bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamics of Atomic and Molecular Hydrogen Elimination from Hydrocarbons at VUV Excitation
Authors: Lin Jim J. , Harich Steve , Hwang Dennis W. , Wu Malcom S. , Lee Yuan T. , Yang Xueming
Published: May 2015

Elimination of atomic hydrogen (H) and molecular hydrogen (H2) are important elementary chemical processes in photochemistry and combustion chemistry. Recently, unique and sensitive detection techniques for atomic and molecular hydrogen detection were developed in our laboratory. Using the advanced molecular beam methods, we have studied the photodissociation of a few typical hydrocarbons at 157 nm excitation, especially their atomic and molecular hydrogen elimination processes. In this report, we will briefly describe the results from photodissociation of propane, ethylene, propyne and methanol at 157 nm excitation. These molecules represent different classes of hydrocarbons such as alkane, alkene, alkyne and alcohol. Through careful studies on differently deuterated compounds, clear pictures of selective atomic and molecular hydrogen elimination processes can be constructed for all of the above compounds. These results will help us to understand the dissociation dynamics of the small hydrocarbon molecules.
Structural and Electron Density Studies on a Chromium(IV)‐Oxo Complex [CrIV(O)(TMP)]
Authors: Lin Hsiu‐Mei , Sheu Hwo‐Shuenn , Wang Chih‐Chieh , Che Chi‐Ming , Wang Yu
Published: May 2015

The electron density distribution of a chromium(IV)‐oxo complex, [CrIV(O)(TMP)] (TMP = 5,10,15,20‐tetrakis‐p‐methoxyphenyl porphyrin), is investigated by molecular orbital calculation. The molecular and crystal structure of the compound is studied by x‐ray diffraction. It belongs to the space group 1 2, Z = 2, a = 14.979(4) Å, b = 9.752(3), c = 15.605(3) Å, β = 100.97(2)°, V = 2238(1) Å3, Mo Kα radiation λ = 0.7107 Å, R = 4.9%, Rw = 3.5% for 3575 observed reflections. Cr is five‐coordinated in a square pyramidal fashion with the Cr atom located 0.42 Å toward the oxo‐ligand. Deformation density maps are derived from the single point molecular orbital calculation on the basis of HF and DFT(density functional theory) calculations. The accumulation of deformation density along the C‐H, C‐C, C‐N and C‐O bonds in the porphyrin ligand is well represented. The asphericity in electron density around the Cr ion is clearly demonstrated. Natural bond orbital analysis (NBO) reveals that the Cr‐Ooxo is actually a triple‐bond character (σ2π4) and the four N of pyrrole serves as a σ‐donor to Cr. The Cr‐Npyrrole bond is essentially a dative bond d‐Orbital populations of Cr derived from both calculations are in good agreement with each other. Planar dπ‐orbital is the most populated, which is in accord with the prediction from crystal field theory. Detail bond characterization of the Cr‐L, multiple bond is discussed.
The Synthesis and Application of the Mesoporous Molecular Sieves MCM‐41 — A Review
Authors: Lin Hong‐Ping , Cheng Yah‐Ru , Lin Chung‐Rong , Li Feng‐Yin , Chen Chang‐Lin , Wong She‐Tin , Cheng Soofin , Liu Shang‐Bin , Wan Ben‐Zu , Mou Chung‐Yuan , Tang Chin‐Yuan , Lin Ching‐Yen
Published: May 2015

We report a “delayed neutralization” process for the preparation of highly‐ordered aluminosilicate MCM‐41 molecular sieves with high thermal and hydrothermal stability, and sharp pore size distribution. However, the structural order and pore size are dependent on the carbon chain length. In the mixture surfactant systems, the pore size of the MCM‐41 materials could be fine‐tuned. The pore size can be extended from 2.5 to 4.5 nm by adding a suitable amount of hydrocarbons. The tubular morphology of the MCM‐41 material of 0.3 to 10 micrometers diameter, where the wall consists of coaxial cylindrical pores of nanometers MCM‐41, can be obtained by careful control of the surfactant‐water content and the rate of condensation of silica. An optimum condition for automatic synthesis of the hierarchical TWT structure has been accomplished. The addition of 1‐alkanols as cosurfactant would not only improve the order of the MCM‐41 hexagonal structure but also promote the formation of micrometer‐sized hierarchical materials, for example: tubules‐within‐tubule and uniform‐sized hollow spheres of diameter 5.0 ± 1.0 μm. However, the inside of the micron spheres has intricate structures possessing various topological genus ranks. The MCM‐41 is a good supporter for Molybdenum oxide catalysts. The rate of deactivation in the catalytic reaction of ethyl‐benzene dehydrogenation to styrene increases in the order: MT< MP< SiO2. The physically mixed samples have higher catalytic activity than impregnated ones.
Palladium(II) Complexes of N‐(2‐Thienylmethylidene)aniline Derivatives
Authors: Hwang Wen‐Shu , Lai Jiun‐Hwa , Wang Dong‐Liang , Chiang Michael Y.
Published: May 2015

Coordination reactions of N‐(2‐thienylmethylidene)aniline derivatives, L, with PdCl2 or [PdCl4]2− in ethanol yield stable complexes of the type trans‐(L)2PdCl2 with the azomethine nitrogen atoms as σ donors. These are not readily convertible to othor‐palladated complexes. An X‐ray crystallographic study of the complex (L2)2PdCl2 reveals a centrosymmetric geometry. The structure is in the triclinic space group \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm P}\bar 1 $\end{document} with a = 8.633(2) Å, b = 12.759(3) Å, c = 8.398(2) Å, α = 96.65(5)°, β = 111.47(5)*, γ= 101.28(6)°, and Z = 1. The final R factor is 0.043 (Rw = 0.044) for 2396 observed reflections. There is no real bonding between a thiophene sulfur atom and a central palladium ion. However, a long distance interaction between S and Pd does exist.
Synthesis, Characterizations, and Structure of Group 4 Metallocene Complexes of Some Difunctional Ligands Containing Oxygen and Sulfur Donors
Authors: Lin Show‐Jinn , Ho Yuh‐Cho , Gau Han‐Mou
Published: May 2015

