bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metallopolymers Featuring Boratabenzene Iron Complexes
Authors: Pammer Frank , Lalancette Roger A. , Jäkle Frieder 
Published: September 2011

AbstractBoratabenzene‐derived metallocene analogues are introduced as versatile new building blocks for metallopolymers. Bis(borinato)iron(II) complexes of the type Fe(C5H5BR)2 (R: CCH, CCSiMe3, 4‐(1‐benzyl‐1,2,3‐triazolyl) were synthesized and spectroscopically, structurally, and electrochemically characterized. Polymerization via Sonogashira–Hagihara coupling of the alkynyl‐substituted derivative Fe(C5H5BCCH)2 with 2,5‐bis(dodecyloxy)‐1,4‐diiodobenzene yields a film‐forming polymer in 50–69 % yield. Polymer batches were obtained with number‐average molecular weights (Mn) of 11.7 and 20.5 kDa and polydispersity indices (PDI) of 1.55 and 2.65, respectively, as determined by gel permeation chromatography relative to polystyrene standards. Click‐type polymerization of Fe(C5H5BCCH)2 through azide–alkyne cycloaddition with 1,4‐bis(4‐azidobutoxy)benzene gives the corresponding metallopolymer with an Mn of 5.7 kDa and a PDI of 2.29 in 87 % yield.
Biomolecule‐Assisted Route to Prepare Titania Mesoporous Hollow Structures
Authors: Ding Shangjun , Wang Yaoming , Hong Zhanglian , Lü Xujie , Wan Dongyun , Huang Fuqiang 
Published: September 2011

AbstractAmino acids, as a particularly important type of biomolecules, have been used as multifunctional templates to intelligently construct mesoporous TiO2 hollow structures through a simple solvothermal reaction. The structure‐directing behaviors of various amino acids were systematically investigated, and it was found that these biomolecules possess the general capability to assist mesoporous TiO2 hollow‐sphere formation. At the same time, the nanostructures of the obtained TiO2 are highly dependent on the isoelectric points (pI) of amino acids. Their molecular‐structure variations can lead to pI differences and significantly influence the final TiO2 morphologies. Higher‐pI amino acids (e.g., L‐lysine and L‐arginine) have better structure‐directing abilities to generate nanosheet‐assembled hollow spheres and yolk/shell structures. The specific morphologies and mesopore size of these novel hollow structures can also be tuned by adjusting the titanium precursor concentration. Heat treatment in air and vacuum was further conducted to transform the as‐prepared structures to porous nanoparticle‐assembled hollow TiO2 and TiO2/carbon nanocomposites, which may be potentially applied in the fields of photocatalysts, dye‐sensitized solar cells, and Li batteries. This study provides some enlightenment on the design of novel templates by taking advantage of biomolecules.
The Nature of Unsupported Uranium–Ruthenium Bonds: A Combined Experimental and Theoretical Study
Authors: Gardner Benedict M. , Patel Dipti , Cornish Andrew D. , McMaster Jonathan , Lewis William , Blake Alexander J. , Liddle Stephen T. 
Published: September 2011

