Novel N‐Alkylbenzimidazole‐Ruthenium (II) complexes: Synthesis and catalytic activity of N‐alkylating reaction under solvent‐free medium

In this article, direct N‐alkylation reactions of amines with alcohols derivatives have been investigated. For this purpose, a new series ruthenium (II) complexes bearing N‐coordinated benzimidazole complexes with have been synthesized and fully characterized by elemental analysis, FT‐IR, ¹H NMR and, ¹³C NMR spectroscopies. Additionally, the structures of the complexes 2b and 2c have been confirmed by X‐ray crystallography. Although the N‐alkylating reaction is usually performed in toluene, the catalytic study of complexes 2a‐d has carried out no additional solvent and alcohol acted both as solvent and reactant of alkylating by using a little excess of alcohols. Surprisingly, conversion and selectivity of amine product for alkylation reaction have been seen high in medium solvent‐free relative to in toluene.     

Synthesis,spectral, X-ray diffraction and DFT studies on 1-(2-methyl-2-propenyl)-3-(2,3,4,5,6-pentamethylbenzyl)benzimidazolium chloride hydrate

A new benzimidazole based N-heterocyclic carbene (NHC) salt (1) was synthesized by the reaction of benzimidazole precursor with alkyl halide. The structure of 1 was determined by elemental analysis, FT-IR, ¹H NMR and ¹³C NMR spectroscopy tecniques and X-ray crystallography. The compound crystallized in the triclinic space group P-1 with two molecules in the unit cell. The optimization of 1 was firstly performed at B3LYP/6-311G++(d,p) level, then the theoretical spectral studies performed and compared with the experimental values. Besides the frontier molecular orbital energies and chemical reactivity analysis of 1, together with the electrostatic potential and molecular electrostatic potential analyses were performed at the same level of theory.     

New 3-vinylation products of indole and investigation of its Diels-Alder reactivity: synthesis of unusual Morita-Baylis-Hillman-type products

3-Vinylindoles as precursors of carbazole and bis-indole derivatives were synthesized. Then, to form new carbazoles, Diels-Alder reactivity of these vinylindoles was studied with various dienophiles. During the cycloaddition reaction, unusual Morita-Baylis-Hillman-type products were observed. The structure and the formation mechanism of the products is discussed.     

Electricity production by a microbial fuel cell fueled by brewery wastewater and the factors in its membrane deterioration

Electricity production from brewery wastewater using dual-chamber microbial fuel cells (MFCs) with a tin-coated copper mesh in the anode was investigated by changing the hydraulic retention time (HRT). The MFCs were fed with wastewater samples from the inlet (inflow, MFC-1) and outlet (outflow, MFC-2) of an anaerobic digester of a brewery wastewater treatment plant. Both chemical oxygen demand removal and current density were improved by decreasing HRT. The best MFC performance was with an HRT of 0.5 d. The maximum power densities of 8.001 and 1.843 μW/cm2 were obtained from reactors MFC-1 and MFC-2, respectively. Microbial diversity at different condi-tions was studied using PCR-DGGE profiling of 16S rRNA fragments of the microorganisms from the biofilm on the anode electrode. The MFC reactor had mainlyGeobacter,Shewanella, andClostridium species, and some bacteria were easily washed out at lower HRTs. The fouling characteristics of the MFC Nafion membrane and the resulting degradation of MFC performance were examined. The ion exchange capacity, conductivity, and diffusivity of the membrane decreased significantly after foul-ing. The morphology of the Nafion membrane and MFC degradation were studied using scanning electron microscopy and attenuated total reflection-Fourier transform infrared spectroscopy.     

Synthesis and Characterization of Novel Aryl Cyclitols: Polycyclitols

New polycyclitols were synthesized starting from 1,4-naphthoquinone. An endo-selective Diels–Alder cycloaddition between 1,4-naphthoquinone and 1-acetoxybutadiene afforded a diketone. Reduction of the diketone with a NaBH₄-CeCl₃ · 7H₂O system gave a new cyclitol analog diol acetate. Acetylation of this compound afforded a triacetate. Oxidation of the double bond of the triacetate compound with OsO₄ followed by acetylation of hydroxyl groups gave the pentaacetate, whose structure was established unequivocally via application of x-ray crystallographic methods. Hydrolysis of ester groups of pentaacetate under basic condutions furnished the desired and another novel aryl cyclitol.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.]     

