Angewandte Chemie International Edition
Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Upcoming Hot Papers
Hot Papers are chosen by the Editors for their importance in a rapidly evolving field of high current interest. Many of the "Very Important Papers" (VIPs) would certainly qualify to be included here, but such a duplication is avoided.
Insect-Derived Proline-Rich Antimicrobial Peptides Kill Bacteria by Inhibiting Bacterial Protein Translation at the 70 S Ribosome
Andor Krizsan, Dr. Daniela Volke, Stefanie Weinert, Prof.Dr. Norbert Sträter, Dr. Daniel Knappe and Prof.Dr. Ralf Hoffmann
Lost in translation: Proline-rich antimicrobial peptides (PrAMPs) inhibit bacterial protein translation by binding to the 70S ribosome of Gram-negative bacteria. This represents a novel killing mechanism for gene-encoded antimicrobial peptides. Alanine substitutions in the peptides additionally identified specific basic and hydrophobic residues as major interaction sites, which will enable the design of optimized compounds.
Natural Product Synthesis
Enantioselective Divergent Syntheses of Several Polyhalogenated Plocamium Monoterpenes and Evaluation of Their Selectivity for Solid Tumors
Carl V. Vogel, Halina Pietraszkiewicz, Omar M. Sabry, Prof. William H. Gerwick, Dr. Frederick A. Valeriote and Prof. Christopher D. Vanderwal
Glyceraldehyde acetonide serves as a chiral glyoxal equivalent and a linchpin for the enantioselective synthesis of several acyclic polyhalogenated monoterpenes from the red algae Plocamium. Several of these compounds demonstrate selective toxicity towards solid-tumor cell lines over leukemia cell lines, as well as low-micromolar cytotoxicity towards the HCT-116 human colon carcinoma cell line.
Carbon Nanofibers Decorated with Molybdenum Disulfide Nanosheets: Synergistic Lithium Storage and Enhanced Electrochemical Performance
Fei Zhou, Dr. Sen Xin, Dr. Hai-Wei Liang, Lu-Ting Song and Prof. Dr. Shu-Hong Yu
Carbon nanofibers (CNFs) decorated with molybdenum disulfide sheets are fabricated by a facile hydrothermal process with low-cost, biomass-derived carbonaceous nanofibers as the supports. On reacting with lithium, the nanofibers undergo novel electrochemical processes that are triggered by a synergistic lithium storage effect, leading to enhanced cycling and rate performance of the lithium-ion battery.
A CXCR4-Targeted Site-Specific Antibody–Drug Conjugate
Dr. Sumith A. Kularatne, Dr. Vishal Deshmukh, Dr. Jennifer Ma, Dr. Virginie Tardif, Dr. Reyna K. V. Lim, Holly M. Pugh, Dr. Ying Sun, Anthony Manibusan, Aaron J. Sellers, Dr. Richard S. Barnett, Shailaja Srinagesh, Jane S. Forsyth, Dr. Wolf Hassenpflug, Dr. Feng Tian, Dr. Tsotne Javahishvili, Prof. Brunhilde Felding-Habermann, Prof. Brian R. Lawson, Dr. Stephanie A. Kazane and Prof. Peter G. Schultz
Hitting the mark(er): A chemically defined anti-CXCR4–auristatin antibody–drug conjugate (ADC) was produced that selectively targets and eliminates CXCR4+ metastatic cancer cells in vitro and in vivo with no significant overt toxicity. Because the CXCR4 receptor is highly expressed in the majority of metastatic cancers, a CXCR4–auristatin ADC may be useful for the treatment of a variety of metastatic malignancies.
Large-Scale Fabrication of Pseudocapacitive Glass Windows that Combine Electrochromism and Energy Storage
Peihua Yang, Peng Sun, Zhisheng Chai, Prof. Langhuan Huang, Dr. Xiang Cai, Prof. Shaozao Tan, Prof. Jinhui Song and Prof. Wenjie Mai
A pseudocapacitive glass window (15×15 cm2) is obtained by the deposition of WO3 on fluorine-doped tin oxide glass. Such smart pseudocapacitive glass windows show great potential in functioning as electrochromic windows and concurrently powering electronic devices, such as mobile phones or laptops.
