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Practical pure shift NMR experiments, especially on instruments equipped with cryoprobes, can sometimes give very disappointing results. Here we show for the first time that this is a consequence of signal loss due to sample convection, and demonstrate a simple adjustment to common pure shift NMR experiments that restores the lost signal. [ABSTRACT FROM AUTHOR]

In this work, we report our latest results regarding the self‐assembly properties of two Ru‐acetylides complexes and their corresponding free organic ligands, in solution and in the solid state. The four compounds show mesogenic properties, which we have rationalized thanks to extensive DSC, SAXS, POM, FTIR and molecular dynamic investigations. We clearly establish that hydrogen bonds stabilize the supramolecular structures, and that introducing the metal center and its coordination sphere induces large change in the liquid crystal properties. In addition, for the monoacetylide compound Ru2, solution‐state studies helped us rationalize its supramolecular abilities. In particular, we demonstrate that Ru2 follows an isodesmic growth supramolecular polymerization in aromatic solvent. [ABSTRACT FROM AUTHOR]

We report the straightforward one‐pot synthesis of novel 5‐ or 6‐membered P‐heterocycles featuring an internal ylidic bond: P‐containing acenaphthylenes and phenanthrenes. The stability of the compounds tolerates post‐functionalization through direct arylation to introduce electron‐rich/poor substituents and the synthetic strategy is also compatible with the preparation of more elaborate polyaromatic scaffolds such as acenes and helicenes. Using a joint experimental (X‐ray analysis, optical and redox properties) and theoretical approach, we perform a full structure–property relationships study on these new platforms. In particular, we show that molecular engineering allows not only tuning their absorption/emission across the entire visible range but also endowing them with chiroptical or non‐linear optical properties, making them valuable dyes for a large panel of photonic or opto‐electronic applications. [ABSTRACT FROM AUTHOR]

We report the straightforward one‐pot synthesis of novel 5‐ or 6‐membered P‐heterocycles featuring an internal ylidic bond: P‐containing acenaphthylenes and phenanthrenes. The stability of the compounds tolerates post‐functionalization through direct arylation to introduce electron‐rich/poor substituents and the synthetic strategy is also compatible with the preparation of more elaborate polyaromatic scaffolds such as acenes and helicenes. Using a joint experimental (X‐ray analysis, optical and redox properties) and theoretical approach, we perform a full structure–property relationships study on these new platforms. In particular, we show that molecular engineering allows not only tuning their absorption/emission across the entire visible range but also endowing them with chiroptical or non‐linear optical properties, making them valuable dyes for a large panel of photonic or opto‐electronic applications. [ABSTRACT FROM AUTHOR]

A family of cyclic phosphine‐disiloxane featuring peri‐substituted naphthyl(Nap)/acenaphthyl(Ace) scaffolds has been prepared and fully characterized including X‐ray structure, which enables a detailed structural analysis. This straightforward synthesis takes advantage of both ortho‐ and peri‐substitution of Nap/Ace‐substituted phosphine oxides. The synthetic method allows diversifying the polycyclic aromatic platform (Nap and Ace) as well as the Si substituents (Me and Ph). Despite a strong steric congestion, the P‐atom remains reactive toward oxidation or coordination. In particular, Au(I) complex could be prepared. All the compounds display absorption/luminescence in the UV‐Vis range. Surprisingly, the P‐trivalent derivatives display unexpected luminescence in the green in solid‐state. [ABSTRACT FROM AUTHOR]

A halogen‐bond templated 1:1 macrocyclization in solution is reported. Tetra(iodoperfluorophenyl) ethers were used as halogen‐bonded exotemplates in a substoichiometric amount (5 mol %). Pyridine‐containing macrocyclic architectures were formed by ruthenium‐catalyzed tandem metathesis/transfer hydrogenation sequence using sodium borohydride and methanol as non‐dihydrogen hydrogen source. The halogen‐bonded stabilization energies were analyzed relying on density functional theory. [ABSTRACT FROM AUTHOR]

