Blog Archive

Αλέξανδρος Γ. Σφακιανάκης

Saturday, June 29, 2019

Synthesis of Indoles through Domino Reactions of 2‐Fluorotoluenes and Nitriles
Indoles galore: A remarkably easy synthesis of indoles is introduced. Simply combining 2‐fluorotoluenes, benzonitriles, base, and CsF followed by heating results in the formation of 2‐aryl indoles with diverse substitution patterns. Abstract Indoles are essential heterocycles in medicinal chemistry, and therefore, novel and efficient approaches to their synthesis are in high demand. Among indoles, 2‐aryl indoles have been described as privileged scaffolds. Advanced herein is a straightforward,...
Angewandte Chemie International Edition
1h
Gas‐Constructed Vesicles with Gas‐Mouldable Membrane Architectures
Integrating gas as a main building block into nanomaterial construction is a challenging mission that remains elusive. Here we report a gas‐constructed vesicular system formed by CO2 gas and frustrated Lewis pair (FLP). Two molecular triads bearing three bulky borane and phosphine groups are designed as trivalent disc‐like FLP monomers. CO2, as a gas cross‐linker, can drive a two‐dimensional polymerization of these two FLP monomers, leading to the generation of planar FLP networks and further transform...
Angewandte Chemie International Edition
1h
Dibenzoarsepins: Planarization of 8π‐Electron System in the Lowest Singlet Excited State
Dibenzo[b,f]arsepins, 3‐Me and 3‐Ph, possessing severely distorted cores as compared to other heteropin families, were synthesized. These derivatives exhibited dual photoluminescence in the green‐to‐red region (500~700 nm) and the near‐ultraviolet region (<380 nm), which could be attributed to the planarization of the arsepin cores in the lowest singlet excited (S1) states. The computational approach for the assessment of the aromatic indices revealed that 3‐Me and 3‐Ph show aromaticity (8π system)...
Angewandte Chemie International Edition
1h
Engineered peptide macrocycles can inhibit matrix metalloproteinases with high selectivity
Matrix metalloproteinases (MMPs) are zinc‐dependent endopeptidases at the intersection of health and disease due to their involvement in processes such as tissue repair and immunity as well as cancer and inflammation. Because of the high structural conservation in the catalytic domains and shallow substrate binding sites, selective, small‐molecule inhibitors of MMPs have remained elusive. In a tour‐de‐force peptide engineering approach combining phage display selections, rational design of enhanced...
Angewandte Chemie International Edition
1h
Stepwise Reduction of Azapentabenzocorannulene
Mono‐ and dianions of 2‐tert‐butyl‐3a2‐azapentabenzo[bc,ef,hi,kl,no]corannulene (1a) were synthesized by chemical reduction with sodium and cesium metals and crystallized as the corresponding salts in the presence of 18‐crown‐6 ether. X‐ray diffraction analysis of the sodium salt, [{Na+(18‐crown‐6)(THF)2}3{Na+(18‐crown‐6)(THF)}(1a2–)2], revealed the presence of a naked dianion. In contrast, the controlled reactions of 1a with Cs allowed the isolation of mono‐ and doubly‐reduced forms of 1a, both...
Angewandte Chemie International Edition
1h
Visible‐light Induced [4+2] Annulation of Thiophenes and Alkynes to Construct Benzene Rings
[4+2] Annulation represents an elegant and versatile synthetic protocol for the construction of benzene rings. Herein, a strategy for visible‐light induced [4+2] annulation of thiophenes and alkynes to afford benzene rings is presented. Under simple and mild conditions, the easy availability and structural diversity of thiophenes and alkynes permit the facile synthesis of multifarious substituted aromatic rings. Valuable drugs and amino acids are also well tolerated. Moreover, DFT calculations explain...
Angewandte Chemie International Edition
1h
N‐Heterocyclic Carbene/Copper Cooperatively Catalyzed Asymmetric Synthesis of Spirooxindoles
Highly enantioselective [3+3] and [3+4] annulations of isatin‐derived enals with ethynylethylene carbonates and ethynyl benzoxazinanones have been enabled by NHC/cooper cooperative catalysis, respectively, leading to a big library of spirooxindole derivatives in high structural diversity and enantioselectivity (up to 99% ee). Both reactions represent a nicely synergistic integration of NHC carbene and copper catalysis, in which each catalyst activates the substrates, respectively, and the chiral...