Hexagonal Transition-Metal Chalcogenide Nanoflakes with Pronounced Lateral Quantum Confinement
Dr. Pere Miró, Jae Hyo Han, Prof. Dr. Jinwoo Cheon and Prof. Dr. Thomas Heine
Six-sided flakes: Transition-metal dichalcogenide nanoflakes of composition MX2 (where M=Ti, Zr and Hf; X=S and Se) grow preferentially in equilateral hexagons and exhibit a pronounced lateral quantum confinement. The hexagonal shape arises from the charge location at the edges and vertices and the resulting Coulombic repulsion.
Radical CH Functionalization of Heteroarenes under Electrochemical Control
Dr. Alexander G. O'Brien, Dr. Akinobu Maruyama, Dr. Yasuhide Inokuma, Prof. Makoto Fujita, Prof. Phil S. Baran and Prof. Donna G. Blackmond
Electrochemical reactions are shown to be effective for the CH functionalization of a number of heterocyclic substrates that are recalcitrant to conventional peroxide radical initiation conditions and of interest in medicinal chemistry. Monitoring reaction progress under electrochemical conditions provides mechanistic insight into the CH functionalization process.
Differential Reduction of CO2 by Molybdenum and Vanadium Nitrogenases
Johannes G. Rebelein, Prof. Dr. Yilin Hu and Prof. Dr. Markus W. Ribbe
Vanadium nitrogenase can reduce CO2 to CO, CD4, C2D4, and C2D6. Its ability to reduce CO2 to C2 hydrocarbons adds another important reaction to the catalytic spectrum of the vanadium nitrogenase, that is, a reaction that involves CC coupling from CO2.
Insertion of Nitriles into Zirconocene-1-aza-1,3-diene Complexes: Chemoselective Synthesis of N-H and N-Substituted Pyrroles
Shasha Yu, Meijun Xiong, Xin Xie and Prof. Yuanhong Liu
Exercise control: N-H and N-substituted pyrroles can be prepared through the direct insertion of nitriles into zirconocene-1-aza-1,3-diene complexes and their subsequent acidic aqueous work-up. The outcome of the reaction depends on the relative stability and reactivity of the corresponding enamine–imine tautomers formed through the hydrolysis of the diazazirconacycles.
Anion Complexation and The Hofmeister Effect
Ryan S. Carnegie, Corinne L. D. Gibb and Prof. Bruce C. Gibb
The strength of association between the hydrophobic, concave binding site of a deep-cavity cavitand and the ClO4− ion is controlled by co-salts in a manner that follows the Hofmeister series. A competitive binding of the co-salt anion to the hydrophobic pocket and its counterion to the external carboxylate groups accounts for the observed changes in ClO4− affinity.
Fragment-Based Drug Discovery
Exploring Weak Ligand–Protein Interactions by Long-Lived NMR States : Improved Contrast in Fragment-Based Drug Screening
Roberto Buratto, Daniele Mammoli, Dr. Elisabetta Chiarparin, Dr. Glyn Williams and Prof. Geoffrey Bodenhausen
Ligands with an affinity for selected proteins can be screened very effectively by exploiting long-lived states (LLS) in NMR spectroscopy. This approach allows ligands with a wide range of affinities (10 nM<KD<12 mM) to be characterized. The LLS method was used to measure the dissociation constants of fragments that bind weakly to the ATP binding domain of heat shock protein Hsp90, a therapeutic target for cancer treatment.
An Organotrifluoroborate for Broadly Applicable One-Step 18F-Labeling
Zhibo Liu, Maral Pourghiasian, Mark Alex Radtke, Joseph Lau, Dr. Jinhe Pan, Gemma M. Dias, Dr. Donald Yapp, Dr. Kuo-Shyan Lin, Prof. Dr. Francois Bénard and Prof. Dr. David M. Perrin
Like a postage stamp that neither alters a letter’s weight nor changes its contents or destination, a new zwitterionic trifluoroborate radiosynthon transforms complex molecules into 18F-tracers that are labeled in a single aqueous-phase step in high yield and at high specific radioactivity without HPLC purification.
