Spotlights on our sister journals: Angew. Chem. Int. Ed. 42/2018.
Authors: PMID: 30300946 [PubMed - in process] (Source: Angewandte Chemie)
Source: Angewandte Chemie - October 11, 2018 Category: Chemistry Tags: Angew Chem Int Ed Engl Source Type: research
A Ligand Enabled Palladium Catalyzed Highly para-Selective Difluoromethylation of Aromatic Ketones.
Abstract A practical and highly para-selective C-H difluoromethylation of aromatic ketones has been developed by employing tetrakis(triphenylphosphine)palladium(0) as the catalyst and triphenylphosphine as the ligand. In addition to general aromatic ketones, this transformation was compatible with bioactive compounds and well-known drugs, such as oxybenzone, ketoprofen, zaltoprofen, and propafenone. Moreover, the mechanistic study revealed that the palladium complex coordinated with the carbonyl group to affect the highly para-selective difluoromethylation reaction. PMID: 30299562 [PubMed - as supplied by pub...
Source: Angewandte Chemie - October 9, 2018 Category: Chemistry Authors: Tu G, Yuan C, Li Y, Zhang J, Zhao Y Tags: Angew Chem Int Ed Engl Source Type: research
Facile Activation of Homoatomic σ Bonds in White Phosphorus and Diborane by a Diboraallene.
Facile Activation of Homoatomic σ Bonds in White Phosphorus and Diborane by a Diboraallene. Angew Chem Int Ed Engl. 2018 Oct 09;: Authors: Lu W, Xu K, Li Y, Hirao H, Kinjo R Abstract Metal-free activation of homoatomic E-E σ bonds (E = P, B) of white phosphorus (P4) and bis(catecholato)diboron (B2cat2) with a 1,2-diboraallene (1) is reported. The 1:1 and 1:2 reactions of P4 with (1) afford BnP4 cages (2: n = 2, 3: n = 4),whereas a stoichiometric mixture of (1) and B2cat2 undergoes homonuclear catenation via the addition of the B-B σ bond of B2cat2 across the B=B double bond of (1) (i...
Source: Angewandte Chemie - October 9, 2018 Category: Chemistry Authors: Lu W, Xu K, Li Y, Hirao H, Kinjo R Tags: Angew Chem Int Ed Engl Source Type: research
"On water" Surface-initiated Polymerization of Hydrophobic Monomers.
We present the "on water" surface-initiated Cu-mediated controlled radical polymerization ("on water" SI-CuCRP) that convert hydrophobic monomers in aqueous reaction medium to polymer brushes at unparalleled speed and efficiency. The method allows the facile conversion of a variety of common monomers under most simple reaction conditions and with minimal (a few µL) monomer amounts to thick and homogeneous polymer brushes. The highly living character of the "on water" SI-CuCRP allowed the preparation of decablock (homo)polymer brushes and opens the pathway to sequentially controlled polym...
Source: Angewandte Chemie - October 9, 2018 Category: Chemistry Authors: Zhang T, Che Y, Du Y, Ihsan A, Marschelke C, Jordan R Tags: Angew Chem Int Ed Engl Source Type: research
Light-Induced Gold-Catalyzed Hiyama Arylation: A Coupling Access to Biarylboronates.
ASK Abstract Organoboron compounds are versatile synthetic building blocks. We herein report a new strategy, a photochemical gold-catalyzed chemo-selective Hiyama arylation of B,Si bimetallic reagents with diazonium salts, which is orthogonal to common strategies and therefore a unique tool for synthesis of valuable biarylboronates. With this new methodology a wide array of diversely functionalized sp2- and sp3-hybridized biarylboronates were obtained. Notably, the synergism of gold catalysis with copper catalysis or palladium catalysis, allows for one-pot iterative C-X (heteroatom) and C-C couplings for the rapid...
Source: Angewandte Chemie - October 9, 2018 Category: Chemistry Authors: Xie J, Sekine K, Witzel S, Krämer P, Rudolph M, Rominger F, Hashmi ASK Tags: Angew Chem Int Ed Engl Source Type: research
Enantioselective Access to S-Chiral 1,2-Benzothiazines by CpxRh(III) Catalyzed C-H Functionalization of Sulfoximines.
Abstract Sulfoximines with stereogenic sulfur atoms are attractive structural motifs in drug discovery. A direct catalytic enantioselective method accessing S-chiral 1,2-benzothiazines from readily accessible diarylsulfoximines is presented. Rhodium(III) complexes equipped with chiral cyclopentadienyl ligands and paired with suitable carboxylic acid additives engage in an enantiodetermining C-H activation directed by the sulfoximine group. Subsequent trapping of the rhodacycle by a broad range of diazoketones gives access to S chiral 1,2-benzothiazines with synthetically highly attractive substitution patterns in ...
Source: Angewandte Chemie - October 9, 2018 Category: Chemistry Authors: Cramer N, Sun Y Tags: Angew Chem Int Ed Engl Source Type: research
Highly diastereo- and enantioselective synthesis of nitrile-substituted cyclopropanes via myoglobin-mediated carbene transfer catalysis.
Abstract A chemobiocatalytic strategy for the highly stereoselective synthesis of nitrile-substituted cyclopropanes is reported. The present approach relies on an asymmetric olefin cyclopropanation reaction catalyzed by an engineered myoglobin in the presence of ex situ generated diazoacetonitrile within a compartmentalized reaction system. This method enabled the efficient transformation of a broad range of olefin substrates at the preparative scale with up to 99.9% de and ee and up to 5,600 turnovers. The enzymatic product could be further diversified to furnish a variety of functionalized chiral cyclopropanes. ...