Reactions of CH3OCH2CH2OH, PhOCH2CH2OH, o‐CH3OC6H4CH2OH, or PhSCH2CH2OH with Cp2ZrCl2 in the presence of NEt3 gave series monomeric complexes Cp2ZrClX (X = OCH2CH2OCH3 (1), OCH2CH2OPh (2), o‐OCH2C6H4OCH3 (3) or OCH2CH2SPh (4)). In a reaction of Cp2TiCl2 with PhSCH2CH2OH in the presence of NEt3, the complex Cp2TiCl(OCH2CH2SPh) (5) was obtained. These complexes were characterized by the 1H and 13C NMR, and the chemical shifts of the Cp rings for complexes 1–4 are nearly identical, despite differences in ligands for an indication of similar structures of these complexes around the metal center. Complex 4 crystallizes into the monoclinic P21/c space group with a = 13.806(3) Å, b = 16.394(3) Å, c = 7.838(2) Å, β = 100.85(3)° Z = 4, R = 0.029, Rw = 0.044, and Gof = 1.19. The molecular structure of complex 4 shows that the 2‐(phenylthio)ethoxide bonds to the Zr metal center through the alkoxide donor leaving the thioether donor free from coordination.
Rate Study of Samarium Diiodide Reduction of Alkyl Halides and 2‐Heptanone
Authors: Lin Tzuen‐Yeuan , Fun Ming‐Ren , Chang Shih‐Chun
Published: May 2015

Rate constants directly measured from GC‐analyzed method for SmI2 reduction of alkyl halides were obtained. The rates increase in the orders of primary, secondary, tertiary RX and RCl < RBr < RI as expected. 2‐Heptanone was chosen as the partner of alkyl halide in the samarium Barbier reaction. In the absence of HMPA, the reaction orders of alkyl halide and ketone were determined as first and zero order, respectively.
A Convenient Synthetic Approach to Newly Condensed Pyrazoloazines Based on Pyrazolo[3,4‐b]pyridine
Authors: El‐Emary Talaat I.
Published: May 2015

The reaction of 6‐amino‐5‐cyano‐3‐methyl‐1H‐1‐phenylpyrazolo[3,4‐b]pyridine (2) and 6,7‐dihydro‐3‐methyl‐6‐oxo‐1H‐1‐phenylpyrazolo[3,4‐b)]pyridine‐5‐carbonitrile (3) and 5‐amino‐3‐methyl‐1‐phenyl‐1H‐pyrazolo[3,4‐b]‐1H‐pyrazolo[4′,3′‐e]pyridine (12) with different reagents have been conducted to give newly condensed pyrazoloazines.
Synthesis of Acetal Dioxa‐Cage Compounds Via Intramolecular Acetalization
Authors: Chang Meng‐Yang , Lin Ching‐Han , Chang Nein‐Chen
Published: May 2015

An approach to tricyclic acetal dioxa‐cage structure (1) and (2) involving intramolecular acetalization as the key protocol is reported.
Skeletal Reorganization of Mercaptoacetaldehyde Dialkyl Acetal in Acid: Formation of Disulphide, 1,2‐Bis(mercapto)ethylene and 1,1,2‐Tris(mercapto)ethane Derivatives
Authors: Ong Chi Wi , Yen Sin Fei , Chou Yi Meen
Published: May 2015

The reaction of mercaptoacetaldehyde dialkyl acetals 1a‐c in the presence of sulfuric acid, polyphosphoric acid and zinc chloride is described. Other than the disulfide reported previously, new compounds 1,2‐bis‐(mercapto)ethylene, 1,2,3‐tris‐(mercapto)ethane and 1,2‐bis‐(mercapto)methane have been isolated for the first time.
Desilylative Oxidation of Alkyl Trimethylsilyl Ethers with Pyridinium Fluorochromate
Authors: Ho Tse‐Lok , Jana Gour Hari
Published: May 2015

Direct conversion of alkyl trimethylsilyl ethers to carbonyl compounds is accomplished using PFC in dichloromethane at room temperature. For a similar oxidation of t‐butyldimethylsilyl ethers the PCC‐n‐Bu4NF combination may be employed.
Synthesis of Biologically Active Glycopeptides
Authors: Koeller Kathryn M. , Wong Chi‐Huey
Published: May 2015

Protein glycosylation is an important post‐translational event; however, the role carbohydrates play in glycoprotein structure and function is poorly understood, mainly due to the difficulty associated with the synthesis of this class of molecules. This review describes the types and functions of glycopeptides found in nature and the synthesis of biologically active glycopeptides, including vaccines, antibiotics, ligands of receptors involved in signaling, and various structural motifs found in glycoproteins. The synthetic strategies described in this review cover both chemical and enzymatic methods. In addition, structural studies of synthetic glycopeptides and their mimetics, and chemoenzymatic synthesis of complex glycoproteins with well‐defined carbohydrate structure for the study of the effect of glycosylation on protein structure and function are also discussed.
The Synthesis of N4‐(6‐Aminopyridin‐2‐yl)‐2′‐deoxycytidine for Recognizing the CG Base Pair at Neutral pH by Oligodeoxyribonucleotide‐Directed Triple Helix Formation
Authors: Chin T.‐M. , Chung K.‐Y. , Chen J.‐J. , Lin W.‐C. , Kan L.‐S.
Published: May 2015

The sequence‐specific recognition of double‐helical DNA by oligodeoxyribonucleotide‐directed triple helix (triplex) formation is limited mostly to purine tracts. To interrupt the purine tract in a target sequence, a non‐natural deoxyribonucleoside N4‐(6‐aminopyridin‐2‐yl)‐2′‐deoxycytidine (pC) was designed to interact with the C base in the CG base pair. The protected phosphoramidite synthon of pC was synthesized in seven steps and then was incorporated into an oligodeoxyribonucleotide by an automatic DNA synthesizer. Two 22‐mers, designated as C2 and P, with a common sequence of 5′‐d‐TmCTXTmCTTCTGTCTCCAGACAG were synthesized in this study. mC is 5‐methyl‐2′‐deoxycytidine and X is either 2′‐deoxycytidine (C) or pC for C2 and P, respectively. C2 is able to form a paper clip type triplex with one C · CG mismatched base triad in slightly acidic conditions but not at the neutral pH. On the other hand, P forms a stable triplex under both acidic and neutral conditions. This indicates that pC is able to form a pC · CG base triad in the triplex. Their physical properties were studied by UV thermal melting experiments and circular dichorism spectroscopy (CD). The thermal melting results imply that the pC · CG base triad is as stable as the C+ · GC triad at pH 6.0, and pC helps the triplex formation preferably at neutral to acidic pH. In addition to the hydrogen bonding interaction with the CG base pair, the hydrophobic interaction of pC may also play an important role in stabilizing the triplex formation of oligodeoxyribonucleotides. In the presence of spermine at either pH 5.0 or pH 6.0, the melting temperature of the third strand of P was elevated about 30 and 21 °C, respectively. Thus, spermine can enhance the stability of the triple‐helical structure.
25Mg NMR Relaxation Study of Mg2+‐ATP Complexation in Solutions
Authors: Shien Zhi‐Shian , Luo Tzy‐Jiun , Hwang Lian‐Pin
Published: May 2015