Forazoline A: Marine-Derived Polyketide with Antifungal In Vivo Efficacy
Thomas P. Wyche, Dr. Jeff S. Piotrowski, Dr. Yanpeng Hou, Doug Braun, Raamesh Deshpande, Sean McIlwain, Irene M. Ong, Chad L. Myers, Dr. Ilia A. Guzei, Dr. William M. Westler, Prof. Dr. David R. Andes and Prof. Dr. Tim S. Bugni
A bit of structure: A novel antifungal natural product, forazoline A, was isolated from Actinomadura sp. The structure of forazoline A was elucidated by a combination of NMR spectroscopy, molecular modeling, and synthetic modifications. The compound demonstrated in vivo efficacy in a mouse model of Candida albicans. A chemical genomics approach suggested that forazoline A works through a new mechanism of action.
Organic Dicarboxylate Negative Electrode Materials with Remarkably Small Strain for High-Voltage Bipolar Batteries
Dr. Nobuhiro Ogihara, Tomomi Yasuda, Yoshihiro Kishida, Dr. Tetsu Ohsuna, Kaito Miyamoto and Dr. Nobuko Ohba
Corridors of power: 2,6-Naphthalene dicarboxylate dilithium (Naph(COOLi)2), which has an organic–inorganic layered framework, shows reversible Li intercalation at a flat potential of 0.8 V. The layered framework is maintained during Li intercalation, and its volume change is only 0.33 %. An 8 V bipolar Naph(COOLi)2/LiNi0.5Mn1.5O4 cell with an Al current collector was constructed from only two cells connected in series.
Gas-Phase Preparation of Carbonic Acid and Its Monomethyl Ester
Dr. Hans Peter Reisenauer, M. Sc. J. Philipp Wagner and Prof. Dr. Peter R. Schreiner
The matrix-isolation IR spectrum of carbonic acid generated through gas-phase pyrolysis of Boc2O (Boc=tert-butoxycarbonyl) or (tBuO)2CO unequivocally shows that the long-claimed identity of the gas phase above its α-polymorph is not carbonic acid, but rather the monomethyl ester, which was analogously prepared from MeOC(O)OtBu and identified in the gas phase for the first time.
Enantioselective Synthesis of Piperidines through the Formation of Chiral Mixed Phosphoric Acid Acetals: Experimental and Theoretical Studies
Dr. Zhankui Sun, Grace A. Winschel, Prof. Dr. Paul M. Zimmerman and Prof. Dr. Pavel Nagorny
A rich seam: An enantioselective chiral phosphoric acid-catalyzed cyclization of unsaturated acetals has been utilized for the synthesis of functionalized chiral piperidines. The chiral enol ether products of these cyclizations undergo subsequent in situ enantioenrichment. A new computational method was utilized to elucidate the mechanism and stereoselectivity of this transformation. Cbz=benzyloxycarbonyl; S=resolution.
In Vivo Residue-Specific Dopa-Incorporated Engineered Mussel Bioglue with Enhanced Adhesion and Water Resistance
Byeongseon Yang, Dr. Niraikulam Ayyadurai, Prof. Hyungdon Yun, Prof. Yoo Seong Choi, Dr. Byeong Hee Hwang, Jun Huang, Dr. Qingye Lu, Prof. Hongbo Zeng and Prof. Hyung Joon Cha
Engineered mussel glue with a very high 3,4-dihydroxyphenylalanine (Dopa) content close to that of natural protein was created through in vivo residue-specific Dopa incorporation method in Escherichia coli. This bioglue exhibited strong adhesion and water-resistance, which shows great potential in underwater applications.