Source: Angewandte Chemie - October 9, 2018 Category: Chemistry Authors: Fasan R, Chandgude AL Tags: Angew Chem Int Ed Engl Source Type: research
Radical-mediated thiol-ene strategy for photoactivation of thiol-containing drugs in cancer cells.
rnardes GJL Abstract Photo-activated drugs provide an opportunity to improve efficacy alongside reducing side-effects in the treatment of severe diseases, such as cancer. Herein, we describe a photoactivation decaging method of isobutylene-caged thiols through a UV-initiated thiol-ene reaction. The method was demonstrated with an isobutylene-caged cysteine, cyclic disulfide-peptide and thiol-containing drug, all of which were rapidly and efficiently released under mild UV irradiation in the presence of thiol sources and a photoinitiator. Importantly, we show that the activity of histone deacetylase inhibitor Larga...
Source: Angewandte Chemie - October 9, 2018 Category: Chemistry Authors: Sun S, Oliveira B, Jiménez-Osés G, Bernardes GJL Tags: Angew Chem Int Ed Engl Source Type: research
Catalytic Enantioselective Aldol Reaction of Unprotected Carboxylic Acids under Phosphine Oxide Catalysis.
Abstract The first catalytic enantioselective aldol reaction of various unprotected carboxylic acids is described. In the presence of a biaryl-bisphosphine oxide as a chiral Lewis base catalyst, carboxylic acids are activated with silicon tetrachloride to form the corresponding bis(trichlorosilyl)enediolates in situ, that subsequently undergo the aldol reaction with an aldehyde or a ketone to produce β-hydroxycarboxylic acids in high enantioselectivity of up to 92% ee. PMID: 30298544 [PubMed - as supplied by publisher] (Source: Angewandte Chemie)
Source: Angewandte Chemie - October 8, 2018 Category: Chemistry Authors: Kotani S, Yoshiwara Y, Ogasawara M, Sugiura M, Nakajima M Tags: Angew Chem Int Ed Engl Source Type: research
Vertical Step-Growth Polymerization Driven by Electrochemical Stimuli from Electrode.
We presented here that vertical step-growth polymerization of monomer A-B via individual A-A or B-B coupling driven by electrochemically switching positive and negative bias on self-assembled A or B electrode. In particular, monomer is Ru(II)(bda)AB (bda = 2,2'-bipyridine-6,6'-dicarboxylate), where A and B are pyridines with pendant carbazolyl and vinyl, which can be dimerized at oxidative potential (ca. 1.0 V vs. Ag/Ag+) and reductive potential (ca. -1.8 V), respectively. Self-assembled monolayers on ITO glass are Ru(II)(bda)PA or Ru(II)(bda)PB (P = pyridine with pendant phosphonic acid). This well-controlled polymerizati...
Source: Angewandte Chemie - October 8, 2018 Category: Chemistry Authors: Zhang J, Du J, Wang J, Wang Y, Wei C, Li M Tags: Angew Chem Int Ed Engl Source Type: research
Terraced and Smooth Gradient Polymer Brushes via a Polymer-Single-Crystal-Assisted-Grafting-To Method.
In this study, we present a bottom-up method to synthesize gradient polymer brushes with predesigned and precisely controlled grafting density gradient and brush pattern. A polymer-single-crystal-assisted-grafting-to (PSCAGT) method was employed where end-functionalized polymers were grown into two-dimensional polymer single crystals. The latter were chemically coupled to a solid substrate to form well-defined polymer brushes. To tune the grafting density, end-dissimilar polymers were used to co-crystallize into one single crystal. Programmed single crystal growth was introduced to synthesize brushes with two different gra...
Source: Angewandte Chemie - October 8, 2018 Category: Chemistry Authors: Li CY, Mei S Tags: Angew Chem Int Ed Engl Source Type: research
Diversity-Oriented Construction and Interconversion of Multicavity Supermacrocycles for Cooperative Anion- π Binding.
Diversity-Oriented Construction and Interconversion of Multicavity Supermacrocycles for Cooperative Anion-π Binding. Angew Chem Int Ed Engl. 2018 Oct 08;: Authors: Luo J, Ao YF, Wang QQ, Wang DX Abstract A one-pot strategy for diverse construction of a series of supermacrocycles was realized using rationally designed macrocyclic precursors 3a-e. The base was found to have significant control over not only the size distribution but also the structure of the supermacrocycles formed. While the use of less CsF ( 8.0 eq.) resulted in structurally reorganized supermacrocyles B8-B10 possessing oxacalix...
Source: Angewandte Chemie - October 8, 2018 Category: Chemistry Authors: Luo J, Ao YF, Wang QQ, Wang DX Tags: Angew Chem Int Ed Engl Source Type: research
Copper-Catalyzed Radical Cross-Coupling of Redox-Active Oxime Esters, Styrenes and Boronic Acids.