25Mg NMR relaxation has been applied to characterize the kinetic and dynamic parameters in the complexation process of the Mg2+ ion with adenosine triphosphate. A modified linear prediction with singular value decomposition method developed earlier is used to obtain the preliminary chemical shift separation between the free 25Mg2+ ion and the 25Mg2+‐ATP complex. Then the 25Mg2+ NMR null point spectra is invoked to find the chemical shift separation and the quadrupolar coupling constant of the complex. With the knowledge of those parameters, T1 and line width data at 30.62 MHz and 18.37 MHz can be analyzed to determine the correlation times for the fluctuation of electric field gradient at 25Mg and the dissociation rate constants of the complex at the temperature range of 270–320 K. An activation energy of 8.8 kcal/mol for dissociation rate constant is obtained. It is also found that the reorientational motion of the 25Mg2+‐ATP complex is not significantly affected by the formation of ATP aggregates. A similar conclusion is further obtained by comparing the T1 data of β‐31P in ATP and Mg2+‐ATP solutions.
Sequence Analyses in PDPS/PDMS Statistical Random Copolymers
Authors: Yang Mei‐Hui , Hwang Yeun‐Hsing , Liu Jiann‐Chang
Published: May 2015

The anionic copolymerization of hexaphenylcyclotrisiloxane (P3) and hexamethylcyclotrisiloxane (D3) under non‐equilibrium conditions was carried out for synthesizing a series of poly(diphenylsiloxane‐stat‐dimethylsiloxane) copolymers. The sequence analyses of these copolymers were studied. Sequence distribution up to the pentad level is observable in the 1H NMR spectrum. The sequence distributions calculated from a pentad model by using Bovey's method, interpret the 1H NMR spectra (SiCH3 only) of all the copolymers very well. However, the triad model was only valid for relatively lower P3 content (< 50 mol%) copolymers.
Preparation of Chiral Phosphorus(V) Reagents and Their Uses with Borane in the Enantioselective Reduction of Ketones
Authors: Chen Guo‐Hsian , Hsu Jue‐Liang , Yang Wen‐Bin , Fang Jim‐Min , Lee Gene‐Hsiang , Liu Yi‐Hung , Wang Yu
Published: May 2015

Chiral pentavalent phosphorus reagents 5–17 were prepared from POCl3 and ephedrine (or the related α‐amino alcohols), followed by substitution with nucleophiles of phenylmagnesium bromide, alcohols, amines, diamines and triamines. The substitution reactions occurred in a stereospecific manner with retention of the configuration at the phosphorus center. The structures of these phosphorus(V) reagents were determined by spectral methods and verified by X‐ray diffraction in several instances. These phosphorus(V) reagents were used with borane/dimethylsulfide complex in the enantioselective reduction of aromatic, aliphatic and heterocyclic ketones. The phosphorus(V) reagents likely functioned as Lewis bases to react with borane, forming in situ zwitterionic species as the chiral reducing agents. The reactions were generally carried out at 0 °C in tetrahydrofuran solution with a molar ratio of ketone/borane/phosphoramidate = 1:1:0.2 to afford secondary alcohols with modest enantioselectivity, up to 67% ee in the reduction of 4′‐methylacetophenone.
Chemical Constituents of the Pericarp of Platycladus orientalis
Authors: Kuo Yueh‐Hsiung , Chen Wen‐Chin
Published: May 2015

In previous papers, we have reported two new compounds, 15‐hydroxypinusolidic acid and platydiol, from the pericarp of Platycladus orientalis. In addition to the above compounds, the isolation and identification of twenty‐one compounds from the same source are described. Their structures were determined on the basis of spectral evidence as well as direct comparison with authentic samples. These compounds included four fatty alcohols and acids, three monolignols, one sesquiterpene, nine diterpenes, two steroids, one flavone, and one sugar. Among these, docosyl 3‐hydroxyferulate is a new compound. And docosyl trans‐ and cis‐ferulates were isolated in pure form.
Organocopper Mediated Conjugate Addition of Vinyl Grignard Reagent to α,β‐Unsaturated Acylsilane
Authors: Tsai Yeun‐Min , Sieh Jiuen‐Ahn
Published: May 2015

Vinyl Grignard reagent added to trans‐cinnamaldehyde in the presence of cuprous iodide to give conjugate addition product in good yield.
A NMR Chemical Shift Analysis on Two Nonconjugated Tri‐π‐Systems
Authors: Chow Tahsin J. , Chu Kuo‐Pin , Liu Shou‐Shun , Liu Ching‐Yang
Published: May 2015

Electronic interactions in two nonconjugated tri‐π systems are analyzed in terms of 13C NMR chemical shifts. Comparisons of chemical shift values (Δδ) among di‐methylenes, di‐ketones and methylene‐ketones support the presence of electron delocalization among the three π moieties.
A Sensitive Measurement of Maleic Hydrazide by a Differential Pulse Voltammetry Followed by a Cleansing Pulse Train
Authors: Lin Meng Shan , Jan Bor Iuan
Published: May 2015

In this current project, we report the most sensitive scheme for the measurement of maleic hydrazide by a modified differential pulse voltammetry (DPV) which is composed of a conventional DPV followed with a cleansing pulse train. The absorbed oxidized species (1,2‐pyridazine‐3,6‐dione) on the solid electrode surface cause subsequent mass transfer hindrance which can be removed easily by a cleansing pulse train of ±0.1 volts, 50 Hz for 5 minutes at the end of each voltammetric run. This scheme possesses the advantage of high sensitivity (submicro‐molar range), which may be used in sensitive maleic hydrazide measurement or toxicity studies.

This scheme offers a better tool to study a very low concentration of maleic hydrazide. A slope of 59.2 mV per decades from the potential versus pH plot was obtained. This result indicates that these are two electrons and two protons oxidation processes. The linear range of the calibration plot is up to 50 μM with a correlation coefficient of 0.9999. The sensitivity of the linear portion of the calibration plot yields a slope of 13.63 nA/μM with a detection limit of 20 nM (S/N = 3). The width of half peak width is 100 mV at the injection of 22 μM maleic hydrazide. Precision study possesses a relative standard deviation of 4.1% (n = 20).
Application of Cryptand/Polystyrene Drift‐Type Phase Transfer Catalysts for Reduction of Ketones
Authors: Li Jane‐Hwa , Shih Jeng‐Shong
Published: May 2015

