cyclopentadienide intermediates 2a-d were synthesised. These intermediates were then transmetallated to titanium with TiCl₄ to give benzyl substituted titanocenes bis-[(2-methoxy-benzyl)cyclopentadienyl]titanium(IV) dichloride (3a), bis-[(3-methoxy-benzyl)cyclopentadienyl]titanium(IV) dichloride (3b), bis-[(3,4-dimethoxy-benzyl)cyclopentadienyl]titanium(IV) dichloride (3c) and bis-[(3,4,5-trimethoxy-benzyl)cyclopentadienyl]titanium(IV) dichloride (3d). The three titanocenes 3a-c were characterised by single crystal X-ray diffraction, while the structure of the fourth titanocene 3d was elucidated through a DFT calculation. All four titanocenes had their cytotoxicity investigated through preliminary in vitro testing on the LLC-PK (pig kidney epithelial) cell line in order to determine their IC₅₀ values. Titanocenes 3a-d were found to have IC₅₀ values of 97, 159, 88 and 253 μM, respectively. All four titanocene derivatives show significant cytotoxicity improvement when compared to unsubstituted titanocene dichloride.     

取代苄基五甲氧羰基环戊二烯的合成和晶体结构

五甲氧羰基环戊二烯基钾和取代苄基卤化物反应, 合成了七个新型苄基取代五甲氧羰基环戊二烯。由^1H NMR、IR、元素分析等确认R(苄基)和环戊二烯上碳直接相连, 具有典型的碳碳连结。对产物之一, 1-萘亚甲基五甲氧羰基环戊二烯的X射线衍射测定, 进一步肯定了上述结论。化合物为单斜晶系, 空间群为P2/n, a=0.9731(1), b=1.7403(3), c=1.465(3)nm; β=95.70(1)^°, v=2.4712nm^3, D~c=1.334g/cm^3, 最终的R=0.093, 萘亚甲基环与环戊二烯基环的二面角为68.19^°。     

Synthesis of benzyl substituted naphthalenes from benzylidene tetralones

A convenient and efficient synthesis of novel highly substituted dimethoxybenzylnaphthalenes, which are precursors to several dihydroxynaphthoic acids, is described. The approach involves the use of aldol chemistry to provide a number of benzylidene tetralones, which are converted to the target naphthalenes in three steps, with good to excellent yields. Grignard reaction of intermediate benzyl tetralones provided 1-substituted benzyl naphthalenes. The reported synthesis is flexible and scalable and provides access to naphthalenes having a variety of substitution patterns. These benzyl substituted naphthalenes are being converted to naphthoic acids and the bioactivities of these compounds are currently being investigated.     

Synthesis and characterization of some new mononuclear ruthenium complexes containing 4-(un)substituted dipyridylpyrazole ligands

A mononuclear ruthenium complex [Ru(bpy)₂(bpp)](PF₆) (1) and its halogenated and nitro derivatives [Ru(bpy)₂(Xbpp)](PF₆) (bpy = 2,2′-bipyridine; bpp = 3,5-bis(2-pyridyl)pyrazole; X = Cl, 2; X = Br, 3; X = I, 4; X = NO₂, 5) have been synthesized and characterized by ¹H NMR, ¹³C NMR, HRMS, elemental analysis. Complexes 2–5 have been further confirmed by X-ray diffraction. Their UV–Vis and emission spectroscopies, electrochemical measurements and acid–base properties are described. The results presented here reveal that the introduction of Cl, Br, I and NO₂ groups to the coordinated bpp⁻ ligand makes the absorption and emission maxima of the parent complex 1 blue-shifted, the oxidation potential of the Ru^II/Ru^III couple increased and the pK_a value decreased obviously. In addition, significant quenching of the emission by these groups is also observed.     

Synthesis of substituted 2,5-diazabicyclo[2.2.1]heptanes

A new method is proposed for the synthesis of substitituted 2,5-diazabicyclo[2.2.1]heptanes from 1-(tert-butoxycarbonyl)-4-tosyloxy-2-(tosyloxymethyl)pyrrolidine.¹H NMR spectroscopy indicated multiple conformations of 2-(tert-butoxycarbonyl)-2,5-diazabicyclo[2.2.1]heptanes in solution.St. Petersburg State University, 198904 St. Petersburg, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 501–503, April, 2000.     