Abstract A visible light-driven, copper-catalyzed three-component radical cross-coupling of oxime esters, styrenes, and boronic acids have been developed. Key steps of this protocol involve catalytic generation of iminyl radical from redox-active oxime ester and subsequent C-C bond cleavage to cyanoalkyl radical. Upon its addition to styrene, the newly formed benzylic radical undergoes coupling with boronic acid-derived ArCu(II) complex to achieve 1,1-diarylmethane-containing alkylnitriles. PMID: 30295976 [PubMed - as supplied by publisher] (Source: Angewandte Chemie)
Source: Angewandte Chemie - October 8, 2018 Category: Chemistry Authors: Xiao WJ, Yu XY, Zhao QQ, Chen J, Chen JR Tags: Angew Chem Int Ed Engl Source Type: research
HAT Reactions Via Photoredox Catalyzed Chlorine Atom Generation.
We report the mild, controlled, and catalytic generation of chlorine atoms as a new opportunity for access to a wide variety of hydrogen atom transfer (HAT) reactions owing to the high stability of HCl. The discovery of the photoredox mediated generation of chlorine atoms with Ir-based polypyridyl complex, [Ir(dF(CF3)ppy)2(dtbbpy)]Cl, under blue LED irradiation is reported. PMID: 30295981 [PubMed - as supplied by publisher] (Source: Angewandte Chemie)
Source: Angewandte Chemie - October 8, 2018 Category: Chemistry Authors: Barriault L, McCallum T, Rohe S, Morris A Tags: Angew Chem Int Ed Engl Source Type: research
Pd-Catalyzed Intermolecular Arylcarbonylation of Unactivated Alkenes: Incorporation of Bulky Aryls at Room Temperature.
Abstract A Pd-catalyzed intermolecular arylcarbonylation of unactivated alkenes has been established herein. Unsymmetric diaryliodonium salts (DAIS) are used as arylation reagents, in which the bulky aryls (ArL) are exclusively incorporated into the arylcarbonylated products bearing the ArL group and a carboxylic ester group at the α- and β-carbon position on the terminal C-C double bond, respectively. The reaction features excellent chemo- and regio-selectivities and high functional group tolerance under very mild reaction conditions. PMID: 30295983 [PubMed - as supplied by publisher] (Source: Angewandte Chemie)
Source: Angewandte Chemie - October 8, 2018 Category: Chemistry Authors: Liu G, Li X, Chen P Tags: Angew Chem Int Ed Engl Source Type: research
Constructing universal ionic sieves via alignment of two-dimensional covalent organic frameworks.
Abstract Shuttle effect of electrode materials always leads to capacity loss and poor cycle life of the batteries. Two-dimensional (2D) covalent organic frameworks (COFs) with uniform and controllable nanopores provide a promising strategy for fabricating ionic sieves to inhibit the shuttle effect. However, the insoluble nature of COFs made it difficult to fabricate compact and ordered membrane of COFs. Herein, we report a novel method for facilely anisotropic ordering of 2D COFs via depositing COFs onto graphene. The resulted double-layer membrane acting as ionic sieves impressively inhibits the shuttle effect an...
Source: Angewandte Chemie - October 8, 2018 Category: Chemistry Authors: Jiang C, Tang M, Zhu S, Zhang J, Wu Y, Chen Y, Xia C, Wang C, Hu W Tags: Angew Chem Int Ed Engl Source Type: research
Visible-Light-Driven, Copper-Catalyzed Decarboxylative C(sp3)-H Alkylation of Glycine and Peptides.
Abstract Despite a well-developed and growing body of work in Cu catalysis, the potential of Cu to serve as a photocatalyst remains underexplored. We here report the first example of visible-light-induced Cu-catalyzed decarboxylative C(sp3)-H alkylation of glycine for preparing α-alkylated unnatural α-amino acids. It merits mentioning that the mild conditions and the good functional group tolerance allow the modification of peptides using this method. The mechanistic studies revealed that a radical-radical coupling pathway was involved in the reaction. PMID: 30296349 [PubMed - as supplied by publi...
Source: Angewandte Chemie - October 8, 2018 Category: Chemistry Authors: Wang C, Guo M, Qi R, Shang Q, Liu Q, Wang S, Zhao L, Wang R, Xu Z Tags: Angew Chem Int Ed Engl Source Type: research
Spotlights on our sister journals: Angew. Chem. Int. Ed. 41/2018.
Authors: PMID: 30284402 [PubMed - in process] (Source: Angewandte Chemie)
Source: Angewandte Chemie - October 5, 2018 Category: Chemistry Tags: Angew Chem Int Ed Engl Source Type: research
Biomimetic Syntheses of ( ±)-Isopalhinine A, (±)-Palhinine A, and (±)-Palhinine D.
Biomimetic Syntheses of (±)-Isopalhinine A, (±)-Palhinine A, and (±)-Palhinine D. Angew Chem Int Ed Engl. 2018 Oct 04;: Authors: Chen CM, Shiao HY, Uang BJ, Hsieh HP Abstract The first total synthesis of isopalhinine A, as well as unified syntheses of palhinine A and palhinine D, have been successfully accomplished by way of a biomimetic strategy that proceeds through a bio-inspired 5/6/6/9 tetracyclic intermediate, which mimics the amino ketone form of palhinine D. An early-stage direct SN2 cyclization to construct the nine-membered azonane ring minimized the transannular strain ...
Source: Angewandte Chemie - October 4, 2018 Category: Chemistry Authors: Chen CM, Shiao HY, Uang BJ, Hsieh HP Tags: Angew Chem Int Ed Engl Source Type: research
An Electrophilic Bromine Redox Catalysis Manifold for Indole Alkaloid Building Blocks from Selective Aliphatic C-H Amination.