A drift‐type phase transfer catalyst, cryptand‐22, adsorbed on poly(styrene/diviny benzene)‐sulfonic resin was prepared and applied to catalyze the reduction of ketones, e.g., acetophenone, benzophenone and benzaldehyde with NaBH4 as a reducing agent. Before the reaction, cryptand‐22 was adsorbed on the sulfonic resin with ion‐pairing, resin‐SO3− +NH‐cryptand‐22. The ion‐pairs can be destroyed by adjusting the basicity of the reaction solution with NaOH and the cryptand can be released from the resin into the reaction solution as a homogeneous catalyst during the reaction period. After the reaction, the cryptand catalyst can be readsorbed on the resin by adjusting the acidity of the solution with HCl and can be readily recovered by filtration like a heterogeneous catalyst. The draft‐type cryptand catalyst exhibited better catalytic ability than some common crown ethers, e.g., 15‐crown‐5, benzo‐15‐crown‐5, 12‐crown‐4 and dibenzo‐18‐crown‐6 for the reduction of acetophenone with NaBH4. Effects of solvents, pH of solutions, concentration of the catalyst, reducing agents and resin property on the reduction of ketones were investigated and discussed. The reaction mechanism of the cryptand catalyzed reduction was also studied.
The First Total Synthesis of Preverecynarmin
Authors: Lan Jiong , Liu Zuosheng , Li Yulin , Cen Wen , Xing Yacheng
Published: May 2015

Preverecynarmin, isolated from a pennatulacean coral, has been synthesized from E,E‐farnesol. The key steps are alkylation of the cyanohydrin trimethylsilyl ether 5 with the halide 6, the regioselective epoxidation of the siloxyl ether 9, and the intramolecular macrocyclization of the siloxyl ether 12 induced by Ti(0).
Synthesis of New 2‐[(Substituted‐pyrazol‐1‐yl)carbonyl]‐thieno[2,3b]pyridine Derivatives Using 1,3‐Diketones, Alkylethoxymethylenes and Ketene Dithioacetals
Authors: Ho Yuh‐Wen
Published: May 2015

The reaction of 3‐amino‐4,6‐dimethyl‐2‐thieno[2,3‐b]pyridine carbohydrazide (1) with appropriate 1,3‐diketones 2a‐2d in glacial acetic acid afforded 3‐amino‐2‐[(3,5‐disubstituted‐pyrazo)‐1‐yl)carbonyl]‐4,6‐dimethylthieno[2,3‐b]pyridines 3a‐3d. 3‐Amino‐2‐[(5‐amino‐3,4‐disubstituted‐pyrazol‐1‐yl)carbonyl]‐4,6‐dimethylthieno[2,3‐b]pyridines 5a‐5h were also prepared by treatment of carbohydrazide 1 with appropriate alkylethoxymethylenes and ketene dithioacetals 4a‐4h, respectively.
Oxidative Cleavage of o‐Hydroxyphenyl Phosphate by Iodobenzene Diacetate
Authors: Wu Pei‐Lin , Chen Jhy‐Hong , Huang Ded‐Shih
Published: May 2015

The protecting o‐hydroxyphenyl group in the synthesis of mono‐ or dialkyl phosphates (6 or 8) could be removed by oxidative cleavage of mono‐ or dialkyl o‐hydroxyphenyl phosphates (3 or 7) using iodobenzene diacetate.
Photoredox Properties of Iron(III) Fluoro Complexes Containing Tetradentate Open‐Chain N2O2Ligands
Authors: Šima Jozef , Mrázová Juliana , Kotočová Adela
Published: May 2015

Tetradentate open‐chain Schiff base N2O2‐ligands of acacen, benacen or salen type and fluoride anions F− coordinate to the iron(III) central atom in methanol forming the complexes [Fe(N2O2)(CH3OH)F]. The complexes do not undergo spontaneous redox changes when kept in the dark. Their irradiation into intraligand or ligand‐to‐metal charge transfer bands causes the photoreduction of Fe(III) to Fe(II) associated with oxidation of metanol to its radical CH2OH. The final products of the primary photoredox and secondary dark redox processes, Fe(II) and CH2O, are formed in a 2:1 molar ratio. The efficiency of the axial methanol ligand photooxidation is strongly wavelength dependent and influenced by the peripheral groups R of the tetradentate ligands
Structural Characterization of Metal Ions Incorporated in Molecular Sieve Frameworks
Authors: Wei An‐Chyi , Chao Kuei‐Jung
Published: May 2015

Isomorphous and non‐isomorphous substitutions of transition metal and IIIA elements for framework atoms of molecular sieves are very interesting in order to modify their acidic and redox catalytic properties. In this paper, we review the interaction between metal cations other than Al+3 with zeolitic frameworks in Ti, Co, V and Ga‐containing silicate and aluminophosphate zeolites detected by spectroscopic investigations. During synthesis and redox treatments, solvent, oxidant and surface silanol groups sometimes were found to attach to the framework metal ion sites, perhaps involved in the variation from tetrahedral to non‐tetrahedral coordinations.
Applications of Intramolecular Cyclopropanations of Chiral Secondary Allylic Diazoacetates
Authors: Martin Stephen F. , Hillier Michael C.
Published: May 2015

The diastereomeric secondary allylic diazoacetates 6a,b and 8a,b, which were readily prepared from the common intermediate 4, were cyclized in the presence of the achiral catalyst Cu(TBS)2 to furnish mixtures of the adducts 9a,b/10a,b and 12a,b/13a,b, respectively; in these cyclizations, the diastereoselectivity of the reaction was substrate controlled. When 6a,b and 8a,b were cyclized in the presence of the chiral catalysts Rh2[(5S)‐MEPY]4 or Rh2[(5R)‐MEPY]4, the substrate‐based selectivity could be reversed if the chirality of the substrate and catalyst were matched. The advantages associated with the use of chiral catalysts to effect the diastereoselective cyclization of chiral allylic diazoacetates were demonstrated by the synthesis of 25, which comprises the cyclopropane subunit found in the diterpene ingol B (14).
Homologous SNV Reaction: Synthesis of l‐Methyl‐4‐[4′‐phenylsulfonyl‐1′,3′‐butadienyl]pyridinium Iodide and Its Reactivity with Thiol Groups Giving Rise to the Chromophoric Thioether
Authors: Holler Michel , Burger Alain , Biellmann Jean‐François
Published: May 2015

Thioether 4‐[(1′E,3′E)‐4′‐phenylsulfanyl‐1,3′‐butadienyl]pyridine 8 and sulfone 4‐(4′‐phenylsulfonyl‐1′,3′‐butadienyl)pyridine 14 were prepared by reaction of the carbanions derived from allylic thioether or allylic sulfone with isonicotinaldehyde. The reaction with the sulfonyl carbanion occurred at the α position and on heating the alcolate gave the dienic sulfone 14. The corresponding pyridinium iodide 10 and 15 were prepared by reaction with methyl iodide, respectively, on pyridine derivates 8 and 14. The dienic pyridinium thioether 10 showed a long wavelength absorption band centered at 420 nm. The reaction of dienic pyridinium sulfone 15 with thiophenol gave the dienic pyridinium thioether 10 by a nucleophilic vinylic substitution. The reaction of sulfone 15 with glutathione was of second order and the rate constant was 8.5 M−1s−1 at 30°C and pH 7, about 500 times smaller than the rate constant observed with (E)‐1‐methyl‐4‐(2‐methylsulfonyl‐1‐ethenyl)pyridinium iodide 1. The dienic pyridinium thioether 10 was a negative solvatochrome.
Enantioselective Syntheses of Substituted γ‐Butyrolactones
Authors: Eliel Ernest L. , Bai Xu , Ohwa Masaki
Published: May 2015

The previously described chiral 2‐acyloxathianes 5 (Scheme I) are used in two different enantioselective syntheses of γ‐butyrolactones. In one synthesis, Grignard addition, cleavage and reduction to carbinols RR'C(OH)CH2OH is followed by tosylation, malonate homologation, lactonization, and removal of the carbomethoxy group to give optically active γ‐lactones. A modification of this synthesis (Scheme I) leads to optically active α‐methylene‐γ‐lactones.