AbstractFour new uranium–ruthenium complexes, [(TrenTMS)URu(η5‐C5H5)(CO)2] (9), [(TrenDMSB)URu(η5‐C5H5)(CO)2] (10), [(TsTolyl)(THF)URu(η5‐C5H5)(CO)2] (11), and [(TsXylyl)(THF)URu(η5‐C5H5)(CO)2] (12) [TrenTMS=N(CH2CH2NSiMe3)3; TrenDMSB=N(CH2CH2NSiMe2tBu)3]; TsTolyl=HC(SiMe2NC6H4‐4‐Me)3; TsXylyl=HC(SiMe2NC6H3‐3,5‐Me2)3], were prepared by a salt‐elimination strategy. Structural, spectroscopic, and computational analyses of9–12shows: i) the formation of unsupported uranium–ruthenium bonds with no isocarbonyl linkages in the solid state; ii) ruthenium–carbonyl backbonding in the [Ru(η5‐C5H5)(CO)2]−ions that is tempered by polarization of charge within the ruthenium fragments towards uranium; iii) closed‐shell uranium–ruthenium interactions that can be classified as predominantly ionic with little covalent character. Comparison of the calculated URu bond interaction energies (BIEs) of9–12with the BIE of [(η5‐C5H5)3URu(η5‐C5H5)(CO)2], for which an experimentally determined URu bond disruption enthalpy (BDE) has been reported, suggests BDEs of approximately 150 kJ mol−1for9–12.
ChemInform Abstract: The Non‐Centrosymmetric Crystal Structure of Molybdenum(VI) Oxide Bromide MoO2Br2.
Authors: Schustereit Tanja , Schleid Thomas , Hartenbach Ingo 
Published: September 2011

AbstractTransparent, red, platelet‐shaped single crystals of MoO2Br2 are obtained as by‐products in the synthesis of LnBr[MoO4] (Ln: La, Gd) from mixtures of LaBr3 or GdBr3 and MoO3 (evacuated silica tubes, 820 °C).
ChemInform Abstract: Solvated Electrons in High‐Temperature Melts and Glasses of the Room‐Temperature Stable Electride [Ca24Al28O64] 4+·4e‐.
Authors: Kim Sung Wng , Shimoyama Terumasa , Hosono Hideo 
Published: September 2011

AbstractThe formation of persistent solvated electrons in both a high‐temperature melt of the title electride and its glass is demonstrated by electrical conductivity measurements, XRD, TEM, and Raman spectroscopy.
ChemInform Abstract: Suppression of Magnetic Order in Sr3Fe2O4Cl2 by Fe‐Site Substitution by Cobalt.
Authors: Dixon Edward , Hayward Michael A. 
Published: September 2011

AbstractSr3Fe2‐xCoxO4Cl2 (x = 0.2, 0.6, 0.8, 1) phases, obtained by low temperature topotactic reduction of Sr3Fe2‐xCoxO5Cl2 with LiH, are characterized by powder X‐ray and neutron diffraction, and magnetic measurements.
ChemInform Abstract: Solvothermal Synthesis and Characterization of Polyselenidoarsenate Salts of Transition Metal Complex Cations.
Authors: Jia Dingxian , Zhao Jing , Pan Yingli , Tang Weiwei , Wu Bing , Zhang Yong 
Published: September 2011

AbstractCompounds (III) and (V) crystallize in the triclinic space group P$\bar 1$ with Z = 2, (VII) in the triclinic space group P$\bar 1$ with Z = 1, and (IX) in the monoclinic space group C2 with Z = 4.
ChemInform Abstract: Indium—Sulfur Supertetrahedral Polymers Integrated with [M(phen)3]2+ Cations (M: Ni and Fe).
Authors: Zhang Xu , Luo Wen , Zhang Ya‐Ping , Jiang Jian‐Bing , Zhu Qin‐Yu , Dai Jie 
Published: September 2011

AbstractCompound (III) crystallizes in the triclinic space group P1 with Z = 1 and compounds (V) and (VI) in the monoclinic space group C2/c with Z = 4.
ChemInform Abstract: Conjugate Addition of Vinylic Organocuprates Generated via Transmetalation of Phenylseleno‐Substituted Vinylzirconates: Functionalization at the 4‐Position of Enones.
Authors: Segi Masahito , Suzuki Masahiro , Shintaku Kazuki , Maeda Hajime 
Published: September 2011

AbstractA simple and useful method for the functionalization at the 4‐position of enones is presented.
ChemInform Abstract: Enantioselecitive Synthesis of 2‐Hydroxy‐5‐methyl‐3‐hexanone.
Authors: Tian Hong‐Yu , Ye Hong‐Lin , Sun Bao‐Guo , Wang Ya‐Ling 
Published: September 2011

