Search

The C−F bond of acyl fluorides can be cleaved and added across tethered alkenes in the presence of a cationic rhodium(I) tetrafluoroborate catalyst. This 1,2‐carbofluorination reaction offers a powerful method for the synthesis of tertiary alkyl fluoride derivatives with an atom economy of 100 %. Mechanistic studies indicate that the concerted action of a rhodium cation and a tetrafluoroborate anion is key for the success of this catalytic cleavage and formation of C−F bonds in a controlled manner. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Chemical transformation of polyaromatic hydrocarbon (PAH) molecules following different reaction strategies has always been the focus of organic synthesis. In this work, we report the synthesis of a PAH molecule, formation of which consists of an unusual C−C bond cleavage accompanied by a complex π‐conjugated molecular scaffold rearrangement. We demonstrate that the complex chemical transformation is steered by concerted motion of individual Au0 gold atoms on a supporting Au(111) surface. This observation underpins the importance of single‐atom catalysis mediated by adatoms in on‐surface synthesis as well as catalytic activity of single Au0 atoms facilitating cleavage of covalent carbon bonds. [ABSTRACT FROM AUTHOR]

We report a formal carbon–carbon (C−C) bond insertion via the reaction of secondary benzylic halides (fluorides, chlorides, and bromides) with α‐diazo esters catalyzed by Lewis acid catalysts. Secondary benzylic halides underwent elongation to afford α,β‐diaryl‐β‐haloesters diastereoselectively. Density functional theory calculation revealed that the present formal C−C bond insertion was the result of Lewis acid‐promoted cleavage and the re‐formation of a carbon–halogen bond and that the aryl‐migration step determined the diastereoselectivity. Various diarylmethyl halides and α‐diazo esters were applicable to this reaction system. In addition, ring expansion in cyclic benzylic chlorides was accomplished. [ABSTRACT FROM AUTHOR]

In this work, a universal strategy for solid, solution, or gel state organic persistent luminescent materials via radiative energy transfer is proposed. The persistent luminescence (τ>0.7 s) could be remotely regulated between different colors by controlling the isomerization of the energy acceptor. The function relies on the simple radiative energy transfer (reabsorption) mechanism, rather than the complicated communication between the excited state of the molecules such as Förster resonance energy transfer or Dexter energy transfer. And the "apparent lifetime" for the energy acceptor is the same as the lifetime of the energy donor, which was different with a traditional radiative energy transfer process. The simple working principle endows this strategy with huge universality, flexibility, and operability. This work offers a simple, feasible, and universal way to construct various persistent luminescent materials in solid, solution, and gel states. [ABSTRACT FROM AUTHOR]

Incorporation of structurally novel noncanonical amino acids (ncAAs) into proteins is valuable for both scientific and biomedical applications. To expand the structural diversity of available ncAAs and to reduce the burden of chemically synthesizing them, we have developed a general and simple biosynthetic method for genetically encoding novel ncAAs into recombinant proteins by feeding cells with economical commercially available or synthetically accessible aromatic thiols. We demonstrate that nearly 50 ncAAs with a diverse array of structures can be biosynthesized from these simple small‐molecule precursors by hijacking the cysteine biosynthetic enzymes, and the resulting ncAAs can subsequently be incorporated into proteins via an expanded genetic code. Moreover, we demonstrate that bioorthogonal reactive groups such as aromatic azides and aromatic ketones can be incorporated into green fluorescent protein or a therapeutic antibody with high yields, allowing for subsequent chemical conjugation. [ABSTRACT FROM AUTHOR]

A strong conjugation present in fused systems plays a crucial role in tuning of the properties that would be showing a dependence on the efficiency of π‐electrons coupling. The π‐cloud available in the final structure can be drastically influenced by a side‐ or a linear fusion of unsaturated and conjugated hydrocarbons. The linear welding of naphthalene/anthracene or quinoxaline/benzo[g]quinoxaline with triphyrin(2.1.1) gives structures where the competition between local and global delocalization is distinguished. The aromatic character observed in skeletons strongly depends on the oxidation state of the macrocyclic flanking and is either extended over the whole system or kept as a composition of local currents (diatropic and paratropic) of incorporated units. The hybrid systems show the properties derived from the π‐conjugations that interlace one another but also show a significant independence of (aza)acene subunits reflected in the observed spectroscopic properties. [ABSTRACT FROM AUTHOR]

