bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diastereoselective and Enantioselective Epoxidation of Acyclic β‐Trifluoromethyl‐β,β‐Disubstituted Enones by Hydrogen Peroxide with a Pentafluorinated Quinidine‐Derived Phase‐Transfer Catalyst
Authors: Wu Shaoxiang , Pan Dong , Cao Chengyao , Wang Qi , Chen Fu‐Xue 
Published: July 2013

AbstractAn efficient catalytic asymmetric epoxidation of β‐trifluoromethyl‐β,β‐disubstituted unsaturated ketones has been achieved by a pentafluorine‐substituted phase‐transfer catalyst with hydrogen peroxide (30%). Thus, the β‐trifluoromethyl‐α,β‐epoxy ketones with a quaternary carbon centre were obtained in excellent diastereoselectivities (up to 100:1 dr) and excellent enantioselectivities (up to 99.7% ee). Low catalyst loading, recycle of catalyst, environmentally benign oxidant and easy transformation of the epoxides into medicinally important trifluoromethylated intermediate make our protocol much more practical.
Calcium‐Catalyzed Cycloisomerization of Enynes
Authors: Meyer Vera J. , Fu Liang , Marquardt Fabian , Niggemann Meike 
Published: July 2013

AbstractA cycloisomerization of enynes with a benign calcium catalyst is presented exploring a complementary reactivity to that usually found in transition and noble metal‐catalyzed reactions. Thereby, a systematic investigation of the π‐activation of alkynes with reactive carbocations has been realized and ketones of various ring sizes were easily accessed. We are certain that these basic investigations will pave the way for the elaboration of further reactions based on the reaction principles discovered in the area of noble metal catalysis.
Room Temperature Ambient Pressure (RTAP)‐Hydroformylation in Water Using a Self‐Assembling Ligand
Authors: Straub Alexander T. , Otto Marina , Usui Ippei , Breit Bernhard 
Published: July 2013

AbstractWe herein demonstrate a hydroformylation at room temperature and ambient pressure (RTAP) using our Rh/6‐DPPon (1) system in aqueous media. The hydrogen bonding network of the ligand backbone stays intact, exemplified by the excellent regioselectivity for the linear aldehyde. Various substrates with different functional groups (with some prone to hydrolysis) are stable under the applied conditions and can undergo hydroformylation resulting in good yields.
Gold(III) Chloride‐Catalyzed 6‐endo‐trig Oxa‐Michael Addition Reactions for Diastereoselective Synthesis of Fused Tetrahydropyranones
Authors: Ciesielski Jennifer , Lebœuf David , Stern Harry A. , Frontier Alison J. 
Published: July 2013

AbstractAlkynones were treated with boron trifluoride diethyl etherate to generate β‐iodoallenolates, which underwent intramolecular aldol reactions to produce cycloalkenyl alcohols. Diastereoselective oxa‐Michael ring closure could then be induced by treatment with a catalytic amount of gold(III) chloride, affording highly functionalized tetrahydropyranone‐containing ring systems.
Triarylaminium Salt‐Initiated Aerobic Double Friedel–Crafts Reaction of Glycine Derivatives with Indoles
Authors: Huo Congde , Wang Cheng , Sun Chougu , Jia Xiaodong , Wang Xicun , Chang Wenju , Wu Mingxia 
Published: July 2013

AbstractA novel and efficient stable radical cation triarylaminium salt‐catalyzed aerobic double Friedel–Crafts alkylation reaction of glycine derivatives with indoles has been developed. The reaction was performed in the absence of any other additives under mild conditions and only requires an air atmosphere (or oxygen, 1 atm) as co‐oxidant.
A Catalytic Michael/Horner–Wadsworth–Emmons Cascade Reaction for Enantioselective Synthesis of Thiochromenes
Authors: Choudhury Abhijnan Ray , Mukherjee Santanu 
Published: July 2013