AbstractThe preparation of (R)‐ and (S)‐(II) via Shi′s asymmetric epoxidation yielding similar enantiotiomeric excesses but lower yields is also described.
ChemInform Abstract: Ethyl‐2‐(2‐chloroethyl)acrylate: A New Very Versatile α‐Cyclopropylester Cation Synthon. Efficient Synthesis of Cyclopropane Ester Derivatives by Michael Addition‐Induced Cyclization Reaction.
Authors: Lachia Mathilde , Iriart Sebastien , Baalouch Myriam , De Mesmaeker Alain , Beaudegnies Renaud 
Published: September 2011

AbstractThe use of title compound (I) as versatile α‐cyclopropylester cation synthon is described.
ChemInform Abstract: Mechanistic Switch via Subtle Ligand Modulation: Palladium‐Catalyzed Synthesis of α,β‐Substituted Styrenes via C—H Bond Functionalization.
Authors: Flores‐Gaspar Areli , Martin Ruben 
Published: September 2011

AbstractIt is found that Pd‐catalyzed treatment of 2‐(2‐bromoaryl)propanals can lead to benzocyclobutenones and/or substituted styrenes depending on the phosphine ligand used.
ChemInform Abstract: Asymmetric Henry Reaction by a Chiral Cu(II) Complex: A Facile Enantioselective Synthesis of (S)‐2‐Nitro‐1‐arylethanols.
Authors: Reddy Basi V. Subba , Reddy Sankham Madhusudana , Manisha Swain , Madan Chinnala 
Published: September 2011

AbstractAnhydrous Cu(OAc)2 is more effective than the monohydrate.
ChemInform Abstract: Palladium‐Catalyzed Oxidative C—H Bond Coupling of Steered Acetanilides and Aldehydes: A Facile Access to ortho‐Acylacetanilides.
Authors: Wu Yinuo , Li Baozhu , Mao Fei , Li Xingshu , Kwong Fuk Yee 
Published: September 2011

AbstractThe reaction requires excess tBuOOH to assure high yields.
ChemInform Abstract: Introduction of Azetidinimine Skeleton on C60.
Authors: Ueda Nobuaki , Nikawa Hidefumi , Takano Yuta , Ishitsuka Midori O. , Tsuchiya Takahiro , Akasaka Takeshi 
Published: September 2011

AbstractNovel C60 derivatives (III) are synthesized without causing a drastic change of the electronic properties of the fullerene cage.
ChemInform Abstract: Efficient and Mild Synthesis of Highly Substituted 2,5‐Dihydrofuran and Furan Derivatives via Stepwise Reaction.
Authors: Wang Tiantian , Liu Jia , Lv Zhiliang , Zhong Hanyu , Chen Huan , Niu Chunjuan , Li Ke 
Published: September 2011

AbstractCopper‐catalyzed reaction of butynediol (II) with alkylidenemalonates (I) affords dihydrofuran (III) derivatives under mild reaction conditions (1,2 equivalents NaH, 30‐40°C).
ChemInform Abstract: Catalytic Asymmetric Vinylogous Mannich‐Type (AVM) Reaction of Nonactivated α‐Angelica Lactone.
Authors: Zhou Lin , Lin Lili , Ji Jie , Xie Mingsheng , Liu Xiaohua , Feng Xiaoming 
Published: September 2011

AbstractThe chiral products (III) and (V) bearing adjacent quaternary and tertiary stereocenters are formed with excellent diastereo‐ and enantioselectivities.
ChemInform Abstract: Synthesis of 2‐Mercaptobenzothiazoles via DBU‐Promoted Tandem Reaction of o‐Haloanilines and Carbon Disulfide.
Authors: Wang Fei , Cai Shangjun , Wang Zhipeng , Xi Chanjuan 
Published: September 2011