The one‐pot synthesis of a series of sulfonium salts containing transferable diazomethyl groups is described, and the structure of these compounds is elucidated by X‐ray crystallography. Under photochemical conditions, reaction of these salts with N,N‐dialkyl hydrazones affords 1‐(dialkylamino)‐1,2,3‐triazoles via diazomethyl radical addition to the azomethine carbon followed by intramolecular ring closure. The straightforward transformation of the structures thus obtained into mesoionic carbene–metal complexes is also reported and the donor properties of these new ligands characterized. [ABSTRACT FROM AUTHOR]

Di‐2,7‐naphthihexaphyrin(1.1.1.1.1.1), a non‐aromatic carba‐analogue of the hexaphyrin(1.1.1.1.1.1), incorporating two built‐in 2,7‐naphthylene moieties was synthesized as two separate, conformationally locked stereoisomers. Both conformers followed complex protonation pathways involving structurally different species, which can be targeted under kinetic and thermodynamic control. The neutralization of the ultimate dicationic product, accessible from both stereoisomers of the free base, allowed to realize the complex conformational switching cycle involving six structurally different species. [ABSTRACT FROM AUTHOR]

The dealkenylative alkenylation of alkene C(sp3)−C(sp2) bonds has been an unexplored area for C−C bond formation. Herein 64 examples of β‐alkylated styrene derivatives, synthesized through the reactions of readily accessible feedstock olefins with β‐nitrostyrenes by ozone/FeII‐mediated radical substitutions, are reported. These reactions proceed with good efficiencies and high stereoselectivities under mild reaction conditions and tolerate an array of functional groups. Also demonstrated is the applicability of the strategy through several synthetic transformations of the products, as well as the syntheses of the natural product iso‐moracin and the drug (E)‐metanicotine. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A copper complex of a heterocorrole analogue with an N–N linkage, 1,19‐diaza‐21,24‐dicarbadibenzocorrole (Cu‐5), was successfully synthesized via oxidative metalation–cyclization of a tetrapyrrolic precursor. The N–N linkage in the skeleton of Cu‐5, which serves as a mediator of π‐electron delocalization, features an 18π aromatic system. The electronic structure of Cu‐5 is best described as a ground‐state singlet species stabilized by the distinct NNCC coordination core. This finding shows how the ligand's design can be used to modulate the Cu 3dx2-y2 orbital energy, thereby making such compounds invaluable for copper‐based catalytic applications. [ABSTRACT FROM AUTHOR]

Unprecedented dual aggregation‐induced emission (AIE) behavior based on a steric‐hindrance photochromic system is presented, with incorporation one or two bulky aryl groups, resulting in different flexibleness. The dual AIE behavior of open and closed isomers can be explained by restriction of intramolecular rotation (RIR), restriction of intramolecular vibration (RIV), and intermolecular stacking. The large bulky benzothiophene causes restricted rotation, enhancing the emission of open form in solution and weak π–π molecular packing, thereby efficiently enhancing the luminescence performance in the solid state. With incorporation of two large bulky benzothiophene groups, BBTE possesses the most outstanding AIE activity, undergoing highly efficient and reversible off‐to‐on fluorescence in film upon alternating UV and visible light irradiation along with excellent fatigue resistance. The off‐to‐on fluorescent photoswitch is successfully established in super resolution imaging. [ABSTRACT FROM AUTHOR]

Benzoxepane derivatives were designed and synthesized, and one hit compound emerged as being effective in vitro with low toxicity. In vivo, this hit compound ameliorated both sickness behavior through anti‐inflammation in LPS‐induced neuroinflammatory mice model and cerebral ischemic injury through anti‐neuroinflammation in rats subjected to transient middle cerebral artery occlusion. Target fishing for the hit compound using photoaffinity probes led to identification of PKM2 as the target protein responsible for anti‐inflammatory effect of the hit compound. Furthermore, the hit exhibited an anti‐neuroinflammatory effect in vitro and in vivo by inhibiting PKM2‐mediated glycolysis and NLRP3 activation, indicating PKM2 as a novel target for neuroinflammation and its related brain disorders. This hit compound has a better safety profile compared to shikonin, a reported PKM2 inhibitor, identifying it as a lead compound in targeting PKM2 for the treatment of inflammation‐related diseases. [ABSTRACT FROM AUTHOR]