A halogen‐bond templated 1:1 macrocyclization in solution is reported. Tetra(iodoperfluorophenyl) ethers were used as halogen‐bonded exotemplates in a substoichiometric amount (5 mol %). Pyridine‐containing macrocyclic architectures were formed by ruthenium‐catalyzed tandem metathesis/transfer hydrogenation sequence using sodium borohydride and methanol as non‐dihydrogen hydrogen source. The halogen‐bonded stabilization energies were analyzed relying on density functional theory. [ABSTRACT FROM AUTHOR]

π ligands such as olefins and alkynes bind intramolecularly to the metal atom in d 0 complexes of the large alkaline earths (Ae) calcium and strontium supported by fluoroalkoxo ligands with dangling unsaturated C-C or C-C bonds, and having the amide N(SiMe2H)2 - as the coligand. These O-bridged dinuclear complexes are further stabilized by secondary C-F→Ae and β-Si-H···Ae interactions. In a set of structurally related Ca-olefin complexes, the strength of these interactions gradually increases as the coordination of the olefin onto Ca2+ becomes weaker (from η²-coordinated to η¹ to fully dissociated) upon increasing steric congestion, thus ensuring that overwhelming electronic depletion does not occur at calcium. NMR data imply that the olefins are metal-bound in [D8]toluene solutions. The Ae···Cπ, C-F→Ae, and β-Si-H···Ae noncovalent interactions are also strong in the parent Ae-alkyne complexes, the first examples of non-acetylide Ae-alkynes compounds. Calcium-arene complexes could not be made, as the aromatic tether did not bind to the metal atom. Instead, a trinuclear complex with noninteracting C6H5 groups was obtained. It exhibits exceptionally strong C-F→Ca and β-Si-H···Ca interactions. NMR data indicate that the congeneric calcium-allene complex can be made, but it spontaneously isomerizes toward the more stable Ca-alkyne via an unusual 1,3-hydride shift intramolecular process. [ABSTRACT FROM AUTHOR]

Investigations based on NMR spectroscopy, mass spectrometry, and DFT calculations shed light on the metallic species generated in the rhodium-catalyzed asymmetric [2+2+2] cycloaddition reaction between diynes and isocyanates with the chiral phosphate TRIP. The catalytic mixture comprising [{Rh(cod)Cl}2], 1,4-diphenylphosphinobutane (dppb), and Ag( S)-TRIP actually gives rise to two species, both having an effect on the stereoselectivity. One is a rhodium(I) complex in which TRIP is a weakly coordinating counterion, whereas the other is a bimetallic Rh/Ag complex in which TRIP is a strongly coordinating X-type ligand. [ABSTRACT FROM AUTHOR]

The photophysical and chiroptical properties of a novel, chiral helicene‐NHC−Re(I) complex bearing an N‐(aza[6]helicenyl)‐benzimidazolylidene ligand are described, showing its ability to emit yellow circularly polarized luminescence. A comparative analysis of this new system with other helicene‐Re(I) complexes reported to date illustrates the impact of structural modifications on the emissive and absorptive properties. [ABSTRACT FROM AUTHOR]

Ag–N-heterocyclic carbene(NHC) complexes can occur as neutral[(NHC)AgX] and/or ionic [(NHC)2Ag][AgX2] speciesin solution. Herein, the behavior of four complexes bearing commonbulky N,N′-diaryl NHCs wasexamined in DMSO. 1H NMR experiments performed systematicallyin CDCl3and in DMSO-d6wereused to detect DMSO or chloride ion induced equilibration betweenthe neutral and ionic forms at very different time scales. We observedthat solubilization of IMesAgCl and SIMesAgCl in DMSO at 300 K ledin less than a few minutes to a complete equilibration. Here, magnetizationexchange rate constants were determined from EXSY experiments. Incontrast, IPrAgCl and SIPrAgCl, which possess more bulky NHCs, werefound to exhibit much lower exchange rates (or no exchange) at 300K. IPrAgCl was shown to slowly generate an increasing amount of homolepticcationic complex in DMSO for several hours before reaching equilibrium.In this case, the initial rate of formation of the cationic complexwas determined. [ABSTRACT FROM AUTHOR]