AbstractThe reaction proceeds equally well for the ortho‐bromo‐ and ortho‐iodoanilines.
ChemInform Abstract: Chiral Lewis Base Assisted Broensted Acid (LBBA) Catalyzed Enantioselective Cyclization of 2‐Geranylphenols.
Authors: Sakakura Akira , Sakuma Masayuki , Ishihara Kazuaki 
Published: September 2011

AbstractThe trans‐isomers are formed with high stereoselectivities.
ChemInform Abstract: Potassium tert‐Butoxide Promoted Intramolecular Arylation via a Radical Pathway.
Authors: Roman Daniela Sustac , Takahashi Yoko , Charette Andre B. 
Published: September 2011

AbstractThe reaction of the ortho‐iodo arenes with amines, amide, ethers and benzyl moieties in the absence of any metal catalyst provides phenanthridine, benzochromene and phenanthrene products with good yields.
ChemInform Abstract: First Construction of 12H‐Thiochromeno[2,3‐b]quinolines and 5H‐Benzo[7,8]thiocino‐[2,3‐b]quinolines via Intramolecular Friedel—Crafts Reaction of Morita—Baylis—Hillman Adducts.
Authors: Zhong Weihui , Ma Wang , Liu Yanbin 
Published: September 2011

AbstractAcid‐mediated intramolecular Friedel—Crafts reaction of MBH adducts (III) and (VI) is studied.
ChemInform Abstract: Synthesis and Antibacterial Property of Pyrrolopyrano Quinolinones and Pyrroloquinolines.
Authors: Jayagobi Mathesan , Raghunathan Ragavachary , Sainath Shilpakala , Raghunathan Malathi 
Published: September 2011

AbstractThe title compounds (III), (IV), and (VI) are evaluated for their antibacterial activity against S.
ChemInform Abstract: Synthesis and Biological Evaluation of N‐Substituted Benzo[c]phenanthrolines and Benzo[c]phenanthrolinones as Antiproliferative Agents.
Authors: Genes Constance , Lenglet Gaelle , Depauw Sabine , Nhili Raja , Prado Soizic , David‐Cordonier Marie‐Helene , Michel Sylvie , Tillequin Francois , Poree Francois‐Hugues 
Published: September 2011

AbstractThe biological activity of compounds (III) and (VI) is evaluated.
ChemInform Abstract: 4‐Hydroxy‐2‐quinolones. Part 194. 1‐Hydroxy‐3‐oxo‐6,7‐dihydro‐3H,5H‐pyrido [3,2,1‐ij]quinoline‐2‐carboxylic Acid Alkylamides. Synthesis, Structure and Biological Properties.
Authors: Ukrainets I. V. , Golik N. Yu. , Andreeva K. V. , Gorokhova O. V. 
Published: September 2011

AbstractTitle compounds (V) (17 examples) are prepared starting from tetrahydroquinoline (I) by modified methods.
ChemInform Abstract: Synthesis of 2,2‐Dimethyl‐1,2‐dihydrobenzo[f]isoquinolines Displaying Antifungal Activity.
Authors: Surikova O. V. , Zachinyaeva A. V. , Mikhailovskii A. G. , Zachinyaev Ya. V. 
Published: September 2011

AbstractTitle compounds are synthesized starting from azomethine (I).
ChemInform Abstract: Synthesis and Antimicrobial Activity of Some Novel Dicationic Sulfonophanes.
Authors: Rajakumar Perumal , Satheeshkumar Chinnadurai , Mohanraj Gunasekaran , Mathivanan Narayanasamy 
Published: September 2011

AbstractSulfonophanes (V) incorporating various spacer units and imidazole as a building unit are prepared via an N‐alkylation route by capping the precyclophane (III) with suitable dibromides such as (IV).
ChemInform Abstract: Synthesis and Structure of Peri‐Substituted Boron/Pnictogen Naphthalene Derivatives.
Authors: Wade Casey R. , Saber Mohamed R. , Gabbai Francois P. 
Published: September 2011