Angewandte Chemie International Edition
1h
Pentafluoro(aryl)‐λ6‐tellanes and Tetrafluoro(aryl)(trifluorometh‐yl)‐λ6‐tellanes: From SF5 to the TeF5 and TeF4CF3 Groups
The TeF5 group is significantly underexplored as a highly fluorinated substituent on an organic framework, despite it being a larger congener of the acclaimed SF5 group. In fact, only one aryl‐TeF5 compound (phenyl‐TeF5) has been reported in the literature to date, synthesized using XeF2 – a testament to a clear lack of synthetic accessibility. Herein, our recently developed mild TCICA/KF approach to oxidative fluorination addresses this problem by providing an affordable and scalable alternative...
Angewandte Chemie International Edition
1h
Ethynylphosphonamidates for the rapid and cysteine selective generation of efficacious Antibody‐Drug‐Conjugates
Requirements for novel bioconjugation reactions for the synthesis of Antibody‐Drug‐Conjugates (ADCs) are exceptionally high, since conjugation selectivity as well as stability and hydrophobicity of linkers and payloads drastically influence the performance and safety profile of the final product. Herein we describe Cys‐selective ethynylphosphonamidates as new reagents for the rapid generation of efficacious ADCs from native non‐engineered monoclonal antibodies, applying a simple one‐pot reduction...
Angewandte Chemie International Edition
1h
Dual‐Controlled Macroscopic Motions in a Supramolecular Hierarchical Assembly of Motor Amphiphiles
Unidirectionally aligned responsive supramolecular hierarchical assemblies have much potential in biomedical materials and soft actuators. Macroscopic motor amphiphile strings, decorated with iron nanoparticles, provide fast response photoactuation and magnet induced movements that allow a systematic cargo transport process. Abstract Three‐dimensional unidirectionally aligned and responsive supramolecular hierarchical assemblies have much potential in adaptive materials for biomedical and soft...
Angewandte Chemie International Edition
1h
A Regio‐ and Stereodivergent Synthesis of Homoallylic Amines by a One‐Pot Cooperative‐Catalysis‐Based Allylic Alkylation/Hofmann Rearrangement Strategy
Cooperation then amination: A unified one‐pot experimental procedure enables a versatile regio‐ and stereodivergent synthesis of homoallylic amines. Critical to the successful development of this method was the recognition that initial catalyzed C−C bond formation controls all aspects of regio‐ and stereoselectivity. Thereafter, in situ amination/Hofmann rearrangement results in stereospecific C−N bond formation. Abstract Herein, we report a modular synthetic route to linear and branched homoallylic...
Angewandte Chemie International Edition
1h
Resolving the Unpaired‐Electron Orbital Distribution in a Stable Organic Radical by Kondo Resonance Mapping
The adsorption geometry and the electronic structure of a Blatter radical derivative on a gold surface were investigated by atomic force/scanning tunneling microscopy. The unpaired‐electron orbital was probed with Ångström resolution by mapping the spatial distribution of the Kondo resonance. Abstract The adsorption geometry and the electronic structure of a Blatter radical derivative on a gold surface were investigated by a combination of high‐resolution noncontact atomic force microscopy...
Angewandte Chemie International Edition
1h
Copper‐Complex‐Catalyzed Asymmetric Aerobic Oxidative Cross‐Coupling of 2‐Naphthols: Enantioselective Synthesis of 3,3′‐Substituted C1‐Symmetric BINOLs
Enabler: An asymmetric aerobic oxidative cross‐coupling of 2‐naphthols, enabled by a novel Cu/SPDO system, generates a series of chiral C1‐symmetric BINOLs bearing 3,3′‐substituents. This method features high enantioselectivity, good chemoselectivity, and a broad substrate scope. The prepared C1‐symmetric BINOL organocatalysts gave better enantioselectivity than the previously reported catalyst for the asymmetric α‐alkylation of amino esters. Abstract A novel chiral 1,5‐N,N‐bidentate ligand...