Synthesis,spectroscopic/electrochemical characterization and DNA interaction study of novel ferrocenyl‐substituted porphyrins

We report the synthesis and characterization of two new meso‐ferrocenylporphyrins, with the ferrocenyl unit attached at the para position of a C₆F₄ group by a C? N bond with ? NH(CH₂)₂NH? ( 2a ) and ? NH(CH₂)₄NH? ( 2b ) spacers. Compounds 2a and 2b were characterized through elemental analyses, electrospray ionization high‐resolution mass spectrometry, ¹H NMR, UV–visible and fluorescence spectroscopies, electrochemistry and spectroelectrochemistry. The free base porphyrin 2 was included for comparison purposes. The binding ability of 2 and the porphyrin derivatives 2a and 2b with calf thymus DNA was determined using UV–visible and fluorescence spectroscopies. The results suggest that the interaction of these systems most probably occurs through π‐stacking by non‐classical modes involving the partial insertion of the C₆F₅ ring between adjacent base pairs on DNA and possible hydrogen interaction with the aliphatic ? NH(CH₂)_nNH? (n = 2 or 4) groups with calf thymus DNA. Moreover, we also demonstrate that porphyrins generate singlet oxygen species and show good photostability after irradiation.     

Comparative study of the reactivities of substituted 3-(benzoyl)benzyl carbanions in water and in DMSO

Benzyl-substituted carbanions produced by photodecarboxylation of ketoprofen derivatives have been examined in basic aqueous and DMSO solutions. Product studies, combined with kinetic measurements from laser flash photolysis, have allowed the determination of absolute rate constants for protonation and intra-S(N)2 reactions leading to five- and six-membered ring cyclizations; the former are significantly faster. Many of the well-known trends in carbanion reactivity are placed on an absolute rate basis; thus, intra-S(N)2 are favored in polar nonprotic solvents, and the effect is larger for the more hindered carbanion centers. Protonation by water is slightly dependent on the nature of the carbanion center and is approximately 400 times faster in nonhydroxylic solvents, compared with bulk water. As expected, the reactivity for halide leaving groups follows the usual order of decreasing bond strengths, i.e., I(-) > Br(-) > Cl(-).     

Synthesis, characterization, and thermal stability of star-shaped poly(ε-caprolactone) with phosphazene core

Hexakis[p-(hydroxylmethyl)phenoxy]cyclotriphosphazene was synthesized by the reaction of hexachlorocyclotriphosphazene with the sodium salt of 4-hydroxybenzaldehyde and subsequent reduction of aldehyde groups to alcohol groups by using sodium borohydride. This compound was employed in initiating the ring-opening polymerization of ε-caprolactone. The resulting polymers were characterized using Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC). The characterization data indicated the star-shaped PCL with phosphazene core were successfully synthesized with narrow molecular weight distribution and high yields. ¹H-NMR analysis was used to calculate the number-average molecular weight. The calculated result from NMR was closer to the theoretical data than that from GPC analysis. Polarizing optical microscopy (POM) combined with differential scanning calorimetry (DSC) was used to study the crystallization behavior of the star-shaped PCL. The result indicated that the highly branched architecture of star-shaped PCL resulted in interrupted crystallization form and subsequently lower melting temperature. Thermogravimetric analysis (TGA) carried out on the star-shaped PCL suggested that introduction of phosphazene rings strengthen the thermal stability of the resulting polymers.     

溴化苄基取代吡啶类季铵盐的制备和抗菌性能

抗菌材料和抗菌制品的研究与应用一直是世界各国研究的重要课题~([1-3]),其中有机抗菌剂占据主要地位.季铵盐是研究比较多的一类有机抗菌剂,它们表现出良好的物理性质,如胶束浓度低,黏弹性好和溶解性强~([4]),同时此类抗菌剂具有强效的抗菌作用~([5]),引起了人们的极大兴趣.季铵盐广泛应用于医药、卫生、食品、饲料工业、农业、纺织、塑料、橡胶、造纸、水处理、油田开采、涂料、日常生活等多种领域~([6-10]).     

Synthesis and characterization of benzothiazolyl substituted anils

The original article to which this Erratum refers was published in Magnetic Resonance in Chemistry 2010, 48: 210–218     

Synthesis and characterization of asymmetric substituted dicarbamates

Several new asymmetric substituted dicarbamates were synthesized with a convenient route.Firstly,tolylene-2,4-diisocyanate dimmer was obtained from monomer with tributylphosphine as catalyst.Then,the dimmer reacted with alcohol(R~1OH) to prepare carbamate substituted uretidione.Finally,uretidione ring was opened and the released isocyanate reacted with another alcohol (R~2OH,R~1≠R~2).     