AbstractThe reaction of heavy group 15 electrophiles (II) with the compound (I) presents the first example to afford the title compounds (III).
ChemInform Abstract: Reactions of Acyl Phosphonates with Organoaluminum Reagents: A New Method for the Synthesis of Secondary and Tertiary α‐Hydroxy Phosphonates.
Authors: Seven Ozlem , Polat‐Cakir Sidika , Hossain Md. Shakhawoat , Emrullahoglu Mustafa , Demir Ayhan S. 
Published: September 2011

AbstractTrimethylaluminum (II) and triethynylaluminum (VIII) add towards acylphosphonates (I) and (VII) at 0 °C to give the corresponding tertiary alcohols (III) and (IX), respectively.
ChemInform Abstract: New Potent Human Acetylcholinesterase Inhibitors in the Tetracyclic Triterpene Series with Inhibitory Potency on Amyloid β Aggregation.
Authors: Rouleau Julien , Iorga Bogdan I. , Guillou Catherine 
Published: September 2011

AbstractVarious compounds, e.g. (V), are synthesized from the starting compound (I) and tested in vitro for their inhibition of cholinesterases and for the ability to prevent acetylcholinesterase(AChE)‐induced amyloid β aggregation.
ChemInform Abstract: Copper Mediated Defluorinative Allylic Alkylation of Difluorohomoallyl Alcohol Derivatives Directed to an Efficient Synthetic Method for (Z)‐Fluoroalkene Dipeptide Isosteres.
Authors: Watanbe Daisuke , Koura Minoru , Saito Akio , Yanai Hikaru , Nakamura Yuko , Okada Midori , Sato Azusa , Taguchi Takeo 
Published: September 2011

AbstractCopper‐mediated defluorinative allylic alkylation of difluorohomoallyl alcohol derivatives of type (III) or (IV) is used as key step for the synthesis of (Z)‐fluoroalkene dipeptide isosters, e.g. (XI).
ChemInform Abstract: Microbial Mannosidation of Bioactive Chlorogentisyl Alcohol (I) by the Marine‐Derived Fungus Chrysosporium synchronum.
Authors: Yun Keumja , Kondempudi Chinni Mahesh , Choi Hong Dae , Kang Jung Sook , Son Byeng Wha 
Published: September 2011

AbstractCompounds (I) and its mannoside (II) exhibit significant readical‐scavenging activity against 1,1‐diphenyl‐2‐picrylhydrazyl radical (DPPH).
ChemInform Abstract: Syntheses of 2,3‐Dihydro‐1,4‐benzodioxins and Bioisosteres as Structural Motifs for Biologically Active Compounds
Authors: Cruz‐Lopez Olga , Nunez Maria C. , Conejo‐Garcia Ana , Kimatrai Maria , Campos Joaquin M. 
Published: September 2011

AbstractReview: 102 refs.
Reversible Addition‐Fragmentation Chain Transfer Polymerization Implemented as Continuous Process in CSTR and PFR at Elevated Reaction Conditions
Authors: Koch Sara C. , Busch Markus 
Published: September 2011

AbstractThe reversible addition‐fragmentation chain transfer polymerization is a very versatile type of polymerization to produce (co)polymers of well‐defined structure. However, in most cases this process has not exceeded the status of laboratory scale. Besides the major interest in developing well‐defined polymer structures in the first row, the relative low speed of polymerization may be another argument. Elevated temperature and pressure may be an option to increase the rate of polymerization to a significant level. The presented work will test for this and inspect the potential of implementing this type of polymerization into a continuous process. On a micro‐plant scale, this might be attractive to generate reasonable quantities of well‐defined (co)polymers showing low polydispersity indices.
Comparison of the impact of flow pulsations on the performance of various liquid–gas injectors in a gas–solid fluidised bed
Authors: Sabouni Rana , Berruti Franco , Briens Cedric 
Published: September 2011