A novel and unusual palladium‐catalyzed [4+2] annulation of cyclopropenes with benzosilacyclobutanes is reported. This reaction occurred through chemoselective Si−C(sp2) bond activation in synergy with ring expansion/insertion of cyclopropenes to form new C(sp2)−C(sp3) and Si−C(sp3) bonds. An array of previously elusive bicyclic skeleton with high strain, silabicyclo[4.1.0]heptanes, were formed in good yields with excellent diastereoselectivity under mild conditions. An asymmetric version of the reaction with a chiral phosphoramidite ligand furnished a variety of chiral bicyclic silaheterocycle derivatives with good enantioselectivity (up to 95.5:4.5 er). Owing to the mild reaction conditions, the good stereoselectivity profile, and the ready availability of the functionalized precursors, this process constitutes a useful and straightforward strategy for the synthesis of densely functionalized silacycles. [ABSTRACT FROM AUTHOR]

The ability to use mechanical strain to steer chemical reactions creates completely new opportunities for solution‐ and solid‐phase synthesis of functional molecules and materials. However, this strategy is not readily applied in the bottom‐up on‐surface synthesis of well‐defined nanostructures. We report an internal strain‐induced skeletal rearrangement of one‐dimensional (1D) metal–organic chains (MOCs) via a concurrent atom shift and bond cleavage on Cu(111) at room temperature. The process involves Cu‐catalyzed debromination of organic monomers to generate 1,5‐dimethylnaphthalene diradicals that coordinate to Cu adatoms, forming MOCs with both homochiral and heterochiral naphthalene backbone arrangements. Bond‐resolved non‐contact atomic force microscopy imaging combined with density functional theory calculations showed that the relief of substrate‐induced internal strain drives the skeletal rearrangement of MOCs via 1,3‐H shifts and shift of Cu adatoms that enable migration of the monomer backbone toward an energetically favorable registry with the Cu(111) substrate. Our findings on this strain‐induced structural rearrangement in 1D systems will enrich the toolbox for on‐surface synthesis of novel functional materials and quantum nanostructures. [ABSTRACT FROM AUTHOR]

The diversity‐oriented desulfonylative functionalization of alkyl allyl sulfones with various sulfone‐type reagents by radical chemistry has been developed. The readily installed allylsulfonyl moiety acts as a C‐radical precursor, which is substituted by various functionalities using sulfur‐based radical trapping reagents. The generality of this approach is documented by the successful desulfonylative alkynylation, azidation, trifluoromethylthiolation, sulfenylation, trifluoromethylselenylation, halogenation, and deuteration. The method is compatible with a wide range of functional groups. Considering the deuteration, products are obtained in good yields with a high level of deuterium incorporation. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: The rapid development of enantioselective C−H activation reactions has created a demand for new types of catalysts. Herein, we report the synthesis of a novel planar‐chiral rhodium catalyst [(C5H2tBu2CH2tBu)RhI2]2 in two steps from commercially available [(cod)RhCl]2 and tert‐butylacetylene. Pure enantiomers of the catalyst were obtained through separation of its diastereomeric adducts with natural (S)‐proline. The catalyst promoted enantioselective reactions of aryl hydroxamic acids with strained alkenes to give dihydroisoquinolones in high yields (up to 97 %) and with good stereoselectivity (up to 95 % ee). [ABSTRACT FROM AUTHOR]

Abstract: An expanded porphyrinoid has been obtained by a simple ring expansion from a contracted porphyrinoid, namely corrole. Spectroscopic, structural, and computational investigations reveal peculiar π‐conjugation and geometry. The effect of extended π‐conjugation is evident from perturbed redox behavior and photophysical properties. Owing to the strong diatropic ring current of the corrole and cross‐conjugation, the molecule exhibits a non‐aromatic nature for the expanded π‐circuit, as evident from NMR studies. [ABSTRACT FROM AUTHOR]

Pyrrole-modified subporphyrins bearing a non-pyrrolic cyclic unit, subporpholactone, subporpholactam, and imidazolosubporphyrin were newly synthesized. They show subporphyrin-like absorption and fluorescence spectra that are red-shifted in the order of subporpholactamF4 (ArF=3,5-bis(trifluoromethyl)phenyl) and two isomeric carbene complexes in the presence of KPF6. [ABSTRACT FROM AUTHOR]