AbstractA catalytic enantioselective sulfa‐Michael/Horner–Wadsworth–Emmons reaction cascade has been developed, taking advantage of phosphonate as an electrophilic activator and a traceless binding site. Using a chiral bifunctional urea derivative as the catalyst, a variety of aryl and heteroaryl substituted thiochromenes was obtained in excellent yield with a high level of enantioselectivity.
Synthesis of 3,4‐Disubstituted Quinolin‐2‐(1H)‐ones via Palladium‐Catalyzed Decarboxylative Arylation Reactions
Authors: Carrër Amandine , Brion Jean‐Daniel , Messaoudi Samir , Alami Mouad 
Published: July 2013

AbstractThe Pd‐catalyzed decarboxylative cross‐coupling reaction of 4‐substituted quinolin‐2(1H)‐one‐3‐carboxylic acids with (hetero)aryl halides is described. With palladium(II) bromide and triphenylarsine ligand as the catalyst system, a variety of 4‐substituted 3‐(hetero)aryl quinolin‐2(1 H)‐ones and related heterocycles, such as 4‐substituted 3‐arylcoumarins can be prepared in good to excellent yields.
Synthesis of Well‐Defined Diphenylvinyl(cyclopropyl)phosphine‐Palladium Complexes for the Suzuki–Miyaura Reaction and Buchwald–Hartwig Amination
Authors: Yokoyama Naota , Nakayama Yuji , Nara Hideki , Sayo Noboru 
Published: July 2013

AbstractThe well‐defined diphenylvinylphosphine‐palladium complex 1 and the diphenylcyclopropylphosphine‐palladium complex 2 were successfully synthesized. The crystal structures of these complexes were obtained by X‐ray crystallographic analysis. Both complexes were air‐ and moisture‐stable, and could be prepared on a gram scale. These palladium complexes catalyzed the Suzuki–Miyaura reaction of aryl bromides [turnover numbers (TON) up to 196,000] and aryl chlorides (TON up to 50,000). Furthermore, complex 2 catalyzed the Buchwald–Hartwig amination of aryl chlorides and aromatic/aliphatic amines with a low catalyst loading. These complexes showed different reactivities for the coupling of 2‐chloropyridine, and the origin of this difference is discussed.
Adaptive deep brain stimulation in advanced Parkinson disease
Authors: Little Simon , Pogosyan Alex , Neal Spencer , Zavala Baltazar , Zrinzo Ludvic , Hariz Marwan , Foltynie Thomas , Limousin Patricia , Ashkan Keyoumars , FitzGerald James , Green Alexander L. , Aziz Tipu Z. , Brown Peter 
Published: July 2013

ObjectiveBrain–computer interfaces (BCIs) could potentially be used to interact with pathological brain signals to intervene and ameliorate their effects in disease states. Here, we provide proof‐of‐principle of this approach by using a BCI to interpret pathological brain activity in patients with advanced Parkinson disease (PD) and to use this feedback to control when therapeutic deep brain stimulation (DBS) is delivered. Our goal was to demonstrate that by personalizing and optimizing stimulation in real time, we could improve on both the efficacy and efficiency of conventional continuous DBS.MethodsWe tested BCI‐controlled adaptive DBS (aDBS) of the subthalamic nucleus in 8 PD patients. Feedback was provided by processing of the local field potentials recorded directly from the stimulation electrodes. The results were compared to no stimulation, conventional continuous stimulation (cDBS), and random intermittent stimulation. Both unblinded and blinded clinical assessments of motor effect were performed using the Unified Parkinson's Disease Rating Scale.ResultsMotor scores improved by 66% (unblinded) and 50% (blinded) during aDBS, which were 29% (p = 0.03) and 27% (p = 0.005) better than cDBS, respectively. These improvements were achieved with a 56% reduction in stimulation time compared to cDBS, and a corresponding reduction in energy requirements (p < 0.001). aDBS was also more effective than no stimulation and random intermittent stimulation.InterpretationBCI‐controlled DBS is tractable and can be more efficient and efficacious than conventional continuous neuromodulation for PD. Ann Neurol 2013;74:449–457
Effect of drug loading and laser surface melting on drug release profile from biodegradable polymer
Authors: Hsu Shan‐Ting , Yao Y. Lawrence 
Published: July 2013