Engineering Catalyst Microenvironments for Metal-Catalyzed Hydrogenation of Biologically Derived Platform Chemicals
Thomas J. Schwartz, Robert L. Johnson, Javier Cardenas, Dr. Adam Okerlund, Prof. Nancy A. Da Silva, Prof. Klaus Schmidt-Rohr and Prof. James A. Dumesic
The surface properties of supported metal hydrogenation catalysts are modified by the formation of microenvironments inside the catalyst pores and surrounding the metal nanoparticles. These microenvironments are derived from poly(vinyl alcohol) (PVA), and they are used to mitigate catalyst deactivation that is due to biogenic impurities.
The optimally performing Fischer–Tropsch catalyst
Ivo A. W. Filot, Prof. Dr. Rutger A. van Santen and Prof. Dr. Emiel J. M. Hensen
State-of-the-art quantum-chemical reaction data were used in a microkinetics simulations study to elucidate the different fundamental kinetic regimes underlying Fischer–Tropsch activity and selectivity. Based on the nature of the rate-controlling steps, three regimes were identified: I) monomer formation, II) chain-growth termination, and III) water formation.
Formic Acid Dehydrogenation
Hydrogen from Formic Acid through Its Selective Disproportionation over Sodium Germanate—A Non-Transition-Metal Catalysis System
Dr. Ruth I. J. Amos, Dr. Falk Heinroth, Dr. Bun Chan, Sisi Zheng, Prof. Brian S. Haynes, Prof. Christopher J. Easton, Prof. Anthony F. Masters, Prof. Leo Radom and Prof. Thomas Maschmeyer
From models to reality: A robust catalyst for the selective dehydrogenation of formic acid to liberate hydrogen gas has been designed computationally, and also demonstrated experimentally. This catalyst represents an important step towards the use of renewable formic acid as a hydrogen-storage and transport vector in fuel and energy applications.
Anion–π and Cation–π Interactions on the Same Surface
Dr. Kaori Fujisawa, Dr. César Beuchat, Marie Humbert-Droz, Dr. Adam Wilson, Prof. Tomasz A. Wesolowski, Dr. Jiri Mareda, Dr. Naomi Sakai and Prof. Stefan Matile
It takes two to tango: Theoretical and experimental evidence shows that anion–π and cation–π interactions can occur simultaneously on the same aromatic surface. The resulting ion pair–π interactions shift the absorption of push–pull chromophores to the red.
Hot-Electron-Transfer Enhancement for the Efficient Energy Conversion of Visible Light
Sungju Yu, Yong Hwa Kim, Su Young Lee, Hyeon Don Song and Prof. Jongheop Yi
A core–shell nanostructure with three distinct components enables the efficient production of H2 from water and significant electron harvesting under visible-light irradiation because of enhanced hot-electron injection, the formation of a Schottky junction, and high-performance electron filtering. The electron transfer pathway is elucidated through steady-state and time-resolved photoluminescence spectroscopy.
Super-Resolution Imaging of Plasma Membrane Glycans
Sebastian Letschert, Dr. Antonia Göhler, Christian Franke, Nadja Bertleff-Zieschang, Elisabeth Memmel, Priv.-Doz. Dr. Sören Doose, Prof. Dr. Jürgen Seibel and Prof. Dr. Markus Sauer
Glycan spotting: Click chemistry and super-resolution imaging was used to visualize and quantify ManNAc-, GalNAc-, and O-GlcNAc-modified glycans in the plasma membrane of mammalian cells with single-molecule sensitivity (see image). The data demonstrate that a single cell may easily contain more than ten million glycans, which are homogeneously distributed and do not form clusters or nanodomains.
Ruthenium Pincer Complexes
Direct Catalytic Olefination of Alcohols with Sulfones
Dr. Dipankar Srimani, Dr. Gregory Leitus, Yehoshoa Ben-David and Prof. Dr. David Milstein
The one-step olefination of alcohols with sulfones for the direct synthesis of terminal and internal olefins is catalyzed by ruthenium pincer complexes. Furthermore, performing the reaction with dimethyl sulfone under mild hydrogen pressure provides a one-step method for the replacement of alcohol hydroxy groups by methyl groups.