AbstractThis article shows that spray nozzles pulsations can greatly improve the distribution of the sprayed liquid on fluidised bed particles, as characterised by a Nozzle Performance Index (NPI). Appropriate pulsations increased the NPI by nearly 100% under several operating conditions. This article compares four pulsating, gas atomised nozzles under various operating conditions. The performance of each nozzle was evaluated by measuring the electric conductance of a bed of silica sand particles fluidised by air, subsequent to liquid injection. Three sets of experiments were conducted to investigate the effect of operating conditions on the performance of the four gas atomised nozzles. The first set determined the effect of the liquid flowrate, the second set measured the effect of a restriction orifice on the atomisation gas line and the third set studied the effect of the atomisation air to liquid ratio. Artificial nozzle spray pulsations were found to have similar beneficial effects with the different types of gas‐atomised nozzles. © 2011 Canadian Society for Chemical Engineering
Successive linearisation analysis of unsteady heat and mass transfer from a stretching surface embedded in a porous medium with suction/injection and thermal radiation effects
Authors: Motsa S. S , Shateyi S. 
Published: September 2011

AbstractIn this study, we investigate the application of the new successive linearisation method (SLM) to the problem of unsteady heat and mass transfer from a stretching surface embedded in a porous medium with suction/injection and thermal radiation effects. The governing nonlinear momentum, energy and mass transfer equations are successfully solved numerically using the SLM approach coupled with the spectral collocation method for iteratively solving the governing linearised equations. Comparison of the SLM results for various flow parameters against numerical results and other published results, obtained using the homotopy analysis method (HAM) and Runge–Kutta methods, for related problems indicates that the SLM is a very powerful tool which is much more accurate and efficient than other methods. The SLM converges much faster than the traditional methods like the HAM and is very easy to implement. © 2011 Canadian Society for Chemical Engineering
Influence of materials dielectric properties on the petroleum oil removal from waste under microwave irradiation
Authors: Shang Hui , Guo Yonggang , Yang Xiaoqing , Zhang Wenhui 
Published: September 2011

AbstractThe effects of dielectric materials on the petroleum oil removal from solid waste under microwave heating were fully detailed within this research. The experiments clearly show that although water has high dielectric properties, it is not efficient to remove heavy oils due to its volatility. Salt water having high loss factor contributes to the oil removal at low concentration, whereas high concentration results in less. Activated carbon was proved to be more efficient for either light or heavy petroleum oils. The simulation results yielded good estimations of power density throughout the sample. The simulated temperature distribution clearly explains the experimental results and can be used to predict the efficiency of organic removal from solid wastes. © 2011 Canadian Society for Chemical Engineering
Left Ventricular Torsional Mechanics in Uncomplicated Pregnancy
Authors: Yoon Andrew J. , Song Jason , Megalla Sherry , Nazari Reza , Akinlaja Olukayode , Pollack Simcha , Bella Jonathan N. 
Published: September 2011

