A New Taraxastane‐Type Triterpene from Vitex trifolia var. simplicifolia

3‐Oxotaraxer‐14‐en‐30‐al ( 1 ), a new taraxastane‐type triterpene, together with 14 known compounds, taraxerone ( 2 ), 3‐epiursolic acid ( 3 ), 2α,3β‐dihydroxyurs‐12‐en‐28‐oic acid ( 4 ), lupeol ( 5 ), betulinic acid ( 6 ), casticin ( 7 ), artemetin ( 8 ), luteolin ( 9 ), 4‐hydroxybenzoic acid ( 10 ), docosanoic acid ( 11 ), tetracosanoic acid ( 12 ), cerotic acid ( 13 ), β‐sitosterol ( 14 ), and β‐daucosterol ( 15 ), was isolated from the leaves and twigs of Vitex trifolia var. simplicifolia . Compounds 2 – 6 were found for the first time in this plant. Their structures were established by spectroscopic analysis, including 2D‐NMR techniques. Cytotoxic activities of compounds 3 , and 5 – 10 were tested on the three cancer cell lines, PANC‐1, K562, and BxPC‐3. Results revealed that 7 exhibited cytotoxicity against PANC‐1, K562, and BxPC‐3, with IC₅₀ values of 4.67, 0.72, and 4.01 μg/ml, respectively, whereas 8 was inactive against these cancer cell lines. The structure? activity relationship of compound 7 and 8 indicated that the 3′‐OH group in polymethoxyflavonoids is essential for antitumor activity.     

Effect of metal cations [Li+, Na+, K+, Be2+, Mg2+, and Ca2+] on the structure of 2‐(3′‐hydroxy‐2′‐pyridyl)benzoxazole: A theoretical investigation

Density functional theory calculations were performed at the B3LYP/6‐311++G(d,p) level to systematically explore the geometrical multiplicity and binding strength for the complexes formed by alkaline and alkaline earth metal cations, viz. Li⁺, Na⁺, K⁺, Be²⁺, Mg²⁺, and Ca²⁺ (Mⁿ⁺, hereinafter), with 2‐(3′‐hydroxy‐2′‐pyridyl)benzoxazole. A total of 60 initial structures were designed and optimized, of which 51 optimized structures were found, which could be divided into two different types: monodentate complexes and bidentate complexes. In the cation‐heteroatom complex, bidentate binding is generally stronger than monodentate binding, and of which the bidentate binding with five‐membered ring structure has the strongest interaction. Energy decomposition revealed that the total binding energies mainly come from electrostatic interaction for alkaline metal ion complexes and orbital interaction energy for alkaline earth metal ion complex. In addition, the electron localization function analysis show that only the Be? O and Be? N bond are covalent character, and others are ionic character. © 2012 Wiley Periodicals, Inc.     

Investigation on the dissolution of Mn ions from LiMn2O4 cathode in the application of lithium ion batteries: First principle molecular orbital method

The dissolution phenomenon of Mn ions in LiMn₂O₄ (LMO) cathode material for lithium ion batteries (LIBs) was investigated by a first principle calculation using the discrete variational Xα molecular orbital method. It was found that the oxidation number of Mn ions easily increases at high temperatures due to the empty levels of Mn 3d orbitals located in the vicinity of the Fermi energy level of LMO crystal. The changes of density of states (DOS) and Mn‐O bonding properties with doping were examined. Analysis of DOS showed that the substitution of elements with a smaller oxidation number than Mn was found effective in keeping Mn ions at higher oxidation states. From the calculation of bonding properties, the dissolution of Mn was found to be strongly correlated with the covalent nature of Mn‐O bond. Based on the results, we concluded that increasing the covalent character of Mn‐O bond is effective to minimize the dissolution of Mn ions, along with suppressing the formation of Jahn‐Teller‐active Mn³⁺ by inducing Mn ions at high oxidation state with proper selection of doping elements. © 2012 Wiley Periodicals, Inc.     