Dialdehydes Lead to Exceptionally Fast Bioconjugations at Neutral pH by Virtue of a Cyclic Intermediate
Pascal Schmidt, Dr. Linna Zhou, Kiril Tishinov, Kaspar Zimmermann and Prof. Dr. Dennis Gillingham
For aldehydes, 1+1=500: Dialdehydes react with O-alkylhydroxylamines at rates of 500 M−1 s−1 at neutral pH values in the absence of catalysts. The key to these conjugations is an unusually stable cyclic intermediate, which ultimately undergoes dehydration to yield an oxime. The application of this method in bioconjugations and a mechanistic interpretation are outlined.
Controlling Selectivity in the Chlorine Evolution Reaction over RuO2-Based Catalysts
Kai S. Exner, Josef Anton, Timo Jacob and Herbert Over
Being selective: The selectivity in the industrially important Chlor-Alkali process has been elucidated on the microscopic level through a combination of DFT calculations and volcano plots. A single layer of TiO2(110) grown on RuO2(110) increases the selectivity between the chlorine and oxygen evolution reactions (CER and OER, respectively) by several orders of magnitude, while keeping the high activity for CER practically constant.
Aldehyde-Assisted Ruthenium(II)-Catalyzed CH Oxygenations
M. Sc. Fanzhi Yang, Karsten Rauch, M. Sc. Katharina Kettelhoit and Prof. Dr. Lutz Ackermann
The weakest link: Challenging aryl CH oxygenations with very weakly coordinating aldehydes proceed chemoselectively in the presence of versatile ruthenium(II) catalysts under mild reaction conditions. This transformation features an ample substrate scope and excellent positional selectivity.
Unexpected Synergy between Magnetic Iron Chains and Stacked B6 Rings in Nb6Fe1−xIr6+xB8
Dipl.-Chem. Mohammed Mbarki, M.Sc. Rachid St. Touzani and Priv.-Doz. Dr. Boniface P. T. Fokwa
A mutual dependency between ferromagnetic iron chains and stacked B6 rings (see picture) is found in the new ferromagnetic material, Nb6Fe1−xIr6+xB8 (TC=350 K) by combining experiment and density functional theory (DFT). The strong magnetic Fe–Fe interactions found in the iron chains induce an unexpected strengthening of the B–B interactions in the B6 rings.
Vanadium-Catalyzed Solvent-Free Synthesis of Quaternary α-Trifluoromethyl Nitriles by Electrophilic Trifluoromethylation
Natalja Früh and Prof. Dr. Antonio Togni
Not only copper! Oxovanadium(IV) complexes catalyze the trifluoromethylation of silyl ketene imines with hypervalent iodine reagents to form quaternary α-trifluoromethyl nitriles under solvent-free conditions. The products, formed in up to 93 % yield, may be further transformed into useful synthetic building blocks for organofluorine chemistry.
Ruthenium-Catalyzed Reductive Methylation of Imines Using Carbon Dioxide and Molecular Hydrogen
Dr. Kassem Beydoun, Ghazi Ghattas, Katharina Thenert, Prof. Dr. Jürgen Klankermayer and Prof. Dr. Walter Leitner
Tertiary N-methyl amines were obtained in good to excellent yields through the reductive methylation of imines (used as such or formed in situ from amines and aldehydes, see scheme). Apart from the well-defined [Ru(triphos)(tmm)] catalyst, CO2 was used as C1 source, and H2 as reducing agent. This method enabled the preparation of the antifungal agent butenafine in one step with no apparent waste, thus increasing the atom efficiency of its synthesis.