ABSTRACTThe biodegradable polymer such as poly(l‐lactic acid) is promising in drug delivery applications because it allows for drug release in a controlled manner. In a polymer‐based drug delivery system, drug release is controlled by polymer degradation and drug loading concentration. In this study, effect of drug concentration on drug release profile is investigated through polymer crystallinity, chain mobility, and polymer degradation, as characterized by the wide‐angle X‐ray diffraction, differential scanning calorimetry, and gel permeation chromatography, respectively. The addition of drug has been shown to accelerate polymer degradation and drug release rate. With a low drug concentration, the slow polymer degradation kinetics results in an induction period of drug release, during which a limited amount of drug is released. The induction period is undesirable because it delays drug release and effectiveness. Since drug release is controlled by polymer degradation, which is a function of polymer crystallinity, laser surface melting is conducted to reduce polymer surface crystallinity and modify its degradation. The effect of laser crystallinity modification on drug release is investigated. A numerical model is also implemented based on hydrolysis and diffusion mechanisms to investigate the effects of drug loading and laser surface melting on polymer degradation and drug release process. It has been demonstrated that laser treatment shortens the induction period of drug release while keeps the release rate unmodified, as desired in drug delivery applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4147–4156, 2013
Purpurides B and C, Two New Sesquiterpene Esters from the Aciduric Fungus Penicillium purpurogenum JS03‐21
Authors: Wang Hui , Wang Yi , Liu Peipei , Wang Wei , Fan Yaqin , Zhu Weiming 
Published: July 2013

AbstractPurpurides B and C (1 and 2, resp.), two new sesquiterpene alcohol esters generated from a drimane‐type sesquiterpenoid lactone and an amino acid, together with two known analogs, berkedrimane B (3) and purpuride (4), were isolated from the aciduric fungus Penicillium purpurogenum JS03‐21. Their structures were elucidated by spectroscopic analysis, X‐ray single‐crystal diffraction, and application of Marfey's method. Compounds 1–4 showed modest antifungal activities against Candida albicans with MIC values in the range of 1.2–3.3 μM. Compounds 1 and 2 showed moderate antimicrobial activities against Enterobacter aerogenes and Pseudomonas aeruginosa with MIC values in the range of 1.2–2.6 μM.
Phytochemical Fingerprints of Copaiba Oils (Copaifera multijugaHayne) Determined by Multivariate Analysis
Authors: Souza Barbosa Paula Cristina , Moreira Wiedemann Larissa Silveira , da Silva Medeiros Raquel , de Tarso Barbosa Sampaio Paulo , Vieira Gil , Florêncio da Veiga‐Junior Valdir 
Published: July 2013

AbstractOils of various species of Copaifera are commonly found in pharmacies and on popular markets and are widely sold for their medicinal properties. However, the chemical variability between and within species and the lack of standardization of these oils have presented barriers to their wider commercialization. With the aim to recognize patterns for the chemical composition of copaiba oils, 22 oil samples of C. multijuga Hayne species were collected, esterified with CH2N2, and characterized by GC‐FID and GC/MS analyses. The chromatographic data were processed using hierarchical cluster analysis (HCA) and principal component analysis (PCA). In total, 35 components were identified in the oils, and the multivariate analyses (MVA) allowed the samples to be divided into three groups, with the sesquiterpenes β‐caryophyllene and caryophyllene oxide as the main components. These sesquiterpenes, which were detected in all the samples analyzed in different concentrations, were the most important constituents in the differentiation of the groups. There was a prevalence of sesquiterpenes in all the oils studied. In conclusion, GC‐FID and GC/MS analyses combined with MVA can be used to determine the chemical composition and to recognize chemical patterns of copaiba oils.
A Novel MonoterpeneStilbene Adduct with a 4,4‐Dimethyl‐2,3‐diphenylchromane Skeleton from Artocarpus xanthocarpus
Authors: Ko Horng‐Huey , Jin Yu‐Jing , Lu Tzy‐Ming , Chen Ih‐Sheng 
Published: July 2013