Angewandte Chemie International Edition
1h
The Interplay between Structure and Product Selectivity of CO2 Hydrogenation
The correlation of Co3O4 catalysts having different crystallographic surfaces with reducibility and the formation energy of oxygen vacancies is described. Distinct product selectivity of CO2 hydrogenation is observed. The key step (CH3−O* bond breaking), which affects C1 product distribution, was identified by in situ DRIFTS and DFT, suggesting that oxygen vacancies can promote the CH3−O* bond breaking. Abstract Identification of the active structure under reaction conditions is of great importance...
Angewandte Chemie International Edition
1h
Inhibition of HER2‐Positive Breast Cancer Growth by Blocking the HER2 Signaling Pathway with HER2‐Glycan‐Imprinted Nanoparticles
Molecularly imprinted polymers (nanoMIPs) are used to inhibit the growth of HER2‐positive breast cancer. NanoMIPs, imprinted using HER2 glycans, can bind to these glycans, preventing HER2 heterodimerization. This blocks HER2‐dependent signaling pathways and leads to the inhibition of HER2‐positive breast cancer growth. Abstract Blocking the HER2 signaling pathway has been an effective strategy in the treatment of HER2‐positive breast cancer. It mainly relies on the use of monoclonal antibodies...
Angewandte Chemie International Edition
1h
Duplex‐Guided Refolding into Novel G‐Quadruplex (3+1) Hybrid Conformations
A parallel G‐quadruplex was guided into a novel (3+1) hybrid topology with a lateral–propeller–propeller loop architecture and two different syn/anti patterns within the G‐core by introducing additional Watson–Crick hydrogen bonding interactions between complementary 5′‐ and 3′‐flanking sequences. Abstract The oligomer d(GCGTG3TCAG3TG3TG3ACGC) with short complementary flanking sequences at the 5′‐ and 3′‐ends was shown to fold into three different DNA G‐quadruplex species. In contrast, a corresponding...
Angewandte Chemie International Edition
1h
Oxidative Coupling of Terminal Rhenium Pnictide Complexes
A radical coupling: The use of a hemilabile ligand that facilitates decarbonylation upon linkage isomerism enabled the synthesis and isolation of terminal rhenium phosphide and arsenide complexes from pnictaethynolate precursors. One‐electron oxidation of the pnictide complexes resulted in intermolecular Pn−Pn coupling, giving side‐on bound P2 and As2 species. Abstract The isolation of rhenium(V) complexes with terminal phosphide and arsenide ligands was achieved upon decarbonylation of rhenium(III)...
Angewandte Chemie International Edition
1h
Nickel‐Catalyzed Arylboration of Alkenylarenes: Synthesis of Boron‐Substituted Quaternary Carbons and Regiodivergent Reactions
Boron‐substituted quaternary carbon or diarylquaternary carbon centers are constructed by arylboration of highly substituted alkenylarenes. A wide range of alkenes and arylbromides can participate in this reaction. In addition, a solvent dependent regiodivergent arylboration of 1,2‐disubstituted alkenylarenes is presented, thus greatly increasing the scope of products that can be accessed. Abstract A method for the construction of boron‐substituted quaternary carbons or diarylquaternary carbons...
Angewandte Chemie International Edition
1h
Recent Advances on Electrochemical Biosensing Strategies toward Universal Point‐of‐Care Systems
Making good biosense: Recent cutting‐edge research on electrochemical biosensing strategies are described. These developments resolved critical challenges regarding the application of electrochemical biosensors to practical point‐of‐care systems, such as rapid readout, simple biosensor fabrication method, ultra‐high detection sensitivity, direct analysis in a complex biological matrix, and multiplexed target analysis. Abstract A number of very recently developed electrochemical biosensing strategies...
