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Complex [Ag(IPr)( 3-Me dpa)][PF 6 ] (1), possessing the same combination of ligands as previously reported [Cu(IPr)( 3-Me dpa)][PF 6 ] (2) applied in a blue-emitting light-emitting electrochemical cell (LEC), has been synthesized and fully structurally and photophysically characterized both in powder and thin-film form. In detail, temperature-dependent steady-state, time-resolved emission experiments, and computational calculations have been performed to understand the impact of the nature of the metal ion center on the photophysical and electroluminescent properties. Here, a direct comparison between the complexes reveals (i) a distinct emission behavior, such as fluorescence (1) vs . thermally activated delay fluorescence (2), caused by the changes of the nature of the emitting excited states from ligand centered (1) to metal-to-ligand charge transfer (2), (ii) an unforeseen crystallinity-dependent emission in 1 that leads to either smooth and non-emissive thin-films or phase aggregated and emissive thin-films, and (iii) 1-based LECs with a stable electrical behavior over 100 h, which contrasts with the prior start-of-the-art value of a few minutes (2).

Here we report an iron-complex-catalyzed synthesis of various mono- and di-substituted quinolin-2(1 H )-ones achieved via the intramolecular acceptorless dehydrogenative cyclization of amido-alcohols. This approach for the synthesis of N-heterocycles has provided access to underdescribed disubstituted quinolinones and represents an alternative to the well-known palladium-catalyzed coupling reactions.

Heteroleptic silver(I) complexes have recently started to attract attention in thin-film lighting technologies as an alternative to copper(I) analogues due to the lack of flattening distortion upon excitation. However, the interpretation of their photophysical behavior is challenging going from traditional fluorescence/phosphorescence to a temperature-dependent dual emission mechanism and ligand-lock assisted thermally activated delayed fluorescence. Herein, we unveil the photoluminescence behavior of a three-coordinated Ag(I) complex with the N-heterocyclic carbene (NHC) ligand and 2,2'-bipyridine (bpy) as the N^N ligand. In contrast to its low-emissive Cu(I) complex structural analogues, a strong greenish emission was attributed to the presence of aggregates formed by π-π intermolecular interactions as revealed by the X-ray structure and aggregation induced emission (AIE) studies in solution. In addition, the temperature-dependent time-resolved spectroscopic and computational studies demonstrated that the emission mechanism is related to a phosphorescence emission mechanism of two very close lying (Δ E = 0.08 eV) excited triplet states, exhibiting a similar delocalized nature over the bipyridine ligands. Unfortunately, this favourable AIE is lost upon forming homogeneous thin films suitable for lighting devices. Though the films showed very poor emission, the electrochemical stability under device operation conditions is remarkable compared to the prior-art, highlighting the potential of [Ag(NHC)(N^N)][X] complexes in thin-film lighting.

Regioselective phosphonation of pyridines is an interesting transformation in synthesis and medicinal chemistry. We report herein a metal-free approach enabling access to various 4-phosphonated pyridines. The method consists of simply activating the pyridine ring with a Lewis acid (BF 3 ·OEt 2 ) to facilitate the nucleophilic addition of a phosphine oxide anion. The formed sigma complex is subsequently oxidized with an organic oxidant (chloranil) to yield the desired adducts in good to excellent yields. We furthermore showed that access to C2-phosphoinated pyridines can be achieved in certain cases with strong Lewis basic phosphorus nucleophiles or with strong Lewis acidic pyridines. Both experimental and computational mechanistic investigations were undertaken and allowed us to understand the factors controlling the reactivity and selectivity of this reaction., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