Abstract A new homogeneous bromine(-I/I) redox catalysis is described, which is based on monomeric bromine(I) compounds containing transferable phthalimidato groups. These catalysts enable intermolecular C-H amination reactions at previously unaccessible aliphatic positions and thus enlarge the synthetic potential of direct C-N bond formation including its application in alkaloid building block synthesis. This aspect is demonstrated for a new synthetic approach to aspidospermidine. In addition to the catalysis development, the structures of the involved bromine(I) compounds were fully elucidated including X-ray an...
Source: Angewandte Chemie - October 4, 2018 Category: Chemistry Authors: Muniz K, Berges J, Garcia B Tags: Angew Chem Int Ed Engl Source Type: research
Isomerism of the Aniline Trimer.
J, Fernández JA Abstract Weaker intermolecular forces permit expanded isomerization alternatives for molecular aggregation, as observed for the prototype models of the aniline trimer (An3) and the monohydrated aniline dimer (An2-W) when compared to the phenol trimer. These isolated trimers were generated in a jet-cooled neon expansion and probed using broadband (chirped-pulsed) microwave spectroscopy. Three isomers of the aniline trimer and two isomers of the hydrated dimer were detected and characterized in the spectrum. In the homotrimer the weak N-H···N hydrogen bonds are assisted b...
Source: Angewandte Chemie - October 3, 2018 Category: Chemistry Authors: Perez C, León I, Lesarri A, Pate BH, Martínez R, Millán J, Fernández JA Tags: Angew Chem Int Ed Engl Source Type: research
Composition Tailoring via N & S Co-doping and Structure Tuning by Constructing Hierarchical Pores Enable Metal-free Catalysts for High-Performance Electrochemical Reduction of CO2.
We report a facile route to scalable production of N and S co-doped, hierarchically porous carbon nanofiber (NSHCF) mem-branes (i.e., ~400 cm2 membrane in a single process). As-synthesized NSHCF membranes are flexible and free-standing, rendering their direct use as cathodes for efficient electrochemical CO2 reduction reaction (CO2RR). Notably, CO with 94% Faradaic efficiency and -103 mA cm-2 current density are readily achieved with only ~1.2 mg catalyst loading, which are among the best results ever obtained by metal-free CO2RR catalysts. On the basis of control experiments and DFT calculations, such outstanding CO Farad...
Source: Angewandte Chemie - October 3, 2018 Category: Chemistry Authors: Yang H, Wu Y, Lin Q, Fan L, Chai X, Zhang Q, Liu J, He C, Lin Z Tags: Angew Chem Int Ed Engl Source Type: research
A Janus Nickel Cobalt Phosphide Catalyst for High-efficiency Neutral-pH Water Splitting.
Abstract Transition metal phosphides have demonstrated great interest as catalysts to drive the hydrogen evolution reaction (HER), but their use as bifunctional catalytic electrodes that enable efficient neutral-pH water splitting has rarely been achieved. Herein, we report the synthesis of ternary Ni0.1Co0.9P porous nanosheets onto conductive carbon fiber paper that can efficiently and robustly catalyze both the HER and water oxidation in 1 M phosphate buffer (PBS; pH 7) electrolyte under ambient conditions. A water electrolysis cell comprising such Ni0.1Co0.9P electrodes demonstrates remarkable activity and stab...
Source: Angewandte Chemie - October 3, 2018 Category: Chemistry Authors: Yu SH, Wu R, Xiao B, Gao Q, Zheng Y, Zheng X, Zhu J, Gao MR Tags: Angew Chem Int Ed Engl Source Type: research
Construction of Linear and Branched Tetraboranes via 1,1- and 1,2-Diboration of Diborenes.
Abstract Sterically unencumbered diborenes based on a benzylphosphine chelate undergo diboration reactions with bis(catecholato)diboron in the absence of a catalyst to yield tetraboranes. The symmetrical diborenes studied undergo 1,2-diborations, whereas an unsymmetrical derivative was found to yield a triborylborane-phosphine adduct as the result of a formal 1,1-diboration. A related borylborylene compound also underwent a 1,2-diboration to produce a borylene-borane adduct. PMID: 30276985 [PubMed - as supplied by publisher] (Source: Angewandte Chemie)
Source: Angewandte Chemie - October 2, 2018 Category: Chemistry Authors: Stennett TE, Bertermann R, Braunschweig H Tags: Angew Chem Int Ed Engl Source Type: research
Metal-Free, Visible-Light-Induced Remote C(sp3)-H Pyridylation via Radical Translocation of N-Alkoxypyridinium Salts.
Abstract Metal-free, visible-light-induced site-selective heteroarylation of remote C(sp3)-H bonds has been accomplished through the design of N-alkoxyheteroarenium salts serving as both alkoxy radical precursors and heteroaryl sources. The transient alkoxy radical can be generated via the single electron reduction of an N-alkoxypyridinium substrates by a photoexcited quinolinone catalyst. Subsequent radical translocation of the alkoxy radical forms a nucleophilic alkyl radical intermediate, which undergoes addition to the substrate to achieve remote C(sp3)-H heteroarylation. This cascade strategy provides a power...
Source: Angewandte Chemie - October 2, 2018 Category: Chemistry Authors: Kim I, Park B, Kang G, Kim J, Jung H, Lee H, Baik MH, Hong S Tags: Angew Chem Int Ed Engl Source Type: research
Solid-Phase Conversion of Four Stereoisomers into a Single Enantiomer.