In the second synthesis, reaction of a bromomagnesium enolate with ketones 5 leads to β‐hydroxyesters, which, by appropriate sequences of reduction and cleavage (Scheme II) are converted to optically active α‐ or β‐hydroxy‐γ‐lactones.
Solvent and Substituent Effects in the Solvolysis of 9‐Aryl‐9‐bromofluorenes
Authors: Liu Kwang‐Ting , Lin Yen‐Shyi
Published: May 2015

The solvolysis of eight 9‐aryl‐9‐bromofluorenes (6b∼6i) in a variety of solvents were studied. Correlation analysis using single‐parameter Grunwald‐Winstein equation (Eqn. 1) with different Y scales showed good linearity (R ≥ 0.98) for most cases if YxBnBr was employed. Linear relationships were observed from Hammett‐type analysis of logarithm of rate constants using Brown‐Okamoto σ+ constants (Eqn. 3), although inverse order of k(p‐CF3)/k(m‐ CF3) was realized in a number of cases. The ρ values were found to vary slightly with different solvent systems. Calculated atomic charge reveals the similarity between 9‐phenyl‐9‐fluorenyl cation (7) and triphenylmethyl cation (8). An extended charge delocalization throughout the fluorenyl ring led to the conclusion of the insignificance of antiaromaticity, which was in harmony with that obtained in previous studies. The variation of relative kBr/kCl rate ratios was attributed to the electrophilic pull by solvents in solvolysis.
Chelating and Tellurolate Ligand‐Transfer Studies of the Complex fac‐[Fe(CO)3(TePh)3]−: Crystal Structures of Heterodinuclear (CO)3Mn(μ‐TePh)3Fe(CO)3 and CpNi(TePh)(PPh3)
Authors: Hsieh Chien‐Kuo , Lo Feng‐Chun , Lee Gene‐Hsiang , Peng Shie‐Ming , Liaw Wen‐Feng
Published: May 2015

Complex fac‐[Fe(CO)3(TePh)3]− was employed as a “metallo chelating” ligand to synthesize the neutral (CO)3Mn(μ‐TePh)3Fe(CO)3 obtained in a one‐step synthesis by treating fac‐[Fe(CO)3(TePh)3]− with fac‐[Mn‐(CO)3(CH3CN)3]+. It seems reasonable to conclude that the d6 Fe(II) [(CO)3Fe(TePh)3]− fragment is isolobal with the d6 Mn(I) [(CO)3Mn(TePh)3]2− fragment in complex (CO)3Mn(μ‐TePh)3Fe(CO)3. Addition of fac‐[Fe(CO)3(TePh)3]− to the CpNi(I)(PPh3) in THF resulted in formation of the neutral CpNi(TePh)(PPh3) also obtained from reaction of CpNi(I)(PPh3) and [Na][TePh] in MeOH. This investigation shows that fac‐[Fe(CO)3(TePh)3]− serves as a tridentate metallo ligand and tellurolate ligand‐transfer reagent. The study also indicated that the fac‐[Fe(CO)3(SePh)3]− may serve as a better tridentate metallo ligand and chalcogenolate ligand‐transfer reagent than fac‐[Fe(CO)3(TePh)3]− in the syntheses of heterometallic chalcogenolate complexes.
Stoichiometric vs Catalytic MeLi Reaction with the Mixture of (ẽ5‐C5H5)Fe(CO)2l and P(OR)3: Nucleophilic Methylation vs Arbuzov‐Like Dealkylation
Authors: Uche B. Eke , Liao Yi‐Hsien , Wen Yuh‐Sheng , Liu Ling‐Kang
Published: May 2015

The reaction of stoichiometric MeLi with the 1:1 mixture of (ẽ5‐C5H5)Fe(CO)2I/P(OR)3 (R = Me, Et, and Ph) at −78°C changes the bonding mode between metal and ring from (ẽ5‐C5H5) to (ẽ4‐exo‐MeC5H5) and the oxidation state of metal from Fe(II) to Fe(O), the novel complexes (ẽ4‐exo‐MeC5H5)Fe(CO)2P(C)R)3 being obtained in 45‐57% yields. The reaction of trace MeLi with the 1:1 mixture of (ẽ5‐C5H5)Fe(CO)2I/P(OMe)3 at −78°C results in 70% yield of the phosphonate complex (ẽ5‐C5H5)Fe(CO)2P(O)(OMe)2 which is an Arbuzov‐like dealkylation product from the cationic intermediate [(ẽ5‐C5H5)Fe(CO)2P(OMe)3+] and the iodide. The amines could assist the Arbuzov‐like dealkylation of [(ẽ5‐C5H5)Fe(CO)2P(OMe)3+] [PF6−] where iron‐carbamoyl intermediates are likely involved in the case of primary amines.
The Mechanism Study on the Catalytic Synthesis of 2,6‐Dimethylphenol from KA‐Oil and Methanol over Magnesium Oxide Catalysts
Authors: Wang Fey‐Long , Tsai Tan‐Feng
Published: May 2015

Catalytic synthesis of 2,6‐dimethylphenol from KA‐oil (a mixture of cyclohexanol and cyclohexanone) and methanol was achieved by using magnesium oxide‐supported chromium oxide catalysts in one step. At higher conversion (> 90%), dimethylphenol was formed in high yield (>60 %).