A novel [36]octaphyrin analogue embedding two N-confused pyrrole units demonstrated unique prototropy-coupled isomerization between the Figure-of-eight and dumbbell conformers. Upon bis-metal coordination, fixation of fully π-conjugated Figure-of-eight structures was achieved as referred from the X-ray crystal structure. Chirogenesis of the helical enantiomers was proved by intense circular dichroism (CD) response in the near infrared (NIR) region. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Complexation of novel multiply N-confused expanded calix[ n]phyrins with boron difluoride afforded a new class of cyclic BODIPY (boron-dipyrromethene) arrays. The structures of circularly arranged BODIPY subunits linked in an N-confused fashion give rise to such photophysical properties unique to the macrocycles as redshifted emission wavelengths along with apparent large Stokes shifts, long emission lifetimes, and solid-state lasing. The DFT calculations support the size-dependent excited-state dynamics of the macrocycles. [ABSTRACT FROM AUTHOR]

In the search of porphyrin arrays with a unique geometry, the efficient synthesis of a directly linked 21-carba-23-thiaporphyrin dimer with the distinctive dihydrofulvalene bridging motif has been developed. This compound acquires an uncommon parallel-displaced arrangement of two carbaporphyrin planes. The dimer undergoes an acid-triggered cleavage to create of the asymmetric carbathiaporphyrin-carbathiachlorin dyad or 2,3-dihalo-21-carba-23-thiachlorin depending on choice of acid. A formation of a reactive carbocation intermediate is postulated to account for mechanism of cleavage. [ABSTRACT FROM AUTHOR]

Three kinds of fused porphyrinoids, L2- L4, possessing different types of corrole-based frameworks were synthesized from a pyrrole-substituted corrole isomer (norrole L1). Oxidation of L1 afforded a unique N-Cmeso-fused pyrrolyl isonorrole L2, involving the fusion of an auxiliary pyrrolic NH moiety with a meso-sp3-hybridized carbon atom. Subsequently, L2 underwent macrocycle transformations to give singly and doubly N-CAr-fused N-confused corroles, L3 and L4, respectively. L3 and L4 contain fused [5.7.6.5]-tetra- and [5.6.7.7.6.5]-hexacyclic structures, respectively, prepared through lateral annulation. These skeletal transformation reactions from norrole to its isomer isonorrole and finally to N-confused corrole indicate that multiply fused porphyrinoids could be readily synthesized from pyrrole-appended confused porphyrinoids. [ABSTRACT FROM AUTHOR]

In the corroie homologue, 6,11,16-triarylbipyricorrole, the bipyrrole unit is replaced by a 2,2-bipyridine unit. This modification effectively alters the corrole N4 coordination sphere from the trianionic [(NH)3N] to the monoanionic [N3NH] state. The newly formed monoanionic core stabilizes ZnII ions with enhanced emission properties. The enhanced emission was further utilized for metal ion sensing studies and exploited for the selective detection of ZnII ions. [ABSTRACT FROM AUTHOR]

An adj-dicarbacorrole with CCNN in the core is achieved by replacing the bipyrrole moiety by a simple polycyclic aromatic hydrocarbon, such as biphenyl unit. Spectroscopic studies and structural analyzes confirm the absence of macrocyclic aromatization, thus leading to overall nonaromatic character. The trianionic core is effectively utilized to stabilize a copper(III) ion to form an organocopper complex. [ABSTRACT FROM AUTHOR]

The first syntheses of hybrid structures that lie between subphthalocyanines and subporphyrins are reported. The versatile single-step synthetic method uses a preformed aminoisoindolene to provide the bridging methine unit and its substituent while trialkoxyborates simultaneously act as Lewis acid, template, and provider of the apical substituent. The selection of each component therefore allows for the controlled formation of diverse, differentially functionalized systems. The new hybrids are isolated as robust, pure materials that display intense absorption and emission in the mid-visible region. The new compounds are further characterized in solution and solid state by variable-temperature NMR spectroscopy and X-ray crystallography, respectively. [ABSTRACT FROM AUTHOR]

A contracted doubly N-confused dioxohexaphyrin derivative served as a dinucleating metal ligand for unsymmetrical coordination. The complexation of two palladium(II) cations led to the formation of π-radical species that were persistent in atmospheric air in the presence of moisture. Effective delocalization of an unpaired electron over the hexaphyrin backbone could contribute to the distinct chemical stability. [ABSTRACT FROM AUTHOR]