The stability over lime (repeatability) for the determination of site-specific 13C/12C ratios at natural abundance by quantitative 13C NMR spectroscopy has been tested on three probes: enriched bilabeled [1 ,2-13C2]ethanol; ethanol at natural abundance; and vanillin at natural abundance. It is shown in all three cases that the standard deviation for a series of measurements taken every 2-3 months over periods between 9 and 13 months is equal to or smaller than the standard deviation calculated from 5-10 replicate measurements made on a single sample. The precision which can be achieved using the present analytical 13C NMR protocol is higher than the prerequisite value of 1-2‰ for the determination of site-specific 13C/12C ratios at natural abundance (13C-SNIF-NMR). Hence, this technique permits the discrimination of very small variations in 13C/12C ratios between carbon positions, as found in biogenic natural products. This observed stability over time in 13C NMR spectroscopy indicates that further improvements in precision will depend primarily on improved signal-to-noise ratio. [ABSTRACT FROM AUTHOR]

Abstract: In order to detect small variations in 13C isotopomers concentrations, high sensitivity, accuracy and precision have to be achieved. To assess such criteria, when using 13C NMR, 13C bi-labelled ethanol has been proposed as a molecular probe. Advantage has been taken of the pre-established structural relationship between the peak areas of the 13C NMR spectrum of this molecule, i.e. the ratio of signal areas is set to a fixed value. It is shown that the quality performance, required by quantitative 13C NMR spectroscopy, is not affected by a large reduction of the repetition delay using relaxation reagents. [Copyright &y& Elsevier]

Abstract: The strategy for the measurement of the site-specific isotope ratios by NMR within a symmetrical molecule is illustrated by the determination of the site-specific 13C content in glycerol on the basis of (i) a selective derivatisation of glycerol, carried out by a lipase (Candida antarctica) to overcome the symmetry of the molecule, (ii) purification of the (R)-monobenzoate glycerol with a high enantiomeric excess and (iii) use of this derivative for quantitative 13C NMR spectroscopy for the determination of 13C isotopomer concentrations. [Copyright &y& Elsevier]

Recently, we disclosed the uncatalyzed formation of polyaminoboranes (PABs) from monomeric diisopropylaminoborane (iPr2N−BH2) and primary amines (RNH2). Their structure is studied through a detailed multinuclear NMR study and their full spectroscopic characterization is presented revealing that N‐alkyl substituted PABs exhibit magnetically non‐equivalent methylenic protons in the close vicinity of the BN‐backbone. We also performed an in‐depth theoretical study of this global chemical process. The mechanism is fully apprehended and the strong influence of the temperature on the outcome of the reaction is unveiled. DFT‐calculations clearly show that the formation of the polyaminoboranes (RNH−BH2)n results from a kinetically controlled step‐growth polymerization reaction that can be globally viewed as a head‐to‐tail association process of the in situ generated transient monomeric monoalkylamino‐borane [RNH−BH2]. [ABSTRACT FROM AUTHOR]

We here present how rebalancing the interplay between H‐bonds and dispersive forces (Van der Waals/π–π stacking) may induce or not the generation of kinetic metastable states. In particular, we show that extending the aromatic content and favouring the interchain VdW interactions causes a delay into the cooperative supramolecular polymerization of a new family of toluene bis‐amide derivatives by trapping the metastable inactive state. [ABSTRACT FROM AUTHOR]

We here present how rebalancing the interplay between H‐bonds and dispersive forces (Van der Waals/π–π stacking) may induce or not the generation of kinetic metastable states. In particular, we show that extending the aromatic content and favouring the interchain VdW interactions causes a delay into the cooperative supramolecular polymerization of a new family of toluene bis‐amide derivatives by trapping the metastable inactive state. [ABSTRACT FROM AUTHOR]