Abstract Viedma ripening is an emerging method for the solid phase deracemization of mixtures of enantiomers. Up to now, the scope of the method has remained limited to molecules with a single stereocenter. We show here that the method can be extended to obtain a single enantiomer from a mixture of stereoisomers with two different stereocenters. In addition, we show that using tailor-made chiral additives, the conversion time can be reduced by a factor of 100. PMID: 30277304 [PubMed - as supplied by publisher] (Source: Angewandte Chemie)
Source: Angewandte Chemie - October 2, 2018 Category: Chemistry Authors: Engwerda T, Mertens H, Tinnemans P, Meekes H, Rutjes FPJT, Vlieg E Tags: Angew Chem Int Ed Engl Source Type: research
A Clade II-D Fungal Chimeric Diterpene Synthase from Colletotrichum gloeosporioides Making Dolasta-1(15),8-diene.
Abstract Based on a terpenoid overproduction platform in yeast for genome mining, a chimeric diterpene synthase from the endophytic fungus Colletotrichum gloeosporioides ES026 was characterized as (5R,12R,14S)-dolasta-1(15),8-diene synthase. The absolute configuration was independently verified by use of enantioselectively deuterated terpene precursors which unequivocally established the predicted C1-III-IV cyclization mode for this first characterized clade II-D enzyme. Extensive isotopic labeling experiments and isolation of the intermediate (1R)-δ-araneosene supported the proposed cyclization mechanism. ...
Source: Angewandte Chemie - October 2, 2018 Category: Chemistry Authors: Bian G, Rinkel J, Wang Z, Lauterbach L, Hou A, Yuan Y, Deng Z, Liu T, Dickschat JS Tags: Angew Chem Int Ed Engl Source Type: research
Metal phosphorous trichalcogenides (MPCh3): from synthesis to contemporary energy challenges.
fer Z Abstract Layered two-dimensional (2D) materials have been establish as the most significant topic in materials science for the current decade, arising to their unique physical and chemical properties. From mono-element (graphene, phosphorene, etc.) to the more commonly found containing two (metal dichalcogenides) or even further elements. A distinctive class of 2D layered materials are the metal phosphorous trichalcogenides (MPCh3, Ch=S, Se), first synthetized in the late 1800s. Having an unusual intercalation behavior, MPCh3 were intensively studied in the 1970s for their magnetism and as secondary electrod...
Source: Angewandte Chemie - October 2, 2018 Category: Chemistry Authors: Pumera M, Gusmão R, Sofer Z Tags: Angew Chem Int Ed Engl Source Type: research
PIP2-Induced Tau Filaments Probed by Tip-Enhanced Raman Spectroscopy.
Abstract The morphology and the secondary structure of peptide fibers formed by aggregation of Tau fragments (K18), in the presence of the inner cytoplasmic membrane phosphatidylinisitol component (PIP2) or heparin sodium (HS) as co-factors, are determined with nanoscale (
Source: Angewandte Chemie - October 2, 2018 Category: Chemistry Authors: Talaga D, Smeralda W, Lescos L, Hunel J, Lepejova-Caudy N, Cullin C, Bonhommeau S, Lecomte S Tags: Angew Chem Int Ed Engl Source Type: research
Palladium-Catalyzed Enantioselective Addition of Chiral Metal Enolates to In Situ Generated Ortho-Quinone Methides.
We describe herein a conceptually novel, cooperative Brønsted acid-base catalyzed process for the conjugate addition of cyclic β-keto esters to in situ generated ortho-quinone methides. Upon hemiacetalization densely functionalized chiral chromans with two adjacent quaternary and additionally a tertiary stereogenic center were obtained with very good diastereoselectivity (up to>95:5 d.r.) and typically excellent enantioselectivity (up to>99% ee). The striking feature and key to success is the dual catalytic activation of both nucleophile and electrophile in two separate cycles with a single chiral catalys...
Source: Angewandte Chemie - October 2, 2018 Category: Chemistry Authors: Schneider C, Göricke F Tags: Angew Chem Int Ed Engl Source Type: research
Synthesis of the Campylobacter jejuni 81-176 strain capsular polysaccharide repeating unit reveals the absolute configuration of its O-methyl phosphoramidate motif.
We report the synthesis of the three repeating units found in C. jejuni 81-176 CPS; one of these possesses a MeOPN group. In the course of these studies we established that the stereochemistry of the phosphorus atom in this MeOPN group is R. These studies represent the first unequivocal proof of stereochemistry of this group in any C. jejuni CPS. The compounds produced are anticipated to be useful tools in investigations targeting the function and biosynthesis of this structurally-interesting modification, which so far has only been identified in campylobacter. PMID: 30280458 [PubMed - as supplied by publisher] (Sourc...
Source: Angewandte Chemie - October 2, 2018 Category: Chemistry Authors: Thota VN, Ferguson MJ, Sweeney RP, Lowary T Tags: Angew Chem Int Ed Engl Source Type: research
N6-methyladenosine-sensitive RNA-cleaving deoxyribozymes.
MT Abstract Deoxyribozymes are synthetic enzymes made of DNA that can catalyze the cleavage or formation of phosphodiester bonds and are useful tools for RNA biochemistry. Here we report new RNA-cleaving deoxyribozymes to interrogate the methylation status of target RNAs, thereby providing an alternative method for the biochemical validation of RNA methylation sites containing N6-methyladenosine, which is the most wide-spread and extensively investigated natural RNA modification. Using in vitro selection from random DNA, we developed deoxyribozymes that are sensitive to the presence of N6-methyladenosine in RNA n...