Synthesis of Novel Thioethers and Sulfoxide Compounds

Abstract

Thiosubstituted butadiene and butenyne compounds were synthesized from the reactions of 1,1,3,3,4,4-hexachloro-1-butene or 1,1,2,4,4-pentachlorobuta-1,3-diene with different thiols in EtOH/H₂O solution of NaOH. Tris(thio)substituted butadiene compound was treated with potassium tert-butoxide to obtain tris(thio)substituted butatrienyl halide compound. The novel sulfoxide compounds were synthesized from the reactions of polyhalobutadiene compounds with aliphatic thiols in CHCl₃ with m-CPBA at 0°C. The structures of the novel compounds were characterized by micro analysis, FT-IR, ¹H-NMR, ¹³C-NMR, and MS.     

Asymptotics of eigenvalues for regular Sturm-Liouville problems with eigenvalue parameter in the boundary condition

In this paper we obtain asymptotic estimates of eigenvalues for regular Sturm-Liouville problems having the eigenparameter in the boundary condition. The method is based on an iterative procedure solving the associated Riccati equation and producing an asymptotic expansion of the solution in the higher powers of 1/λ1/2 as λ→∞.     

Transfer Hydrogenation of Ketones Catalyzed by 1-Alkylbenzimidazole Ruthenium(II) Complexes

Six [RuCl₂(1-alkylbenzimidazole)(p-cymene)] complexes have been prepared and the new compounds characterized by C, H, N analyses, ¹H NMR, and ¹³C NMR. The reduction of ketones to alcohols via transfer hydrogenation was achieved with catalytic amounts of the complexes in the presence of t-BuOK.     

Effect of Lactoferrin on Odontogenic Differentiation of Stem Cells Derived from Human 3rd Molar Tooth Germ

Stem cell technology has been a great hope for the treatment of many common tissue regeneration-related diseases. Therefore, the main challenge in hard tissue engineering is to make a successful combination of stem cells and efficient inductors such as biomaterials or growth factors, in the concept of stem cell conversion into odontogenic cell. Even though lactoferrin has been reported to promote bone growth in vivo, the molecular mechanism of teeth formation has not been elucidated yet. Different concentrations of lactoferrin were prepared for the analysis of cell toxicity and differentiation evaluations. The odontogenic differentiation of human tooth germ stem cells (hTGSCs) was assessed by gene expression analysis, determination of protein levels in odontogenic differentiation-related protein, measuring alkaline phosphatase (ALP) activity, mineralization, and calcium deposit levels. Lactoferrin-treated group showed the highest ALP activity as opposed to the other groups which were untreated. In addition, the gene expression levels as well as the protein levels of odontogenic factors were found to be high in compared to the control groups. In the current study, it is shown for the first time that there is a significant increase in odontogenic differentiation capacity in hTGSCs when lactoferrin is applied in vitro. The study offers a considerable promise for the development of pulp regeneration by using stem cell technology combined with lactoferrin in functional tooth tissue engineering.     

Stereospecific synthesis of highly substituted novel carbasugar as carbonic anhydrase inhibitors: decahydronaphthalene-1,2,3,4,5,6,7-heptol

Decahydronaphthalene-1,2,3,4,5,6,7-heptol, a new polycyclitol, was synthesized starting from p-benzoquinone. An endo selective Diels-Alder cycloaddition between p-benzoquinone and 1-acetoxybutadiene followed by stereoselective reduction with NaBH₄/CeCl₃·7H₂O led to the formation of an allylic cis-diol. The formed diol was converted into its acetate with Ac₂O/pyridine, in a transformation that required inert atmosphere conditions to suppress a competing aromatization. Controlled oxidation by OsO₄ of two olefinic bonds followed by acetylation yielded the heptaacetate whose structure was established unequivocally via application of X-ray crystallographic methods. Removal of the acetate groups by NH₃ provided the target heptol. In addition, the carbonic anhydrase inhibitory potency of the title compound was investigated and it was shown to be a potent inhibitor compared to the standard CA inhibitors.