Synthesis and characterization of tetraoctyloxy substituted naphthalenophanedienes

Tetraoctyloxy-substituted naphthalenophanedienes were synthesized from tetraoctyloxy-substituted dithia[3.3]naphthalenophanes via sequential benzyne Stevens rearrangement, oxidation, and pyrolysis reactions. Surprisingly, only the pseudo-geminal isomer of tetraoctyloxy-substituted dithia[3.3]naphthalenophane was obtained after cyclization of the corresponding starting materials. The structures of the pseudo-geminal isomers of tetraoctyloxy-substituted dithia[3.3]naphthalenophane and tetraoctyloxy-substituted naphthalenophanediene were fully determined by nuclear magnetic resonance spectroscopy, high resolution mass spectrometry, and X-ray crystallography. The pseudo-geminal and pseudo-meta diastereomers of tetraoctyloxy-substituted naphthalenophanedienes were isolated by multiple fractional recrystallization from hexane at 5 °C. The solid state structure of the pseudo-geminal isomer of tetraoctyloxy-substituted naphthalenophanediene revealed strongly distorted naphthyl rings with high levels of ring strain.     

Synthesis and antimicrobial activity of some novel furyl and benzimidazole substituted benzyl ethers

In this study, a series of novel furyl and benzimidazole substituted benzyl ethers were synthesized and evaluated for antibacterial and antifungal activities against S. aureus, Methicillin resistant S. aureus (MRSA), E. coli, C. albicans and C. krusei. Compound 6f and 6h exhibited the most potent anti‐bacterial activity with lowest MIC values of 3.12 μg/mL against S aureus and MRSA, respectively.     

Synthesis,characterization, photophysical and electrochemical properties of oxygen bridged twisted heptatomic biphenyl substituted perylene diimides

The perylene diimide derivatives (s-THBPDI and d-THBPDI) bearing oxygen bridged twisty heptatomic biphenyl in the bay positions of the perylene core through acetylene bond were designed and synthesized. The photophysical properties of the functionalized dyes were investigated in solution and solid state by UV-vis and photoluminescence (PL) spectra. Their UV-vis and PL spectrum both exhibited the different concentration-dependent behaviors due to the difference of chemical structure. Moreover, cyclic voltammetry results indicated that the introduction of oxygen bridged twisted heptatomic biphenyl could decrease the LUMO energy level of the perylene diimide effectively and made it promising material in photoelectric devices.     

Synthesis, characterization, thermal properties and flame retardancy of a novel nonflammable phosphazene-based epoxy resin

Hexakis(4-hydroxyphenoxy)-cyclotriphosphazene (PN-OH) was synthesized through nucleophilic substitution of the chloride atoms of hexachlorocyclotriphosphazene and reduction of the aldehyde groups, and its chemical structure was characterized by elemental analysis, ¹H and ³¹P NMR, and Fourier transform infrared (FTIR) spectroscopy. A new phosphazene-based epoxy resin (PN-EP) was successfully synthesized through the reaction between diglycidyl ether of bisphenol-A (DGEBA) and PN-OH, and its chemical structure was confirmed by FTIR and gel permeation chromatography. Four PN-EP thermosets were obtained by curing with 4,4′-diaminodiphenylmethane (DDM), dicyandiamide (DICY), novolak and pyromellitic dianhydride (PMDA). The reactivity of PN-EP with the four curing agents presents an increase in the order of DDM, PMDA, novolak and DICY. An investigation on their thermal properties shows that the PN-EP thermosets achieve higher glass-transition and decomposition temperatures in comparison with the corresponding DGEBA ones while their char yields increase significantly. The PN-EP thermosets also exhibit excellent flame retardancy. The thermosets with novolak, DICY and PMDA achieve the LOI values above 30 and flammability rating of UL94 V-0, whereas the one with DDM reaches the V-1 rating. The nonflammable halogen-free epoxy resin synthesized in this study has potential applications in electric and electronic fields in consideration of the environment and human health.     

Synthesis of some substituted benzimidazoles with potential antimicrobial activity

Summary The synthesis andin vitro antimicrobial evaluation of several benzimidazole derivatives with different heterocyclic nuclei at position-2 are described.

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Synthese einiger substituierter Benzimidazole mit potentieller antimikrobieller Aktivität

Zusammenfassung Die Synthese und antimikrobielle Prüfung einiger Benzimidazole mit verschiedenen heterozyklischen Substituenten in 2-Stellung wird beschrieben.