Band-selective (bs) HSQC, improving spectral resolution by restriction of the heteronuclear dimension without inducing spectral folding, has been recently used for polymer tacticity determination. Herein is reported an evaluation of various bs-HSQC and bs-HMBC sequences, first from a methodological point of view (selectivity, dependence to INEPT interpulse delay or relaxation delay), using the cyclic peptide cyclosporin selected as a model compound, and then from an applicative approach, comparing tacticity determined from bs-HSQC and bs-HMBC experiments to the one obtained from 1D 13C{1H} on poly(3-hydroxyalkanoate)s samples. For HSQC sequences, the 13C selectivity scheme consisting in substituting a 13C broadband refocalization by a selective one revealed itself problematic, with unwanted aliased signals, whereas the insertion of double pulsed field gradients spin-echo (DPFGSE) or the use of opposite sign gradients bracketing a selective refocalization gave satisfactory results. Determination of the probability of syndiotactic enchainments, Ps, by bs-HSQC is fully consistent and no precision loss was observed when decreasing acquisition time (37 min vs. 106 min for 1D 13C{1H}). Bs-HMBC, although not straightforwardly applicable for tacticity determination, could provide (after a calibration step) an alternative for compounds of which only 13C carbonyl signals are resolved enough for discriminating between syndiotactic and isotactic configurations. [ABSTRACT FROM AUTHOR]

We report the straightforward synthesis of unprecedented electron‐acceptors based on dicationic P‐containing PAHs (Polycyclic Aromatic Hydrocarbons) based on copper mediated radical approach. In these systems, two phosphoniums are connected through various PAHs backbones. The impact of π‐extension on both the optical and redox properties is investigated using a joint experimental (UV/Vis absorption, fluorescence and cyclic voltammetry) and theoretical approach (TD‐DFT calculations). Finally, (spectro)‐electrochemical studies prove that these compounds possess three redox states and EPR studies confirm the in situ formation of an organic radical delocalized on the PAH backbone. [ABSTRACT FROM AUTHOR]

Novel [4, 6]helicenes (4a,b) bearing a fused imidazolium unit have been prepared from [4, 6]helicene‐2,3‐di‐n‐propyl‐amines 3a,b. The in situ formation of N‐heterocyclic carbene (NHC) derivatives followed by their complexation to iridium(I) or rhodium(I) gave access to complexes 1a, 1′a, and 1b, containing mono‐coordinated helicene‐NHC, chloro and COD (COD = 1,5‐cyclooctadiene) ligands. Ir and Rh complexes 1a and 1′a were characterized by X‐ray crystallography. HPLC and NMR analyses showed that Ir(I) complex 1b existed as a mixture of two diastereomeric complexes corresponding to enantiomeric pairs M‐(−)/P‐(+)‐1b1 and M‐(−)/P‐(+)‐1b2 which differ by the position of COD through space. The chiroptical properties (electronic circular dichroism and optical rotation) of the four stereoisomers were measured. These complexes were also tested as catalysts in a transfer hydrogenation reaction. [ABSTRACT FROM AUTHOR]

The article presents a research which examines the site-specific unexpected 13 carbon (C) isotopic fractionation by nuclear magnetic resonance (13C SNIF-NMR). Accordingly, the research evaluates the site-by-site variation of fractionation at natural abundance by two common physical processes including distillation and column chromatography. The researchers used isotope ratio mass spectrometry (IRMS) to determine the isotope effect.

2‐Amino[2.2]paracyclophane reacts with salicylaldehyde or 2‐hydroxyacetophenone to yield imines that then give access to a new series of boranils (8b–d) upon complexation with BF2. These novel boron‐containing compounds display both planar and axial chiralities and were examined experimentally and computationally. In particular, their photophysical and chiroptical properties were studied and compared to newly prepared, simpler boranils (9a–d) exhibiting axial chirality only. Less sophisticated chiral architectures were shown to demonstrate overall stronger circularly polarized luminescence (CPL) activity. [ABSTRACT FROM AUTHOR]

Enantiopure copper(I) chloride complexes bearing a monodentate N-(carbo[6]helicenyl)–NHC ligand have been prepared and characterized experimentally and computationally. Their high stability enables the stereochemistry to be probed by X-ray crystallography and NMR spectroscopy. The resolved enantiomeric complexes emit circularly polarized blue fluorescence with glum ∼1.3 × 10−3 in solution. The photophysical and chiroptical properties of these systems, with their helicene-centred origin, are similar to those of the organic helicene-benzimidazole precursor proligand, although the reverse axial chirality configuration is preferentially observed for the complex compared to the ligand. [ABSTRACT FROM AUTHOR]