Source: Angewandte Chemie - October 1, 2018 Category: Chemistry Authors: Höbartner C, Sednev MV, Mykhailiuk V, Choudhury P, Halang J, Sloan KE, Bohnsack MT Tags: Angew Chem Int Ed Engl Source Type: research
Palladium-Catalyzed Tandem Divergent Cyclopropanation via Solvent-Driven Regioselective C(sp3)-H Bond Activation.
We report a palladium-catalyzed tandem Heck/regioselective C(sp3)-H activation for divergent synthesis of spiro- and fused-cyclopropanated indolines from N-methallylated 2-bromoarylamides. The regioselectivity of the C-H bond activation of σ-alkylPd(II) intermediate could be controlled by the choice of the solvent used. DFT calculations suggest that the polarity of solvent molecules could influence the transition state energy, leading to a bifurcation of the C-H bond activation by the σ-alkylPd(II) intermediate. PMID: 30276944 [PubMed - as supplied by publisher] (Source: Angewandte Chemie)
Source: Angewandte Chemie - October 1, 2018 Category: Chemistry Authors: Chung DS, Lee JS, Ryu H, Park J, Kim H, Lee JH, Kim UB, Lee WK, Baik MH, Lee SG Tags: Angew Chem Int Ed Engl Source Type: research
Mannich-type Reactions of Cyclic Nitrones: Effective Methods for the Enantioselective Synthesis of Piperidine-containing Alkaloids.
Abstract Although there are dozens of biologically active 2-substituted and 2,6-disubstituted piperidines, only a limited number of approaches exist for their synthesis. Herein is described two Mannich-type additions to nitrones, one using β-ketoacids under catalyst-free conditions and another using methyl ketones in the presence of chiral thioureas, which can generate a broad array of such 2-substituted materials, as well as other ring variants, in the form of β-N-hydroxy-aminoketones. Both processes have broad scope, with the latter providing products with high enantioselectivity (up to 98%). The combi...
Source: Angewandte Chemie - October 1, 2018 Category: Chemistry Authors: Lisnyak VG, Lynch-Colameta T, Snyder SA Tags: Angew Chem Int Ed Engl Source Type: research
Modulating Electronic Structures of Inorganic Nanomaterials for Efficient Electrocatalytic Water Splitting.
Abstract Electrocatalytic water splitting is one of the most promising sustainable energy conversion technologies, but is limited by the sluggish electrochemical reactions. Inorganic nanomaterials have been widely used as efficient catalysts for promoting the electrochemical kinetics. Several approaches to optimize activities of these nanocatalysts have been developed. The electronic structures of the catalysts play a pivotal role in governing the activity and thus have been identified as an essential descriptor. However, the underlying working mechanisms related to the refined electronic structures remain elusive...
Source: Angewandte Chemie - October 1, 2018 Category: Chemistry Authors: Du X, Huang J, Zhang J, Yan Y, Wu C, Hu Y, Yan C, Lei T, Chen W, Fan C, Xiong J Tags: Angew Chem Int Ed Engl Source Type: research
[Co@Sn6Sb6]3-: An Off-Center Endohedral 12-Vertex Cluster.
We report on the asymmetric occupation of a 12-vertex cluster centered by a single metal atom. Three salts of related intermetalloid cluster anions, [Co@Sn6Sb6]3- (1), [Co2@Sn5Sb7]3- (2), and [Ni2@Sn7Sb5]3- (3) were synthesized, which have pseudo-C4v-symmetric or pseudo-D4h-symmetric 12-vertex Sn/Sb shells and interstitial Co- ions or Ni atoms. 1 is a very unusual single-metal-"centered" 12-atom cluster, with the inner atom being clearly offset from the cluster center for energetic reasons. Quantum chemistry served to determine atomic positions and relative stabilities of this cluster type. The studies indicate t...
Source: Angewandte Chemie - October 1, 2018 Category: Chemistry Authors: Dehnen S, Wilson RJ, Hastreiter F, Reiter K, Büschelberger P, Wolf R, Gschwind R, Weigend F Tags: Angew Chem Int Ed Engl Source Type: research
Across-the-world automated optimization and continuous flow synthesis of pharmaceutical agents operating through a cloud-based server.
Abstract The power of the Cloud has been harnessed for pharmaceutical compound production with remote servers based in Tokyo, Japan being left to autonomously find optimal synthesis conditions for three active pharmaceutical ingredients (APIs) in laboratories in Cambridge, UK. A researcher located in Los Angeles, USA controlled the entire process via an internet connection. The constituent synthetic steps for Tramadol, Lidocaine and Bupropion were thus optimized with minimal intervention from operators within hours, yielding conditions satisfying customizable evaluation functions for all examples. PMID: 30272...
Source: Angewandte Chemie - October 1, 2018 Category: Chemistry Authors: Fitzpatrick DE, Maujean T, Evans A, Ley SV Tags: Angew Chem Int Ed Engl Source Type: research
Iodospirocyclization of Tryptamine-Derived Isocyanides: Formal Total Synthesis of Aspidofractinine.