The activity of Cr/MgO catalysts depended on the concentration of chromium. The yield of 2,6‐dimethylphenol was also affected by the composition of the ratio of cyclohexanol to cyclohexanone in KA‐oil. Cyclohexanol and cyclohexanone reacting with methanol under the same conditions indicated that pure cyclohexanol or cyclohexanone is less reactive than their mixture, KA‐oil. The adsorption properties of cyclohexanol and cyclohexanone on the surface of Cr/MgO determined by FT‐IR spectroscopy suggest that cyclohexanone is easily reduced to cyclohexanol by the hydrogen which formed in the reaction, and then further reacted with methanol to form 2,6‐dimethyphenol.
Calix[4]arenes with a Lid in their Upper Rims: 1,3‐Dipolar Cycloaddition Reactions of Benzonitrile Oxides with 5‐Allyl‐, 5,11‐Dially‐ and 5,17‐Diallylcalix[4]arenes
Authors: Shu Chun‐Mei , Lin Wei‐Ling , Lee Gene‐Hsiang , Peng Shie‐Ming , Chung Wen‐Sheng
Published: May 2015

The upper rim substituted mono‐ and diisoxazolinomethylcalix[4]arenes 9‐23 are synthesized in good yields from 1,3‐dipolar cycloaddition reactions of papa‐substituted phenyl nitrileoxides with 5‐allyl‐, 5,11‐diallyl‐and 5,17‐diallycalix[4]arenes 5‐7; the structures of 9‐23 are consistent with a ‘cone’ conformation and the ‘vase‐with‐a‐lid’ structure of 11 was confirmed by a single‐crystal x‐ray analysis. Preliminary results show that the monoisoxazolinomethylcalix[4] arene can form an inclusion complex with ammonium cation.
Nonsteroidal Constituents from Solanum Incanum L.
Authors: Lin Yun‐Lian , Wang Wan‐Yi , Kuo Yueh‐Hsiung , Chen Chieh‐Fu
Published: May 2015

Sixteen compounds were isolated from the aerial parts of Solanum incanum L. These compounds included ten flavonoids (1‐10), chlorogenic acid (11), adenosine (12), benzyl‐O‐β‐D‐xylopyranosyl(1→2)‐β‐D‐glucopyranoside (13), and three phenylalkanoic acids (14‐16). The structures were determined from their physical and spectral data. Among these compounds, kaempferol 3‐O‐(6″′‐O‐2,5‐dihydroxycinnamoyl)‐β‐D‐glucopyranosyl (1→2) β‐D‐glucopyranoside (10) was identified as a new compound.
Efficient Synthesis of Alkyl End‐Capped Oligoheterocycles via the Use of Palladacycle Catalyst
Authors: Luo Fen‐Tair , Bajji Ashok C.
Published: May 2015

The preparation of mixed thiophene/furan oligomers with alkyl groups at α,α′‐position by the method which we discovered recently in our lab is presented. Thus, the mixed thiophene/furan oligomers can be prepared in good yields from monoiodoarene in the presence of 5 mol % of palladacycle catalyst and 1.2 equiv of N,N‐diisopropylethylamine in DMF at 100°C for 8 h.
A Facile Synthesis of Azidoformate via Chloroformate
Authors: Wu Pei‐Lin , Su Chia‐Hao , Gu Yi‐Jeng
Published: May 2015

This work synthesized chloroformates by slowly adding alcohols into a suspension of trichloromethyl chloroformate, instead of phosgene, along with activated charcoal in tetrahydrofuran. This chloroformylation yielded chloroformates in near quantitative yield. The subsequent reaction between chloroformates and sodium azide in dry acetone produced azidoformates in a high yield.
Synthesis of 3‐[5‐methyl‐1‐(4‐methylphenyl)‐1,2,3‐triazol‐4‐yl]‐6‐substituted‐s‐triazolo[3,4‐b]‐1,3,4‐thiadiazoles
Authors: Dong Heng‐Shan , Wei Kun , Wang Qing‐Lian , Quan Bin , Zhang Zi‐Yi
Published: May 2015

Several 3‐[5‐methyl‐1‐(4‐methylphenyl)‐1,2,3‐triazol‐4‐yl]‐6‐substituted‐1,3,4‐triazolo[3,4‐b]‐1,3,4‐thiadiazoles have been synthesized and the structures of these compounds were established by elemental analysis, MS, IR and 1H NMR spectral data.
Synthesis and Some Reactions of Quinoxalinecarboazides
Authors: Moustafa O. S.
Published: May 2015

Chlorination of ethyl(quinoxalin‐2(1H)one)‐3‐carboxylate 1 gave ethyl (2‐chloroquinoxaline)‐3‐carboxylate 2;thionation of 1 by P2S5 or 2 by thiourea yielded the same product 3. Reaction of chloro compound 2 or thiocompound 3 with hydrazine hydrate gave pyrazolylquinoxaline 4. The reaction of ester 1 with thiourea or hydrazine hydrate afforded pyrimido quinoxaline 5 or carbohydrazide 6; the reaction of 6 with carbon disulfide in basic medium followed by alkylation afforded oxadiazoloquinoxaline derivatives 7, 8a,b. Carboazide 9 was produced by reaction of 5 with nitrous acid. Compound 9 on heating in an inert solvent, with or without amines, in alcohols or hydrolysis in H2O undergoes Curtius rearrangments to yield 10‐13. Reaction of 13 with thiosemicarbazide gave triazoloquinoxaline 14 which on reaction with alkylhalides or hydrazine hydrate yielded 15a‐c while hydrolysis of 13 gave 3‐aminoquinoxalinone 16 which was used as an intermediate to produce 17‐20.
Sesquiterpenoids and Diterpenoids from the Liverwort Heteroscyphus Coalitus
Authors: Jong Jing‐Rong , Wu Chia‐Li
Published: May 2015

Thirteen specimens of Heteroscyphus coalitus were chemically examined. Among the isolated compounds, 1‐hydroxyaromadendr‐4‐en‐3‐one has not been reported previously. A third new chemotype with kauranoids as the major constituents for the liverwort H. coalitus was identified.
Chemical Vapor Deposition of SnO2 Thin Films from Bis(β‐diketonato)tin Complexes
Authors: Chi Kai‐Ming , Lin Chia‐Ch'i , Lu Ya‐Hui , Liao Ju‐Hsiou
Published: May 2015

A series of bis(β‐diketonato)tin compounds have been systematically synthesized and examined as precursors for chemical vapor deposition of SnO2 thin films. These complexes were characterized by elemental analyses and NMR, IR and mass spectroscopic methods. X‐ray single‐crystal determination of Sn(tfac)2 reveals that the complex possesses a distorted trigonal bipyramidal structure. The SnO2 films can be deposited on the substrates such as silicon, titanium nitride, and glass by using Sn(hfac)2, Sn(tfac)2 and Sn(acac)2 as CVD precursors at deposition temperatures of 300‐600°C with a carrier gas of O2. The deposition rates range from 20 to 600 Å/min. Deposited films have been characterized by XRD, SEM, AFM, AES and AAS analyses.
Kinetic Study of the Ce(III)‐, Mn(II)‐, or Ferroin‐Catalyzed Belousov‐Zhabotinsky Reaction with Allylmalonic Acid
Authors: Yu Yueh‐O , Jwo Jing‐Jer
Published: May 2015