Strontium and calcium (alkaline earth: Ae) olefin complexes stabilised by secondary Ae⋅⋅⋅F−C and β-agostic Ae⋅⋅⋅H−Si interactions are presented. Olefin coordination onto the alkaline earths is plain in the solid state, and it is thermodynamically favoured over the coordination of THF. The existence of the Ae⋅⋅⋅olefin interactions is corroborated by solution NMR data and DFT computations. The coordination mode of the olefin varies with steric effects and, if enforced, olefin dissociation can be compensated by the other non-covalent interactions, as supported by DFT computations. [ABSTRACT FROM AUTHOR]

2-(1H-benzo[d]imidazol-2-yl)quinoline (BQ) as ligand and three coordination compounds of formula {Zn(BQ)Cl2} (1), {Pb(BQ)Cl2}n (2) and {[Cu(BQ)2(OC(O)CH3)]OC(O)CH3 · CH3COOH} (3) have been synthesized and fully characterized. The complexes crystallize in triclinic space group P 1 ‾ $P‾{1}$. In complexes 1 and 2, the coordination geometry is a distorted tetrahedral environment around the zinc center and a distorted sixfold coordination geometry around the lead center, respectively. In complex 3 the central Cu(II) center is in a trigonal bipyramidal coordination geometry. The Cu(II) ion is surrounded by two bidentate 2-(2′-quinolyl)benzimidazole (BQ) ligands and one coordinated acetate molecule. One further acetate anion associated by a strong hydrogen bond with a molecule of acetic acid balances the charge of the compound. [ABSTRACT FROM AUTHOR]

We present the stereospecific synthesis of helicenoid-based phosphepines (7-membered P-rings) as well as chiral P-containing polycyclic aromatic hydrocarbons. In these systems, an axial to central chirality transfer takes place from the BINAP moiety to the P-atom. The impact of the molecular design on the structure, the (chir)optical (including circularly polarized luminescence) and redox properties are investigated. [ABSTRACT FROM AUTHOR]

Mono‐ and di‐boranil‐substituted helicenes were prepared by BF2‐borylation of the corresponding anils, readily synthesized by condensation of 2‐amino‐ and 2,15‐diamino‐helicenes with 4‐(diethylamino)salicylaldehyde. After enantiomeric resolution using HPLC, their chiroptical properties including circularly polarized fluorescence in solution and in PMMA films were investigated and rationalized with the help of NMR, X‐ray and quantum‐chemical calculations. [ABSTRACT FROM AUTHOR]

A series of four D–(π-Pt–π-A)2 new V-shaped binuclear platinum(II) complexes bearing a diphenylpyranylidene ligand as a pro-aromatic donor group (D) and various electron-attracting groups (A) separated by platinum bis-acetylide fragments have been synthesized, characterized and studied for their electrochemical, photophysical and second-order nonlinear optical (NLO) properties. The nonlinear optical properties of these complexes have been determined by using the Electric-Field-Induced Second Harmonic (EFISH) generation technique, and their optical properties have been rationalized by Time-Dependent Density Functional Theory (TD-DFT) calculations relying on a range-separated hybrid. All complexes display positive μβ0 values. In addition, the second-order NLO responses of the complexes could be easily modulated by incorporating various end-capped electron-attracting groups, namely malononitrile, indane-1,3-dione, pyrimidine and pyrimidinium. Remarkably, complex 7 bearing a pyrimidinium fragment displays the highest μβ0 value among all the complexes of this series. Its NLO response is twice as high as that of the mononuclear analogue complex RD2, which has been confirmed both experimentally and theoretically. [ABSTRACT FROM AUTHOR]

The first enantiopure chiral‐at‐rhenium complexes of the form fac‐ReX(CO)3(:C^N) have been prepared, where :C^N is a helicene‐N‐heterocyclic carbene (NHC) ligand and X=Cl or I. These have complexes show strong changes in the emission characteristics, notably strongly enhanced phosphorescence lifetimes (reaching 0.7 ms) and increased circularly polarized emission (CPL) activity, as compared to their parent chiral models lacking the helicene unit. The halogen along with its position within the dissymmetric stereochemical environment strongly affect the photophysics of the complexes, particularly the phosphorescence quantum yield and lifetime. These results give fresh insight into fine tuning of photophysical and chiroptical properties of Re‐NHC systems. [ABSTRACT FROM AUTHOR]