AbstractArtoxanthochromane (1), a DielsAlder‐type conjugation product of 4‐isopropenylresorcinol and oxyresveratrol, was isolated from the heartwood of Artocarpus xanthocarpus and characterized. The structure of 1 was elucidated as 2‐(2,4‐dihydroxyphenyl)‐3‐(3,5‐dihydroxyphenyl)‐7‐hydroxy‐4,4‐dimethylchromane by 1D‐ and 2D‐NMR spectroscopy, and other spectral evidences. A plausible metabolic mechanism was proposed to illustrate the biosynthetic pathway of artoxanthochromane. This compound exhibited mild mushroom tyrosinase inhibitory, and weak free radical‐scavenging activities on ABTS+. and superoxide anion (O$\rm{{_{2}^{-{^\cdot} }}}$) free radicals.
Diastereoselective Synthesis of a Lilac Aldehyde Isomer and Its Electrophysiological Detection by a Moth
Authors: Schneider Marc‐André , Dötterl Stefan , Seifert Karlheinz 
Published: July 2013

AbstractThe monoterpene lilac aldehyde (=2‐(5‐ethenyl‐5‐methyloxolan‐2‐yl)propanal) is a widespread flower scent. Lilac aldehyde is emitted in high amounts from nocturnal plant species, and it is highly attractive to nocturnal moth pollinators, such as Hadena bicruris, the pollinating seed predator of Silene latifolia. Lilac aldehyde possesses three stereogenic centers and can occur in eight stereoisomers which induce different antennal responses in H. bicruris. The distribution pattern of stereoisomers differs among plant species, and if H. bicruris has different receptors for detecting different isomers, it may use these differences to discriminate flowers of S. latifolia hosts from flowers of non‐host plants. To investigate the question whether the moths have in their antennae one olfactory receptor or several different receptors for the detection of the single lilac aldehyde isomers, (2S,2′S,5′S)‐lilac aldehyde was diastereoselectively synthesized. (2S,2′S,5′S)‐Lilac aldehyde and its isomeric mixture were tested electrophysiologically on antennae of H. bicruris. The results displayed antennal responses, which are characteristic for a single receptor that detects the different lilac aldehyde isomers.
A New Cytotoxic Carbazole Alkaloid and Two New Other Alkaloids from Clausena excavata
Authors: Peng Wen‐Wen , Zeng Guang‐Zhi , Song Wei‐Wu , Tan Ning‐Hua 
Published: July 2013

AbstractOne new carbazole alkaloid, excavatine A (1), and two additional new alkaloids, excavatine B (2) and excavatine C (3), were isolated from the stems and leaves of Clausena excavata Burm.f. (Rutaceae). Their structures were determined on the basis of detailed spectroscopic analyses, especially 2D‐NMR and HR‐EI‐MS data. Compounds 1–3 were tested for their cytotoxic activities against A549, HeLa, and BGC‐823 cancer cell lines, and for their antimicrobial activities against Candida albicans and Staphylococcus aureus. Only 1 exhibited cytotoxicity against A549 and HeLa cell lines with the IC50 values of 5.25 and 1.91 μg/ml, respectively.
Unusual Secondary Metabolites from Astragalus halicacabusLam.
Authors: Djimtombaye Basile‐Jimmy , Alankuş‐Çalışkan Özgen , Gülcemal Derya , Khan Ikhlas A. , Anıl Hüseyin , Bedir Erdal 
Published: July 2013