In a stirred batch experiment and under aerobic conditions, ferroin (Fe(phen)32+) behaves differently from Ce(III) or Mn(II) ion as a catalyst for the Belousov‐Zhabotinsky (BZ) reaction with allylmalonic acid (AMA). The effects of bromate ion, AMA, metal‐ion catalyst, and sulfuric acid on the oscillating pattern were investigated. The kinetics of the reaction of AMA with Ce(IV), Mn(III), or Fe(phen)33+ ion was studied under aerobic or anaerobic conditions. The order of reactivity of metal ions toward reaction with AMA is Fe(phen)33+ > Mn(III) > Ce(IV) under aerobic conditions whereas it is Mn(III) > Ce(IV) > Fe(phen)33+ under anaerobic conditions. Under aerobic or anaerobic conditions, the order of reactivity of RCH(CO2H)2 (R = H (MA), Me (MeMA), Et (EtMA), allyl (AMA), n‐Bu (BuMA), Ph (PhMA), and Br (BrMA)) is PhMA > MA > BrMA > AMA > MeMA > EtMA > BuMA toward reaction with Ce(IV) ion and it is MA > PhMA > BrMA > MeMA > AMA > EtMA > BuMA toward reaction with Mn(III) ion. Under aerobic conditions, the order of reactivity of RCH(CO2H)2 toward reaction with Fe(phen)33+ ion is PhMA > BrMA > (MeMA, AMA) > (BuMA, EtMA) > MA. The experiment results are rationalized.
Cholesterol Monohydrate Dissolution in Bile Salt‐Lecithin Solutions
Authors: Liu Chen‐Lun , Hsu Chi‐Feng
Published: May 2015

A modified dissolution rate equation was used to quantitatively investigate the contribution of simple bile salt (BS) micelles and mixed BS‐lecithin (L) micelles to a cholesterol monohydrate (ChM) dissolution. Using a least‐squares technique to assess the relationship between the ChM dissolution rate and BS concentration at a constant L concentration, good curve‐fittings were obtained when the BS monomer concentration was set to equal the critical micellar concentration (CMC). For taurochenodeoxycholate (TCDC), a dihydroxy BS, the resulting values of parameters show that the simple TCDC micelle rate constant (ks) increases, but the mixed TCDC‐L micelle rate constant (kM) decreases with increasing L concentrations. As for taurocholate (TC), a tri‐hydroxy BS, a ChM dissolution study was conducted over the initial 2 hour period in different TC‐L solutions. A similar curve‐fitting analysis revealed that the simple TC micelle ks is independent of L concentration and is much higher than the kM of mixed TC‐L micelles. Moreover, the outcome of the analysis supports previously reported equilibrium dialysis study results concerning the BS to L ratio of mixed BS‐L micelles. According to the collision theory, the resulting ks and kM values are interpreted.
Alcohol Dehydrations over ZSM‐5 Type Zeolites, Montmorillonite Clays and Pillared Montmorillonites
Authors: Lin Hung‐En , Ko An‐Nan
Published: May 2015

The reactions of aliphatic alcohols (ethanol, 1‐propanol and 2‐propanol) were studied at 1 atm and 150–300°C by using ZSM‐5 type zeolites, montmorillonites, and pillared montmorillonites. With H‐ZSM‐5 (X) Y zeolites, the total number of acid sites increases with a decrease of Si02/Al2O3molar ratio (X) and calcining temperature (Y). In addition, apparent increase in the ratio of strong to weak acid sites occurs with increasing X or decreasing Y. The acidities of M‐ZSM‐5 (51) 600 zeolites follow the sequence: Li = Na < K < Cs. Pillared clays exhibit both larger surface areas and more acid sites than the clays. The alcohol conversions decrease in the order of 2‐propanol < 1‐propanol < ethanol, in accordance with the relative stabilities of the corresponding carbenium ions. The catalytic activities are parallel to the total number of catalyst acid sites and the reaction temperature. Favorable formations of ethers are observed at low reaction temperature and small contact time on a catalyst with weak acid strength. Simple consecutive reactions and combined pathway of parallel and consecutive reactions are proposed, respectively, for the dehydration of ethanol and for those of 1‐propanol and 2‐propanol.
Synthesis and Antibacterial Activity of s‐Triazoles, s‐Triazolo[3,4‐b]‐1,3,4‐thiadiazines and s‐Triazolo[3,4‐b]‐1,3,4‐thiadiazoles of 5‐Methylisoxazole
Authors: Hui Xin‐Ping , Zhang Lin‐Mei , Zhang Zi‐Yi , Wang Qin , Wang Fang
Published: May 2015

The condensation of 4‐amino‐5‐mercapto‐3‐(5‐methylisoxazol‐3‐yl)‐1,2,4‐triazole with substituted phenacyl bromide, aldehydes, p‐bromophenylisothiocyanate, aromatic carboxylic acids and oxalic acid, is described. The antibacterial activity of representative compounds was evaluated.
Picosecond Spectroscopic Studies of Tautomers of a Bisazo Compound in Solutions
Authors: Karpicz Renata , Gulbinas Vidmantas , Undzenas Algimantas
Published: May 2015

Spectroscopic properties of a fluorenone‐based bisazo compound in different organic solvents have been investigated by means of the steady‐state absorption and fluorescence spectroscopy and picosecond time‐resolved absorption pump‐probe spectroscopy. The spectra of the molecules have been shown to be mainly determined by the excitations localized on individual chromophores ‐ azo fragments. Spectra of the azo‐enol and hydrazone‐quinone tautomeric forms were distinguished. Excited states of the two forms were found to relax in different ways. The hydrazone‐quinone form relaxes predominantly nonradiatively with the 400 ps time constant in α‐chloronaphthalene, resulting in the fluorescence quantum yield of the order of 10−2. The azo‐enol form relaxes via two competing ways, directly to the ground state with the time constant of the order of tens of picoseconds, or via the long‐lived intermediate state.
Development of Intense and Compact THz‐Radiation Source Using Femtosecond‐Laser Irradiated InAs Emitter in a High Magnetic Field
Authors: Ohtake Hideyuki , Ono Shingo , Sakai Masahiro , Kawahata Eiji , Kozeki Toshimasa , Murakami Hidetoshi , Liu Zhenlin , Tsukamoto Takeyo , Sarukura Nobuhiko
Published: May 2015