AbstractBackground:Alterations in left ventricular (LV) twist (torsion) and untwist have been described for a variety of physiologic and pathologic conditions. Little information is available regarding changes in these parameters during normal pregnancy.Hypothesis:Pregnancy is associated with significant changes in LV torsional mechanics.Methods:Left ventricular twist and untwist was measured in 32 pregnant females (mean gestation 199 ± 48 d) and 23 nonpregnant controls using speckle‐tracking echocardiography.Results:Left ventricular ejection fraction (68 ± 5% vs 66 ± 5%) was similar between the groups (P not significant). There was a significant increase in peak LV twist from nonpregnant controls (9.4 ± 3.7 degrees) to second‐trimester (12.0 ± 4.2 degrees) and third‐trimester subjects (12.6 ± 5.9 degrees, all P<0.05). Peak LV twist velocity was also increased in second‐ and third‐trimester groups compared with controls (94 ± 24 degrees/sec and 93 ± 30 vs 64 ± 21 degrees/sec, respectively, both P<0.05). Both peak untwist velocity and time to peak untwist velocity were not significantly different between groups (P not significant). Multiple regression analysis indicate that only systolic blood pressure (r = 0.394, P = 0.005) was an independent predictor for increased LV torsion.Conclusions:There are significant changes in LV torsional indices during the course of pregnancy, whereas untwist parameters remain unchanged. Blood pressure is independently associated with increased torsion during pregnancy. © 2011 Wiley Periodicals, Inc.The authors have no funding, financial relationships, or conflicts of interest to disclose.
Development of 2,3,5‐Triaryl‐1H‐pyrroles as Estrogen Receptor α Selective Ligands
Authors: Schäfer Anja , Wellner Anja , Strauss Martin , Wolber Gerhard , Gust Ronald 
Published: September 2011

Abstract1‐Alkyl‐2,3,5‐triaryl‐1H‐pyrroles (for which alkyl=methyl, ethyl, n‐propyl, or 2‐methylpropyl) were tested for stability, estrogen receptor (ER) binding, and inhibition of tumor cell growth. These pyrroles (type B) showed higher stability in aqueous solution than their 1,2,4‐triaryl‐1H‐pyrrole congeners (type A pyrroles), exclusive ERα binding (no ERβ interaction), and a hormonal profile of partial agonists at ERα. The most potent compound, 1‐(2‐methylpropyl)‐2,3,5‐tris(4‐hydroxyphenyl)‐1H‐pyrrole (5 d), was less active than the lead structure 1,3,5‐tris(4‐hydroxyphenyl)‐4‐propyl‐1H‐pyrazole (PPT) in MCF‐7 cells stably transfected with the plasmid EREwtcluc (MCF‐7/2a), but more potent in U2‐OS/α cells. Furthermore, 5 d showed weak anti‐estrogenic properties (IC50=310 nM). An additional propyl chain at C4 decreased the stability and pharmacological effects.
Asymmetric Synthesis and Conformational Analysis by NMR Spectroscopy and MD of Aba‐ and α‐MeAba‐Containing Dermorphin Analogues
Authors: Vandormael Bart , De Wachter Rien , Martins José C. , Hendrickx Pieter M. S. , Keresztes Attila , Ballet Steven , Mallareddy Jayapal R. , Tóth Fanni , Tóth Géza , Tourwé Dirk 
Published: September 2011

AbstractDermorphin analogues, containing a (S)‐ and (R)‐4‐amino‐1,2,4,5‐tetrahydro‐2‐benzazepin‐3‐one scaffold (Aba) and the α‐methylated analogues as conformationally constrained phenylalanines, were prepared. Asymmetric phase‐transfer catalysis was unable to provide the (S)‐α‐Me‐o‐cyanophenylalanine precursor for (S)‐α‐MeAba in acceptable enantiomeric purity. However, by using a Schöllkopf chiral auxiliary, this intermediate was obtained in 88 % ee. [(S)‐Aba 3‐Gly 4]dermorphin retained μ‐opioid affinity but displayed an increased δ‐affinity. The corresponding R epimer was considerably less potent. In contrast, the [(R)‐α‐MeAba 3‐Gly 4]dermorphin isomer was more potent than its S epimer. Tar‐MD simulations of both non‐methylated [Aba 3‐Gly 4]dermorphin analogues showed a degree of folding at the C‐terminal residues toward the N terminus of the peptide, without however, adopting a stabilized β‐turn conformation. The α‐methylated analogues, on the other hand, exhibited a type I/I′ β‐turn conformation over the α‐MeAba 3 and Gly 4 residues, which was stabilized by a hydrogen bond involving Tyr 5‐HN and D‐Ala 2‐CO.