AbstractFrom the whole plant of Astragalus halicacabus (Sect. Halicacabus), a new cycloartane‐type glycoside, (20R,24S)‐3‐O‐[α‐L‐arabinopyranosyl‐(1→2)‐β‐D‐xylopyranosyl]‐20,24‐epoxy‐16‐O‐β‐D‐glucopyranosyl‐3β,6α,16β,25‐tetrahydroxycycloartane, and a new glycoside, 3‐O‐[β‐D‐apiofuranosyl‐(1→2)‐β‐D‐glucopyranosyl]maltol were isolated together with seven known cycloartane‐type glycosides, i.e., cyclocanthoside D, askendosides D, F, and G, cyclosieversioside G, cyclostipuloside A, elongatoside, and a known maltol glucoside, 3‐O‐β‐D‐glucopyranosylmaltol. The structures were elucidated by means of high‐resolution mass spectrometry, and extensive 1D‐ and 2D‐NMR spectroscopic analysis. This is the first phytochemical work on A. halicacabus, and a maltol glycoside was encountered for the first time in the Leguminosae family.
Cytotoxic Activities of Amino Acid‐Conjugate Derivatives of Abietane‐Type Diterpenoids against Human Cancer Cell Lines
Authors: Ukiya Motohiko , Kawaguchi Takuma , Ishii Kenta , Ogihara Eri , Tachi Yosuke , Kurita Masahiro , Ezaki Yoichiro , Fukatsu Makoto , Kushi Yasunori , Akihisa Toshihiro 
Published: July 2013

AbstractNine amino acid conjugate derivatives, each 2–10 and 12–20, were prepared from abietic acid (1) and dehydroabietic acid (11), respectively, and they were evaluated for their cytotoxicities against four human cancer cell lines, i.e., leukemia (HL60), lung (A549), stomach (AZ521), and breast (SK‐BR‐3). All compounds showed cytotoxicities against HL60 with IC50 values in the range of 2.3–37.3 μM. In addition, most of the derivatives exhibited moderate cytotoxicities against the other cancer cell lines. Among the derivatives, methyl N‐[18‐oxoabieta‐8,11,13‐trien‐18‐yl]‐L‐tyrosinate (19) exhibited potent cytotoxic activities against four cancer cell lines with IC50 values of 2.3 (HL60), 7.1 (A549), 3.9 (AZ521), and 8.1 μM (SK‐BR‐3). Furthermore, all derivatives were shown to possess high selective cytotoxic activities for leukemia cells, since they exhibited only weak cytotoxicities against normal lymphocyte cell line RPMI1788.
A Silyliumylidene Cation Stabilized by an Amidinate Ligand and 4‐Dimethylaminopyridine
Authors: Yeong Hui‐Xian , Xi Hong‐Wei , Li Yongxin , Lim Kok Hwa , So Cheuk‐Wai 
Published: July 2013

AbstractThe synthesis and reactivity of a silyliumylidene cation stabilized by an amidinate ligand and 4‐dimethylaminopyridine (DMAP) are described. The reaction of the amidinate silicon(I) dimer [LSi:]2 (1; L=PhC(NtBu)2) with one equivalent of N‐trimethylsilyl‐4‐dimethylaminopyridinium triflate [4‐NMe2C5H4NSiMe3]OTf and two equivalents of DMAP in THF afforded [LSi(DMAP)]OTf (2). The ambiphilic character of 2 is demonstrated from its reactivity. Treatment of 2 with 1 in THF afforded the disilylenylsilylium triflate [L′2(L)Si]OTf (3; L′=LSi:) with the displacement of DMAP. The reaction of 2 with [K{HB(iBu)3}] and elemental sulfur in THF afforded the silylsilylene [LSiSi(H){(NtBu)2C(H)Ph}] (4) and the base‐stabilized silanethionium triflate [LSi(S)DMAP]OTf (5), respectively. Compounds 2, 3, and 5 have been characterized by X‐ray crystallography.
Fluorescent Hydroxylamine Derived from the Fragmentation of PAMAM Dendrimers for Intracellular Hypochlorite Recognition
Authors: Wu Te‐Haw , Liu Ching‐Ping , Chien Chih‐Te , Lin Shu‐Yi 
Published: July 2013