Phosphonated Near-Infrared Fluorophores for Biomedical Imaging of Bone
Dr. Hoon Hyun, Dr. Hideyuki Wada, Dr. Kai Bao, Dr. Julien Gravier, Dr. Yogesh Yadav, Dr. Matt Laramie, Dr. Maged Henary, Dr. John V. Frangioni and Dr. Hak Soo Choi
Bifunctional molecules with high-affinity binding to bone minerals as well as bright near-infrared fluorescence were obtained by attaching low-affinity pendant groups to the non-delocalized backbone of polymethines. These agents enable the noninvasive assessment of bone development over the course of weeks in living animals.
Planet–Satellite Nanostructures Made To Order by RAFT Star Polymers
Christian Rossner and Prof. Dr. Philipp Vana
Small world: Gold nanoparticles decorated with RAFT star polymers of different molecular weights can be used as scaffolds for the attachment of functional units at defined distances from the central core. This approach can result in planet–satellite nanostructures.
Harvesting Solar Light with Crystalline Carbon Nitrides for Efficient Photocatalytic Hydrogen Evolution
Dr. Manas K. Bhunia, Dr. Kazuo Yamauchi and Prof. Kazuhiro Takanabe
Trying out triazine: Crystalline carbon nitrides are synthesized by employing supramolecular aggregation and ionic melt polycondensation. The triazine-based carbon nitride exhibits the excellent hydrogen evolution reaction rate at visible light and apparent quantum yield reaches approximately 7 % at 420 nm.
Oxygen Reduction Reaction
Oxygen Reduction Reaction in a Droplet on Graphite: Direct Evidence that the Edge is More Active than the Basal Plane
Anli Shen, Yuqin Zou, Prof. Qiang Wang, Prof. Robert A. W. Dryfe, Prof. Xiaobing Huang, Shuo Dou, Prof. Liming Dai and Prof. Shuangyin Wang
On the cutting edge: To study the oxygen reduction reaction (ORR), an air-saturated electrolyte solution droplet with a diameter of approximately 15 μm was deposited at a specified position on the edge (see picture) or on the basal plane of highly oriented pyrolytic graphite. Electrochemical measurements suggest that the edge sites are catalytically more active than basal-plane sites towards the ORR.
One-Pot Enzymatic Synthesis of Merochlorin A and B
Dr. Robin Teufel, Dr. Leonard Kaysser, Matthew T. Villaume, Dr. Stefan Diethelm, Mary K. Carbullido, Prof. Dr. Phil S. Baran and Prof. Dr. Bradley S. Moore
Assembly line: The biosynthetic pathway to merochlorins A and B was fully reconstituted in vitro and involves only four enzymes. The assembly route starts from the common metabolites dimethylallyl diphosphate, geranyl diphosphate, and malonyl CoA, which are transformed into an unusual polyketide-terpene hybrid intermediate. Oxidative chlorination and terpene cyclization complete the remarkably short pathway to the merochlorins.
Metal-Free Hydrogenation Catalyzed by an Air-Stable Borane: Use of Solvent as a Frustrated Lewis Base
Daniel J. Scott, Dr. Matthew J. Fuchter and Dr. Andrew E. Ashley
Reduced frustration: THF solutions of the boranes B(C6Cl5)x(C6F5)3−x (x=0–3) activate H2 and effect catalytic hydrogenation of unsaturated substrates through a mechanism in which the solvent acts as a “frustrated” Lewis base. In particular, weakly basic substrates, such as N-tosyl imines, and pyrrole and furan derivatives (a new substrate family for frustrated Lewis pair (FLP) hydrogenations), are reduced under relatively mild conditions using air-stable B(C6Cl5)(C6F5)2.
A New Class of Organocatalysts: Sulfenate Anions
Mengnan Zhang, Tiezheng Jia, Haolin Yin, Patrick J. Carroll, Prof. Eric J. Schelter and Prof. Patrick J. Walsh
Sulfenates take center stage: Sulfenate anions are known as highly reactive species in the organic arena. Now they premiere as organocatalysts: A sulfoxide/sulfenate (1–10 mol %) promotes the transformation of benzyl halides into trans-stilbenes under basic conditions (up to 99 % yield). CPME=cyclopentyl methyl ether.