Angewandte Chemie International Edition
1h
A Molecular Cobalt Hydrogen Evolution Catalyst Showing High Activity and Outstanding Tolerance to CO and O2
Highly tolerant: A cobalt(II) complex of a pentadentate ligand can efficiently electrocatalyze hydrogen evolution in an aqueous phosphate buffer at pH 7.0, affording a fast catalytic rate of 2210 s−1. This complex has a high tolerance to both CO and air, displaying over 90 % retention of its catalytic activity under CO‐ and air‐saturated conditions. Abstract There is a demand to develop molecular catalysts promoting the hydrogen evolution reaction (HER) with a high catalytic rate and a high...
Angewandte Chemie International Edition
1h
Formation of Neutral Peptide Aggregates as Studied by Mass‐Selective IR Action Spectroscopy
Growing aggregates on the fly: The largest isolated neutral peptide aggregates were grown by using laser desorption molecular beam techniques. Infrared action spectroscopy was employed to visualize their predominantly parallel β sheet type structures. Abstract The spontaneous aggregation of proteins and peptides is widely studied owing to its relation to neurodegenerative diseases. To understand the underlying principles of peptide aggregation, elucidation of structure and structural changes...
Angewandte Chemie International Edition
1h
Superionic Conduction over a Wide Temperature Range in a Metal–Organic Framework Impregnated with Ionic Liquids
Super IL‐MOF: An unprecedented solid‐state superionic conductor was obtained by incorporating an ionic liquid (IL) into a mesoporous metal–organic framework (MOF). Because ILs occupying the core of mesopores behave as bulk, the hybrid shows the highest room‐temperature conductivity (4.4×10−3 S cm−1) among the IL‐incorporated MOF hybrids reported to date. Abstract Most molecules in confined spaces show markedly different behaviors from those in the bulk. Large pores are composed of two regions:...
Angewandte Chemie International Edition
1h
Selective Aerobic Oxygenation of Tertiary Allylic Alcohols with Molecular Oxygen
Solvent sourcing: A highly chemoselective copper‐catalyzed epoxidation and semipinacol rearrangement of tertiary allylic alcohols with molecular oxygen has been developed. 1,4‐Dioxane was used as the solvent as well as an oxygen‐atom source, thereby avoiding the requirement of additional sacrificial agents. Abstract Aerobic epoxidation of tertiary allylic alcohols remains a significant challenge. Reported here is an efficient and highly chemoselective copper‐catalyzed epoxidation and semipinacol...
Angewandte Chemie International Edition
1h
An Antitumor Bis(N‐Heterocyclic Carbene)Platinum(II) Complex That Engages Asparagine Synthetase as an Anticancer Target
The platinum complex [(bis‐NHC)Pt(bt)]PF6 (1 a) exhibits anticancer activity towards a wide range of cancer cells and displays significant in vivo tumor growth inhibition in mice. Asparagine synthetase (ASNS) was identified as a molecular target of 1 a. Binding studies suggest that [(bis‐NHC)Pt]2+ forms adducts with thiols and targets the active‐site N‐terminal cysteine of ASNS. Abstract New anticancer platinum(II) compounds with distinctive modes of action are appealing alternatives to combat...
Angewandte Chemie International Edition
1h
CO2 Fixation and Catalytic Reduction by a Neutral Aluminum Double Bond
CO2 fixation by an aluminum–aluminum double bond promotes catalytic and stoichiometric reduction under mild conditions. Abstract CO2 fixation and reduction to value‐added products is of utmost importance in the battle against rising CO2 levels in the Earth's atmosphere. An organoaluminum complex containing a formal aluminum double bond (dialumene), and thus an alkene equivalent, was used for the fixation and reduction of CO2. The CO2 fixation complex undergoes further reactivity in either the...
Angewandte Chemie International Edition
1h
Ligand‐Directed Template Assembly for the Construction of Gigantic Molybdenum Blue Wheels
Gigantic Mo Blue clusters with ligand directed template⊂host architectures are constructed via anion‐templated self‐assembly with l‐ornithine as structure‐directing agent. Based on the structural relationship between encapsulated templates of {Mo8}, {Mo17} and {Mo36}, a pathway of the structural evolution of templates can be proposed. Abstract Template‐mediated synthesis is a powerful approach to build a variety of functional materials and complex supramolecular systems. However, the systematic...
Angewandte Chemie International Edition
1h

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