AbstractHerein, a promising sensing approach based on the structure fragmentation of poly(amidoamine) (PAMAM) dendrimers for the selective detection of intracellular hypochlorite (OCl−) is reported. PAMAM dendrimers were easily disrupted by a cascade of oxidations in the tertiary amines of the dendritic core to produce an unsaturated hydroxylamine with blue fluorescence. Specially, the novel fluorophore was only sensitive to OCl−, one of reactive oxygen species (ROS), resulting in an irreversible fluorescence turn‐off. The fluorescent hydroxylamine was selectively oxidised by OCl− to form a labile oxoammonium cation that underwent further degradation. Without using any troublesomely synthetic steps, the novel sensing platform based on the fragmentation of PAMAM dendrimers, can be applied to detect OCl− in macrophage cells. The results suggest that the sensing approach may be useful for the detection of intracellular OCl− with minimal interference from biological matrixes.
Enantio‐ and Regioselective Conjugate Addition of Organometallic Reagents to Linear Polyconjugated Nitroolefins
Authors: Tissot Matthieu , Alexakis Alexandre 
Published: July 2013

AbstractThe copper‐catalysed conjugate addition of trialkylaluminium and dialkylzinc reagents to polyconjugated nitroolefins (nitrodiene and nitroenyne derivatives) is reported. A reversed Josiphos ligand L7 allows for the selective 1,4‐ or 1,6‐addition with high enantioselectivities.
Super‐Hydrated Zeolites: Pressure‐Induced Hydration in Natrolites
Authors: Seoung Donghoon , Lee Yongmoon , Kao Chi‐Chang , Vogt Thomas , Lee Yongjae 
Published: July 2013

AbstractHigh‐pressure synchrotron X‐ray powder diffraction studies of a series of alkali‐metal‐exchanged natrolites, A16Al16Si24O80⋅n H2O (A=Li, K, Na, Rb, and Cs and n=14, 16, 22, 24, 32), in the presence of water, reveal structural changes that far exceed what can be achieved by varying temperature and chemical composition. The degree of volume expansion caused by pressure‐induced hydration (PIH) is inversely proportional to the non‐framework cation radius. The expansion of the unit‐cell volume through PIH is as large as 20.6 % in Li‐natrolite at 1.0 GPa and decreases to 6.7, 3.8, and 0.3 % in Na‐, K‐, and Rb‐natrolites, respectively. On the other hand, the onset pressure of PIH appears to increase with non‐framework cation radius up to 2.0 GPa in Rb‐natrolite. In Cs‐natrolite, no PIH is observed but a new phase forms at 0.3 GPa with a 4.8 % contracted unit cell and different cation–water configuration in the pores. In K‐natrolite, the elliptical channel undergoes a unique overturn upon the formation of super‐hydrated natrolite K16Al16Si24O80⋅32 H2O at 1.0 GPa, a species that reverts back above 2.5 GPa as the potassium ions interchange their locations with those of water and migrate from the hinge to the center of the pores. Super‐hydrated zeolites are new materials that offer numerous opportunities to expand and modify known chemical and physical properties by reversibly changing the composition and structure using pressure in the presence of water.
Synthesis of Polycyclic Aminocyclobutane Systems by the Rearrangement of N‐(ortho‐Vinylphenyl) 2‐Azabicyclo[3.1.0]hexane Derivatives
Authors: Wasilewska Agnieszka , Woźniak Bartosz A. , Doridot Gabriel , Piotrowska Kamila , Witkowska Natalia , Retailleau Pascal , Six Yvan 
Published: July 2013

AbstractThe acid‐catalysed thermal rearrangements of a family of N‐aryl 2‐azabicyclo[3.1.0]hexanes is described. These substrates, designed in such a way that the aromatic system is conjugated with an alkene group located at the ortho position relative to the nitrogen atom, have been prepared by using an intramolecular Kulinkovich–de Meijere reaction. The rearrangements can then be conducted either under standard thermal conditions or with microwave activation. Depending on the conditions applied and the substitution pattern, dihydroquinoline or polycyclic aminocyclobutane derivatives can be obtained. A mechanistic discussion is provided, with the proposition of the initial protonation of the aminocyclopropane moiety to give an iminium intermediate. By analogy with related intermolecular reactions, the involvement of electrocyclic reactions among the series of elementary steps that follow is put forward.