Mononuclear and Terminal Zirconium and Hafnium Methylidenes
Dr. Masahiro Kamitani, Balazs Pinter, Dr. Chun-Hsing Chen, Dr. Maren Pink and Prof. Dr. Daniel J. Mindiola
The photolysis of zirconium or hafnium complexes with one aryloxide and two methyl ligands induces α-hydrogen abstraction and results in the formation of mononuclear complexes with terminal methylidene ligands. These unique systems have been fully characterized, including the determination of the solid-state structure in the case of the zirconium complex.
N-Heterocyclic Carbene Catalyzed Formal [3+2] Annulation Reaction of Enals: An Efficient Enantioselective Access to Spiro-Heterocycles
Dr. Chang Guo, Michael Schedler, Constantin G. Daniliuc and Prof. Dr. Frank Glorius
Ring, ring: A highly enantioselective formal [3+2] annulation of α,β-unsaturated aldehydes with azaaurones or aurone is catalyzed by an N-heterocyclic carbene (NHC) and generates spiroheterocycles. The protocol represents a unique NHC activation-based approach to access spiro-heterocyclic derivatives bearing a quaternary stereogenic center with high optical purity.
Visualizing an Ultra-Weak Protein–Protein Interaction in Phosphorylation Signaling
Qiong Xing, Peng Huang, Ju Yang, Jian-Qiang Sun, Dr. Zhou Gong, Dr. Xu Dong, Dr. Da-Chuan Guo, Shao-Min Chen, Yu-Hong Yang, Yan Wang, Prof. Ming-Hui Yang, Dr. Ming Yi, Prof. Yi-Ming Ding, Prof. Mai-Li Liu, Prof. Wei-Ping Zhang and Prof. Chun Tang
Phosphorylation signaling takes place between two bacterial enzymes EI and EIIAGlc that has a binding affinity of only 25 mM (see picture). The structure of the ultra-weak fleeting complex was determined to atomic resolution by novel paramagnetic NMR technique, and it shows that electrostatic repulsion largely accounts for the low affinity between the two proteins.
Temporary Protecting Groups
Carbon Dioxide as a Protecting Group: Highly Efficient and Selective Catalytic Access to Cyclic cis-Diol Scaffolds
Victor Laserna, Dr. Giulia Fiorani, Dr. Christopher J. Whiteoak, Dr. Eddy Martin, Eduardo Escudero-Adán and Prof. Dr. Arjan W. Kleij
Protective Carbon: Aminotriphenolate complexes of FeIII and AlIII are highly efficient and selective catalysts for the conversion of functional (multi)cyclic oxiranes into the corresponding cis carbonates. Basic hydrolysis of the latter provides a series of useful cyclic cis-diol scaffolds in high yield. In this process, CO2 acts as both a temporary protecting group and an oxygen donor.
Iron-Catalyzed C(sp2)H Alkylation of Carboxamides with Primary Electrophiles
Brendan M. Monks, Erin R. Fruchey and Prof. Silas P. Cook
The direct ortho alkylation of 8-aminoquinoline-based aryl amides was achieved with primary alkyl bromides in high yields in the presence of an iron catalyst, 1,2-bis(diphenylphosphino)ethane (dppe), and PhMgBr in 2-MeTHF.
Ultra-Low-Field NMR Relaxation and Diffusion Measurements Using an Optical Magnetometer
Paul J. Ganssle, Hyun D. Shin, Dr. Scott J. Seltzer, Dr. Vikram S. Bajaj, Dr. Micah P. Ledbetter, Prof. Dmitry Budker, Dr. Svenja Knappe, Dr. John Kitching and Prof. Alexander Pines
Portable NMR: NMR relaxometry and diffusometry can be highly effective in applications where high-resolution NMR spectroscopy is unnecessary or impractical, as is the case in the emerging field of portable chemical characterization. A proof-of-concept experiment is presented demonstrating the use of high-sensitivity optical magnetometers as detectors for ultra-low-field NMR relaxation and diffusion measurements.