Abstract The N-iodosuccinimide-mediated spirocyclization of tryptamine-derived isocyanides to generate spiroindolenines is reported. The products contain both an imine and an imidoyl iodide as flexible handles for follow-up chemistry. Nucleophilic addition typically occurs chemoselectively on the imine moiety with complete diastereoselectivity, providing opportunities for the construction of complex molecular frameworks. The synthetic potential of the method was showcased in the formal total synthesis of (±)-aspidofractinine. PMID: 30273989 [PubMed - as supplied by publisher] (Source: Angewandte Chemie)
Source: Angewandte Chemie - October 1, 2018 Category: Chemistry Authors: Saya JM, Roose TR, Peek JJ, Weijers B, de Waal TJS, Vande Velde CML, Orru RVA, Ruijter E Tags: Angew Chem Int Ed Engl Source Type: research
Spotlights on our sister journals: Angew. Chem. Int. Ed. 40/2018.
Authors: PMID: 30251478 [PubMed - in process] (Source: Angewandte Chemie)
Source: Angewandte Chemie - September 28, 2018 Category: Chemistry Tags: Angew Chem Int Ed Engl Source Type: research
Decarboxylative Negishi Coupling of Redox-Active Aliphatic Esters by Cobalt Catalysis.
Abstract A cobalt-catalyzed decarboxylative Negishi coupling reaction of redox-active aliphatic esters with organozinc reagents was developed. The method enabled efficient alkyl-aryl, alkyl-alkenyl, and alkyl-alkynyl coupling reactions under mild reaction conditions with no external ligand or additive needed. The success of an in situ activation protocol and the facile synthesis of the drug molecule (±)-preclamol highlight the synthetic potential of this method. Mechanistic studies indicated that a radical mechanism is involved. PMID: 30252190 [PubMed - in process] (Source: Angewandte Chemie)
Source: Angewandte Chemie - September 28, 2018 Category: Chemistry Authors: Liu XG, Zhou CJ, Lin E, Han XL, Zhang SS, Li Q, Wang H Tags: Angew Chem Int Ed Engl Source Type: research
Development of an Alkyne-de Mayo Reaction for the Synthesis of Medium-Sized Carbacycles and Cyclohepta[b]indoles.
Abstract Embedded medium-sized carbacycles and cyclohepta[b]indoles are frequently occurring scaffold elements in natural products and bioactive compounds. Herein, we reveal a conceptionally novel photochemically triggered cascade process to these scaffolds. The cascading ring expansion process rests on an unprecedent intramolecular alkyne-de Mayo reaction. PMID: 30259622 [PubMed - as supplied by publisher] (Source: Angewandte Chemie)
Source: Angewandte Chemie - September 27, 2018 Category: Chemistry Authors: Hiersemann M, Tymann D, Tymann DC, Bednarzick U, Iovkova-Berends L, Rehbein J Tags: Angew Chem Int Ed Engl Source Type: research
Isolation of Tetracyano-Naphthalenediimide and its Ambient Stable Planar Radical Anion.
Abstract Herein we report the first isolation of tetracyano-naphthalenediimide [NDI(CN)4] and its radical anion and structural elucidation through spectroscopic and X-ray diffraction studies. The radical anion showed remarkable ambient stability and could be purified by chromatography, which is unique for planar radical anions. The stability is bestowed by multiple H-bonds with the counter ion and through an array of intramolecular noncovalent interactions. The radical anion revealed one of the strongest NDI pi-pi interactions (3.268 Å). Electrochemical studies of [NDI(CN)4] confirmed its extraordinarily low...
Source: Angewandte Chemie - September 27, 2018 Category: Chemistry Authors: Mukhopadhyay P, Kumar Y, Kumar S, Mandal K Tags: Angew Chem Int Ed Engl Source Type: research
A new N-heterocyclic carbene-based silver precursor and its validation in atmospheric pressure plasma enhanced spatial atomic layer deposition of silver thin films.
Abstract A new N-heterocyclic carbene-based (NHC) silver amide compound 1,3-di-tert-butyl-imidazolin-2-ylidene silver(I) 1,1,1-trimethyl-N-(trimethylsilyl) silanaminide [(NHC)Ag(hmds)] was synthesized and analysed by single-crystal X-ray diffraction, ¹H, ¹³C NMR, EI mass spectroscopy and subsequently evaluated for its thermal characteristics. This new halogen and phosphine free Ag ALD precursor was tested successfully for silver thin film growth in atmospheric pressure plasma enhanced spatial (APP) ALD that has a huge potential for high-volume low-cost manufacturing. High purity conductive Ag thin f...
Source: Angewandte Chemie - September 27, 2018 Category: Chemistry Authors: Boysen N, Hasselmann T, Karle S, Rogalla D, Theirich D, Winter M, Riedl T, Devi A Tags: Angew Chem Int Ed Engl Source Type: research
Two-Terminal Molecular Memory via Reversible Switching of Quantum Interference Features in Tunneling Junctions.
Abstract This paper describes large-area molecular tunneling junctions comprising self-assembled monolayers of redox-active molecules that exhibit two-terminal bias switching. The as-prepared monolayers undergo partial charge-transfer to the underlying metal substrate (Au, Pt or Ag) that converts their cores from a quinoid to hydroquinoid form. The resulting rearomatization converts the bond topology from a cross-conjugated to linearly-conjugated π system. The cross-conjugated form correlates to appearance of an interference feature in the transmission spectrum that vanishes in the linear-conjugated form. Due t...