An understanding of fundamental aspects of archetypal organic structural motifs remains a key issue faced by the experimental and theoretical chemists. Two possible bonding modes for a disubstituted benzene ring, that is a meta and para, determines the π delocalization for oligomeric structures. When the less abundant ortho-substituted variant is introduced into a triphyrin(2.1.1) skeleton an aromatic molecule is obtained and the carbocyclic ring participates in the conjugation of the macrocycle. The two-electron reduction and introduction of boron(III) changes the aromatic character and results in an anti-aromatic structure which has been confirmed by single-crystal analysis and supported by theoretical calculations. [ABSTRACT FROM AUTHOR]

The first neo-confused hexaphyrin(1.1.1.1.1.0) was synthesized by oxidative ring closure of a hexapyrrane bearing two terminal 'confused' pyrroles. The new compound displays a folded conformation with a short interpyrrolic C⋅⋅⋅N distance of 3.102 Å, and thus it readily underwent ring fusion to afford a neo-fused hexaphyrin with an unprecedented 5,5,5,7-tetracyclic ring structure. Furthermore, coordination of CuII triggered a ring opening/contracting reaction to afford a CuII complex of an N-linked pentaphyrin derivative. The roles of reactive NC bonds in the porphyrinoid macrocycles were demonstrated. [ABSTRACT FROM AUTHOR]

Triangularly shaped, contracted porphyrinoids belong to a group of molecules where the geometry significantly modifies the observed electronic properties. The need for a controllable, effective, and widely applicable approach to triphyrins drives extensive research towards macrocyclic materials that act as potential controlling motifs by switching their aromaticity. Two isomeric thiophene-fused triphyrins(2.1.1) were synthesized by applying an innovative approach. Spectroscopic techniques (NMR, UV/Vis) show that both macrocycles are aromatic and quantitatively convert into anti-aromatic structures after reduction with a zinc amalgam. The reduced forms were stabilized through boron(III) coordination, thereby allowing the observation of anti-aromatic 16 π delocalization within a contracted porphyrin. [ABSTRACT FROM AUTHOR]

In jeden Hinsicht verwirrt: Während Dipyrrin Metallionen koordiniert (links), geht sein N ‐ Stellungsisomer in Gegenwart verschiedener Metallsalze eine Cyclomerisierung unter Bildung expandierter NCNCNC ‐ und NCNCNCNC ‐ Norrole ein (rechts). Diese neuartigen Isomere von Rosarin (24 π) und Octaphyrin (32 π) mit C ‐ N ‐ verknüpften Bipyrroleinheiten und im Festkörper fast planarer Konformation zeigen paratrope Ringströme, die für antiaromatische Porphyrinoide typisch sind. [ABSTRACT FROM AUTHOR]

Ein Semiferrocen ‐ Komplex mit einem [14]Triphyrin(2.1.1) ‐ Liganden (TriP) wurde synthetisiert und Röntgen ‐ strukturanalytisch charakterisiert. Seine Eigenschaften wurden mit UV/Vis ‐ und temperaturabhängiger 1H ‐ NMR ‐ Spektroskopie untersucht. Die FeII ‐ und FeIII ‐ Komplexe sind elektrochemische reversibel. [ABSTRACT FROM AUTHOR]

The article discusses a unique pyrrolic rearrangement reaction induced in palladium of a singly to a doubly nitrogen(N)-confused hexaphyrin. It mentions the discovery of the reaction during a study on palladium coordination chemistry of singly N-confused [26]hexaphyrin. It mentions the important role played by sp3-hybridized carbon atom formation at the meso position and reduction from [26]hexaphyrin to [28]hexaphyrin in the reaction.

Krumme Kristalle: Große Einkristalle eines einfachen organischen kleinen Moleküls gehen ein lichtinduziertes Verbiegen ein (siehe Bild). Der Biegeprozess wird von einem starken visuellen Fluoreszenzkontrast begleitet, was für die Ferndetektion photomechanischer Arbeit genutzt werden kann. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Vererbte Chiralität: Der Chiralitätstransfer von Methyllactat auf Ammoniak wurde anhand der spiegelbildlichen Schwingungs ‐ Circulardichroismus(VCD) ‐ Spektren eines Paares von Enantiomeren des flexiblen chiralen Molekülkomplexes untersucht. Die charakteristischen VCD ‐ Muster liefern Beweise für die Existenz zweier dominanter und geringfügig verschiedener Konformere des Komplexes. [ABSTRACT FROM AUTHOR]