The first enantiopure chiral‐at‐rhenium complexes of the form fac‐ReX(CO)3(:C^N) have been prepared, where :C^N is a helicene‐N‐heterocyclic carbene (NHC) ligand and X=Cl or I. These have complexes show strong changes in the emission characteristics, notably strongly enhanced phosphorescence lifetimes (reaching 0.7 ms) and increased circularly polarized emission (CPL) activity, as compared to their parent chiral models lacking the helicene unit. The halogen along with its position within the dissymmetric stereochemical environment strongly affect the photophysics of the complexes, particularly the phosphorescence quantum yield and lifetime. These results give fresh insight into fine tuning of photophysical and chiroptical properties of Re‐NHC systems. [ABSTRACT FROM AUTHOR]

2,3-Diphenylated quinoxaline, pyrido[2,3-b]pyrazine and 8-bromopyrido[3,4-b]pyrazine were halogenated in deprotometalation-trapping reactions using mixed 2,2,6,6-tetramethyl piperidino-based lithium-zinc combinations in tetrahydrofuran. The 2,3-diphenylated 5-iodo- quinoxaline, 8-iodopyrido[2,3-b]pyrazine and 8-bromo-7-iodopyrido[3,4-b]pyrazine thus obtained were subjected to palladium-catalyzed couplings with arylboronic acids or anilines, and possible subsequent cyclizations to afford the corresponding pyrazino[2,3-a]carbazole, pyrazino[2′,3′:5,6] pyrido[4,3-b]indole and pyrazino[2′,3′:4,5]pyrido[2,3-d]indole, respectively. 8-Iodopyrido[2,3-b] pyrazine was subjected either to a copper-catalyzed C-N bond formation with azoles, or to direct substitution to introduce alkylamino, benzylamino, hydrazine and aryloxy groups at the 8 position. The 8-hydrazino product was converted into aryl hydrazones. Most of the compounds were evaluated for their biological properties (antiproliferative activity in A2058 melanoma cells and disease-relevant kinase inhibition). [ABSTRACT FROM AUTHOR]

Abstract: N‐Aryl‐N‐methyl‐2‐tert‐butyl‐6‐methylaniline derivatives exhibit a rotationally stable N−C axially chiral structure and the rotational barriers around an N−C chiral axis increased with the increase in electron‐withdrawing character of para‐substituent on the aryl group. X‐ray crystal structural analysis and the DFT calculation suggested that the considerable change of the rotational barriers by the electron effect of para‐substituents is due to the disappearance of resonance stabilization energy caused by the twisting of para‐substituted phenyl group in the transition state. This structural property of the N−C axially chiral anilines was employed to reveal a new acid‐decelerated molecular rotor caused by the protonation at the remote position (remote proton brake). [ABSTRACT FROM AUTHOR]

A fused π-helical N-heterocyclic carbene (NHC) system was prepared and examined through its diastereoisomerically pure cycloiridiated complexes. The latter display light-green phosphorescence with unusually long lifetimes and circular polarization that depends on both the helical NHC P/ M stereochemistry and the iridium Δ/Λ stereochemistry. These unprecedented features are attributed to extended π conjugation within the helical carbenic ligand and efficient helicene-NHC-Ir interaction. [ABSTRACT FROM AUTHOR]

A fused π-helical N-heterocyclic carbene (NHC) system was prepared and examined through its diastereoisomerically pure cycloiridiated complexes. The latter display light-green phosphorescence with unusually long lifetimes and circular polarization that depends on both the helical NHC P/ M stereochemistry and the iridium Δ/Λ stereochemistry. These unprecedented features are attributed to extended π conjugation within the helical carbenic ligand and efficient helicene-NHC-Ir interaction. [ABSTRACT FROM AUTHOR]

The first helicene–NHC–iridium complexes have been prepared in enantiopure forms. Their stereochemical, electronic, and chiroptical features were characterized experimentally and via first-principles calculations, highlighting the helical and iridium-centered chirality. [ABSTRACT FROM AUTHOR]