THz‐radiation power from femtosecond pulse irradiated InAs is found to be saturated at the magnetic field around 3T. We have found this saturation magnetic field drastically depends on geometrical layout and interesting magnetic field dependence of the center frequency for the THz radiation. Additionally, a compact THz‐radiation source using an InAs semiconductor is demonstrated with a turn‐key femtosecond fiber laser as an excitation source and a newly designed 2‐T permanent magnet. By using a newly designed magnetic circuit, a compact permanent magnet which can exceed the remanence magnetic field was obtained. This compact source is sufficiently intense for absorption spectroscopy.
Femtosecond Studies of Barrierless Rotamers in Solution
Authors: Glasbeek Max , Zhang Hong , van Der Meer Michael
Published: May 2015

Femtosecond fluorescence upconversion experiments have been performed for photoexcited auramine (a diphenylaminemethane dye) in liquid solution. Following pulsed laser excitation, the fluorescence shows a multiexponential decay with an initial fast decay of 2 ps. The lifetime of the relaxed excited state is 30 ps or longer, depending on the viscosity of the solvent. Concomitant with the initial fast decay a dynamic Stokes shift is observed. From a study of the excited state dynamics as a function of solvent viscosity it is concluded that auramine undergoes a picosecond (quasi)‐barrierless relaxation from an emissive to a non‐emissive excited state. The relaxation within the excited state arises from torsional diffusion motions of the phenyl rings of the auramine molecule.
Exciton States and Relaxation in Molecular Aggregates: Numerical Study of Photosynthetic Light Harvesting
Authors: Pullerits TÕNu
Published: May 2015

In this article we briefly review the molecular exciton theory and apply it to photosynthetic light harvesting systems. We derive expressions for exciton relaxation rates using perturbation theory in Hilbert space representation and show how the Förster equation can be obtained from a general relaxation rate expression in case of well localized excitons. A detailed analysis of the exciton level structure and wavefunctions of the ring structure is presented for diagonal and nondiagonal disorder. We conclude that the latter plays only a minor role in light‐harvesting systems. We emphasize the relaxation rate dependency on square of the energy gap, which makes the high frequency modes particularly important for the exciton relaxation. We found a reasonably good agreement between the measured and calculated relaxation rates in photosynthetic purple bacteria.
3‐Acyl‐4‐diphenylmethyl‐2‐(N‐cyanoimino)thiazolidine: An Enantioselective Acylation Reagent for Racemic Amines
Authors: Tanaka Tetsuaki , Fang Xie , Azuma Tsutomu , Uchida Shuji , Ishida Toshimasa , In Yasuko , Iwata Chuzo , Maezaki Naoyoshi
Published: May 2015

(S)‐3‐Acyl‐4‐diphenylmethyl‐2‐(N‐cyanoimino)thiazolidine was found to be an effective enantioselective acylation reagent for racemic amines. 3‐Benzoyl derivative was found to realize up to 79% ee upon acylation of (±)‐1 ‐phenylethylamine.
Fluorescence Lifetime of Tris‐(8‐Hydroquinoline) Aluminum Thin Film and Solution
Authors: Tang Kuo‐Chun , Cheng Pei‐Wen , Chien Volume , Cheng Cheu Pyeng , Cheng Po‐Yuan , Chen I‐Chia
Published: May 2015

The emission lifetime of tris‐(8‐hydroxyquinoline) aluminium (AIQ3) as a powder or a thin film from vaporization is measured at excitation wavelength ∼400 nm. According to decay curves recorded with time‐correlated single photon counting, the lifetimes are 17 and 12 ns for powder and film, respectively. Because films formed by sublimation contain microcrystals (C. W. Tang, S. A. Van Slyke and C. H. Chen, J. Appl. Phys. 65, 3610 (1989)), the measured lifetime reflects the structure and quality of the film. Decay curves of electronically excited AIQ3 dissolved in methanol, ethanol, acetonitrile, trichloromethane and benzene are measured; the lifetimes are 9.3, 11, 9.9, 18 and 20 ns, respectively. The lifetime of excited AIQ3 decreases with increasing solvent polarity; this trend is attributed to a dipole‐dipole interaction associated with relaxation of AIQ3. The quantum yield of fluorescence of AlQ3 in ethanol is measured to be 9.4 %.
Calculated Life Times of the First (v=1) Hydrogen Stretching Excited State on Hydrogen‐Covered H/Ge(111 )Germanium Surface
Authors: Hong Sho‐Ching , Ho Ming‐Shun , Lu Hsiu‐Feng , Sun Ying‐Chieh
Published: May 2015

In the present study, were port the calculated life times of the first hydrogen stretching excited state on a hydrogen‐covered H/Ge(111) germanium surface using molecular dynamics simulation based on the Bloch‐Redfield the ory. The life time was found to be 20 mi cro sec onds at room temperature, four or derslon ger than the hydrogen stretches on aH/Si(111) silicon surface. In addition, the calculations for the Ge‐D and Ge‐T stretches gave life times in the time scale of hundreds and tens of nano seconds, respectively, at room temperature. The thermal effect and an effect of the Ge‐Ge‐H bending frequency in the calculated life times are discussed.
Chemical Constituents from Annona Glabra III
Authors: Chang Fang‐Rong , Chen Chung‐Yi , Hsieh Tian‐Jye , Cho Chun‐Ping , Wu Yang‐Chang
Published: May 2015

Twenty compounds including a dioxoaporphine, annobraine (1); two oxoaporphines, liriodenine (2) and lysicamine (3); five aporphines, (‐)‐nornuciferine (4), (‐)‐anonaine (5), (‐)‐N‐formylanonaine (6), (‐)‐asimilobine (7) and (+)‐nordomesticine (8); one proaporphine, (+)‐stepharine (9); two protoberberines, (‐)‐kikemanine (10) and dehydrocorydalmine (11); one azaanthraquinone, 1‐aza‐4‐methyl‐2‐oxo‐1,2‐dihydro‐9,10‐anthracenedione (12); two amides, N‐trans‐feruloyltyramine (13) and N‐p‐coumaroyltyramine (14); one ionone, blumenol A (15); and five steroids, β‐sitosterol (16), stigmasterol (17), β‐sitosteryl‐D‐glucoside (18), stigmasteryl‐D‐glucoside (19) and 6‐O‐palmitoyl‐β‐sitosteryl‐D‐glucoside (20), were isolated from the fruits and stems of Annona glabra. Among them, 1 is a novel dioxoaporphine alkaloid and 12 was obtained for the first time from natural sources. These compounds were characterized and identified by physical and spectral evidence.
A Versatile Diquinane from Fulvene as a Building Block in Natural Product Synthesis II. A Facile Synthesis of Iridoids 10‐Deoxygeniposide, Mussaenoside, and 8‐epi‐Loganin
Authors: Tai Huo‐Mu , Yang Chau‐Chen
Published: May 2015

A formal total synthesis of 10‐deoxygeniposide (4), Mussaenoside (5), and 8‐epi‐loganin (6) from a versatile diquinane 3 is described.