Ab initio study of the π–π interactions between CO2 and benzene,pyridine, and pyrrole

The π–π interactions between CO₂ and three aromatic molecules, namely benzene (C₆H₆), pyridine (C₅H₅N), and pyrrole (C₄H₅N), which represent common functional groups in metal‐organic/zeoliticimidazolate framework materials, were characterized using high‐level ab initio methods. The coupled‐cluster with single and double excitations and perturbative treatment of triple excitations (CCSD(T)) method with a complete basis set (CBS) was used to calibrate Hartree–Fock, density functional theory, and second‐order M?ller–Plesset (MP2) with resolution of the identity approximation calculations. Results at the MP2/def2‐QZVPP level showed the smallest deviations (only about 1 kJ/mol) compared with those at the CCSD(T)/CBS level of theory. The strength of π–π binding energies (BEs) followed the order C₄H₅N > C₆H₆ ～ C₅H₅N and was roughly correlated with the aromaticity and the charge transfer between CO₂ and aromatic molecule in clusters. Compared with hydrogen‐bond or electron donor–acceptor interactions observed during BE calculations at the MP2/def2‐QZVPP level of theory, π–π interactions significantly contribute to the total interactions between CO₂ and aromatic molecules. © 2013 Wiley Periodicals, Inc.     

Selective Bromination of Dehydroacetic Acid with N-Bromosuccinimide

Bromination of dehydroacetic acid has been carried out with N-bromosuccinimide under various conditions. The reactions led to selective bromination, thereby offering efficient synthesis of 3β-bromodehydroacetic acid (3), 3β,5-dibromodehydroacetic acid (4), 3β,3β-dibromodehydroacetic acid (5), and 3β,3β,5-tribromodehydroacetic acid (6).     

Novel Carbon–Carbon Bond Formation between N‐Methyl‐3‐phenyl‐3‐hydroxypropylamine and Cresols Catalyzed by p‐Toluenesulphonic Acid

The p‐toluenesulphonic acid–catalyzed reaction between appropriate cresols and N‐methyl‐3‐phenyl‐3‐hydroxypropylamine in refluxing toluene resulted in the formation of o‐substituted phenol derivatives by an aromatic nucleophilic substitution reaction.     

A Convenient Method for the Phosphorylation of Phenols with Diethyl Cyanophosphonate

Phosphorylation of phenols with diethyl cyanophosphonate in methylene chloride solution at 0°C is an easy, rapid and good yielding reaction.     

Catalytic Oxidative Cyclocondensation of o‐Aminophenols to 2‐Amino‐3H‐phenoxazin‐3‐ones

The catalytic oxidative cyclocondensation of the o‐aminophenols 1a–f was investigated. The oxidants used were air/laccase, H₂O₂/horseradish peroxidase, H₂O₂/ebselen (3), and TBHP/diphenyl diselenide 4. The products obtained were 2‐amino‐3H‐phenoxazin‐3‐one—questiomycin A, its derivative 2b, and cinnabarinic acid and actinocin (2c,d). Substrates with methyl groups at 4 and 5 positions of benzene ring were converted to different dihydrophenoxazinones 2g,h. Compounds having chlorine atoms at the same positions underwent oxidation to planar phenoxa-zinones 2e,f with elimination of one hydrochloride molecule.     

Cerium(III)-Catalyzed Synthesis of Schiff Bases: A Green Approach

The reaction of primary aromatic amines with aryl aldehydes is found to be catalyzed by cerium chloride heptahydrate under solvent-free conditions to give the corresponding Schiff bases in good yields.     

Synthesis and Luminescence of 14-Aryl- or Alkyl-14H-dibenzo[a,j]xanthenes Catalyzed by 2-1′-Methylimidazolium-3-yl-1-ethyl Sulfate

A facile and efficient synthesis of 14-aryl or alkyl-14H-dibenzo[a,j]xanthenes has been accomplished by treatment of β-naphthol with aryl or alkyl aldehydes catalyzed by 2-1′-methylimidazolium-3-yl-1-ethyl sulfate in ionic liquid [BMIM][BF₄] at 80°C. The luminescence of products was studied in detail.