The Kinugasa reaction, applied to propargylic gem-difluorides, allows a very direct and efficient synthesis of new exoalkylidene β-lactams with a fluorine in the vinylic position. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cross metathesis of bio-sourced sterically hindered cyclic terpenes and terpenoids with internal (functional) olefins. • Ruthenium-catalyzed olefin metathesis. • Green chemistry: catalytic transformations of abundant natural products. • High regio- and stereoselectivity. The straightforward functionalization of sterically demanding α,α-disubstituted double bonds of β-pinene, (-)-limonene and (-)-limonene terpenoids has been achieved via cross metathesis with internal olefins. The reactions are catalyzed by second generation ruthenium catalysts in dimethyl carbonate as green solvent or under neat conditions. This transformation provides a clean process for the access to functionalized bulky cyclic terpenes where the terminal double bond generates a trisubstituted olefin. [ABSTRACT FROM AUTHOR]

Frontispiz: Long-Lived Circularly Polarized Phosphorescence in Helicene-NHC Rhenium(I) Complexes: The Influence of Helicene, Halogen, and Stereochemistry on Emission Properties Keywords: circularly polarized emission; helicenes; N-heterocyclic carbenes; phosphorescence; rhenium(I) EN circularly polarized emission helicenes N-heterocyclic carbenes phosphorescence rhenium(I) 1 1 1 05/18/20 20200525 NES 200525 B Chiroptische Verbindungen b In ihrer Zuschrift auf S. 8472 beschreiben J. A. G. Williams, J. Autschbach, J. Crassous et al. die Synthese von Rhenium(I)/NHC-Helicen-Komplexen mit zirkular polarisierter Phosphoreszenz sowie photophysikalische Untersuchungen dieser Verbindungen. Circularly polarized emission, helicenes, N-heterocyclic carbenes, phosphorescence, rhenium(I). [Extracted from the article]

Innentitelbild: Long-Lived Circularly Polarized Phosphorescence in Helicene-NHC Rhenium(I) Complexes: The Influence of Helicene, Halogen, and Stereochemistry on Emission Properties (Angew. Keywords: circularly polarized emission; helicenes; N-heterocyclic carbenes; phosphorescence; rhenium(I) EN circularly polarized emission helicenes N-heterocyclic carbenes phosphorescence rhenium(I) 8382 8382 1 05/18/20 20200525 NES 200525 B Zeitaufgelöste impulsive b stimulierte Raman-Spektroskopie, eine ultraschnelle Raman-Technik, ermöglicht es, Momentaufnahmen von Molekülen im angeregten Zustand mit hoher Empfindlichkeit und Zeitauflösung zu gewinnen. Circularly polarized emission, helicenes, N-heterocyclic carbenes, phosphorescence, rhenium(I). [Extracted from the article]

The reactivity of Cyproheptadine and Cyclobenzaprine in Pd-catalyzed arylation via C-H bond functionalizations was investigated. From Cyproheptadine using aryl bromides as aryl sources and 5 mol% of a palladium catalyst, the C10-arylated Cyproheptadine derivatives were regioselectively obtained. The highest yields were obtained with electron-rich aryl bromides, but the reaction tolerated useful functional groups on the aryl bromide such as dimethylamino, methoxy, hydroxyl, alkyl, aryl, fluoro, chloro and trifluoromethyl. Cyclobenzaprine was also reactive under the same reaction conditions. © 2019 Elsevier Science. All rights reserved. Unlabelled Image • First regioselective arylations at the C10-position of Cyproheptadine. • One step access to Cyproheptadine congeners. • Good functional group tolerance. • Air and moisture tolerant Pd-catalyst. [ABSTRACT FROM AUTHOR]

A new enantiopure cyclometallated iridium complex bearing a [4]helicenic :C∧C- ‐coordinating and two :N∧C- ‐coordinating dfppy (2‐(2,4‐difluorophenyl)‐pyridyl) ligands was prepared. This complex displayed long‐lived phosphorescence both in solution and in the solid state. Its chiroptical properties, namely electronic circular dichroism and circularly polarized luminescence, were also examined. Comparison with former chiral complexes enabled assignment of the ΔIr‐(−) and ΛIr‐(+) absolute configurations. [ABSTRACT FROM AUTHOR]

Propargylic gem-difluorides are applied to the Kinugasa reaction affording novel exoalkylidene β-lactams with a fluorine in the vinylic position. [ABSTRACT FROM AUTHOR]