Source: Angewandte Chemie - September 27, 2018 Category: Chemistry Authors: Carlotti M, Soni S, Kumar S, Ai Y, Sauter E, Zharnikov M, Chiechi RC Tags: Angew Chem Int Ed Engl Source Type: research
Enantioselective, Catalytic Vicinal Difluorination of Alkenes.
r R Abstract The enantioselective, catalytic vicinal difluorination of alkenes is reported via I(I)/I(III) catalysis using a novel, C2-symmetric resorcinol derivative. Catalyst turnover via in situ generation of an ArI(III)F2 species is enabled by Selectfluor® oxidation and addition of an inexpensive HF•amine complex. The HF•amine ratio employed in this Umpolung process provides a handle for regioselective orthogonality as a function of Brønsted acidity. Selectivity reversal from the 1,1-difluorination pathway (geminal) to the desired 1,2-difluorination (vicinal) is disclosed (>20:1 in both...
Source: Angewandte Chemie - September 26, 2018 Category: Chemistry Authors: Scheidt F, Schäfer M, Sarie J, Daniliuc C, Molloy J, Gilmour R Tags: Angew Chem Int Ed Engl Source Type: research
Diastereoselective Aza-Mislow-Evans Rearrangement of N-Acyl-tert-Butanesulfinamides into α-Sulfenyloxy Carboxamides.
Diastereoselective Aza-Mislow-Evans Rearrangement of N-Acyl-tert-Butanesulfinamides into α-Sulfenyloxy Carboxamides. Angew Chem Int Ed Engl. 2018 Sep 26;: Authors: Tang F, Yao Y, Xu YJ, Lu CD Abstract A diastereoselective [2,3]-rearrangement of O-silyl N-sulfinyl N,O-ketene acetals derived from chiral N-acyl-tert-butanesulfinamides was developed, giving α-sulfenyloxyl carboxamides with excellent enantioselectivities. Enolization and subsequent silylation of N-acyl-tert-butanesulfinamides initiate the aza-variant of Mislow-Evans rearrangement, in which the chirality of the sulfur in the rea...
Source: Angewandte Chemie - September 26, 2018 Category: Chemistry Authors: Tang F, Yao Y, Xu YJ, Lu CD Tags: Angew Chem Int Ed Engl Source Type: research
Asymmetric Enzymatic Hydration of Unactivated, Aliphatic Alkenes.
Abstract The direct enantioselective addition of water to unactivated alkenes could simplify the synthesis of chiral alcohols and solve a long-standing challenge in catalysis. Here we report that an engineered fatty acid hydratase can catalyze the asymmetric hydration of various terminal and internal alkenes. In the presence of a carboxylic acid "decoy molecule" for activation of the oleate hydratase from E. meningoseptica, asymmetric hydration of unactivated alkenes was achieved with up to 93% conversion, excellent selectivity (>99% ee,>95% regioselectivity) and on preparative scale. PMID: 30...
Source: Angewandte Chemie - September 26, 2018 Category: Chemistry Authors: Demming RM, Hammer SC, Nestl BM, Gergel S, Fademrecht S, Pleiss J, Hauer B Tags: Angew Chem Int Ed Engl Source Type: research
Intermolecular Allylic C-H Etherification of Internal Olefins.
Abstract Herein we report on the development of an oxidative allylic C-H etherification reaction, utilizing internal olefins and alcohols as simple precursors. Key advances include the use of RhCp* complexes to promote the allylic C-H functionalization of internal olefins and the compatibility of the oxidative conditions with oxidatively sensitive alcohols, enabling the direct etherification reaction. Preliminary mechanistic studies, consistent with C-H functionalization as the rate determining step, are presented. PMID: 30256503 [PubMed - as supplied by publisher] (Source: Angewandte Chemie)
Source: Angewandte Chemie - September 26, 2018 Category: Chemistry Authors: Nelson T, Blakey SB Tags: Angew Chem Int Ed Engl Source Type: research
A Supramolecular Approach to Preparation of Nanographene Adlayers Using Water-soluble Molecular Capsules.
Abstract Polycyclic aromatic hydrocarbons (PAHs) are excellent building blocks for the creation of two-dimensional (2D) nanosheets. However, large PAHs tend to exhibit poor or no solubilities in organic solvents and water. To overcome this issue, in this study, we employed water-soluble micellar capsules consisting of V-shaped amphiphilic molecules. Characteristic electrochemical behaviors were observed in 0.1 M H₂SO₄ in the presence of the water-soluble capsules containing PAHs such as ovalene, circobiphenyl, and dicoronylene. Furthermore, under these conditions, PAHs were released from the capsules, resultin...
Source: Angewandte Chemie - September 26, 2018 Category: Chemistry Authors: Origuchi S, Kishimoto M, Yoshizawa M, Yoshimoto S Tags: Angew Chem Int Ed Engl Source Type: research
Grouping effect of single Ni-N4 sites in N-doped carbons boosts hydrogen transfer coupling of alcohols and amines.
Abstract As a new type of heterogeneous catalyst with "homogeneous-like" activity, single-site transition metal materials were usually treated as integrated but separated active centers. Herein, we report a novel grouping effect of single Ni-N4 sites in N-doped carbon (Ni/NC), where effective ligand-stabilized polycondensation method endows Ni/NC nanocatalysts with a high content of single-site Ni up to 9.5 wt. %. The enhanced electron density at each single Ni-N4 site promotes a highly efficient hydrogen transfer, here exemplified with the coupling of benzyl alcohol and aniline into N-benzyl aniline wit...
Source: Angewandte Chemie - September 25, 2018 Category: Chemistry Authors: Su H, Gao P, Wang MY, Zhai GY, Zhang JJ, Zhao TJ, Su J, Antonietti M, Li XH, Chen JS Tags: Angew Chem Int Ed Engl Source Type: research