An efficient diastereoselective route is developed to get access to novel spiropyrrolo[1,2- a ]isoquinoline-oxindole skeletons by a one-pot three -component [3 + 2] cycloaddition reaction of ( Z )-5-arylidene-1,3-thiazolidine-2,4-diones, isatin derivatives, and 1,2,3,4-tetrahydroisoquinoline (THIQ). Interestingly, the regioselectivity of the reaction is both temperature- and solvent-dependent, allowing the synthesis of two regioisomeric endo -dispiropyrrolo[2,1- a ]isoquinolineoxindoles in excellent yield. Unprecedentedly, each isomeric dispiropyrrolo[2,1- a ]isoquinolineoxindole endured retro- 1,3-dipolar cycloaddition/recycloaddition reactions under thermal or catalytic conditions to regenerate the corresponding regioisomeric counterpart. In addition, DFT calculations were performed at the M062X/6-31++g(d,p) level of theory to unravel the origin of the reversal of regioselectivity and endo- stereoselectivity of the title 1,3-dipolar cycloaddition reactions. Upon treatment of Isatin, THIQ with ( Z )-4-arylidene-5-thioxo-thiazolidin-2-ones as dipolarophiles, unusual rhodanine analogues were formed, along with smaller amounts of a dispirooxindole-piperazine. The structure and the relative configuration of these N- heterocycles were unambiguously assigned by spectroscopic techniques and confirmed by four single-crystal structures. In vitro and in vivo studies reveal that the novel rhodanine derivatives exert antidiabetic activity. The binding affinity with the active site of the enzyme α-amylase was studied by molecular docking. Furthermore, the bioavailability assessed through virtual ADME parameters (Absorption, Distribution, Metabolism, Elimination pharmacokinetics) and the excellent fit with the Lipinski and Veber rules predict good drug-likeness properties for a bromo-substituted 2-sulfanylidene-1,3-thiazolidin-4-one.

The synthesis and characterization of a family of copper(i) complexes bearing a bridged bis-pyridyl ancillary ligand is reported, highlighting how the bridge nature impacts the photo- and electro-luminescent behaviours within the family. In particular, the phosphonium bridge led to copper(i) complexes featuring good electrochemical stability and high ionic conductivity, as well as a stark blue-to-orange luminescence shift compared to the others. This resulted in high performance light-emitting electrochemical cells reaching stabilities of 10 mJ at ca. 40 cd m -2 that are one order of magnitude higher than those of the other complexes. Overall, this work sheds light onto the crucial role of the bridge nature of the bis-pyridyl ancillary ligand on the photophysical features, film forming and, in turn, on the final device performances.

2-N-aminoquinazolines were prepared by consecutive S N Ar functionalization. X-ray structures display the nitrogen lone pair of the 2-N-morpholino group in conjugation with the electron deficient quinazoline core and thus representing electronic push-pull systems. 2-N-aminoquinazolines show a positive solvatochromism and are fluorescent in solution and in solid state with quantum yields up to 0.73. Increase in electron donor strength of the 2-amino substituent causes a red-shift of the intramolecular charge transfer (ICT) band (300-400 nm); whereas the photoluminescence emission maxima (350-450 nm) is also red-shifted significantly along with an enhancement in photoluminescence efficiency. HOMO-LUMO energies were estimated by a combination of electrochemical and photophysical methods and correlate well to those obtained by computational methods. ICT properties are theoretically attributed to an excitation to Rydberg-MO in SAC-CI method, which can be interpreted as n-π* excitation. 7-Amino-2-N-morpholino-4-methoxyquinazoline responds to acidic conditions with significant increases in photoluminescence intensity revealing a new turn-on/off fluorescence probe., (© 2021 Wiley-VCH GmbH.)

An expeditious route to planar chiral sulfur-based scaffolds has been achieved in two operational steps from cheap and commercial [2.2]paracyclophane hydrocarbon. The sulfur atom was introduced in a specific benzylic position of the [2.2]paracyclophane according to a reductive sulfanylation reaction, which proceeds under two complementary reaction conditions with either the BF 3 ·OEt 2 /Et 3 SiH or TFA/BH 3 ·THF combinations. The study was completed by the development of a highly efficient resolution approach by HPLC.

Four new metallophosphonates M(H 2 O)(PO 3 C 10 H 6 OH)·(H 2 O) 0.5 (M = Mn, Co, Cu, Zn) were obtained as single crystal and polycrystalline powders by hydrothermal synthesis from the precursors 6-hydroxy-2-naphthylphosphonic acid and the corresponding metal salts. These analogous hybrids crystalized in the space group P12 1 /c1 in a lamellar structure. Their layered structures consisted of inorganic [M(H 2 O)(PO 3 C)] layers stacked with organic bilayers of 6-hydroxy-2-naphthyl moieties "HO-C 10 H 6 " and free water molecules. Their structures were determined by single crystal X-ray diffraction and confirmed by powder X-ray diffraction and Le Bail refinement for the powder sample. The removal of water upon heating at 250 °C was studied by thermogravimetric analysis and temperature-dependent powder X-ray diffraction. Their magnetic properties were studied by SQUID magnetometry and show antiferromagnetic behavior for the Co analogue and the occurrence of a canted antiferromagnetic order at T N = 12.2 K for the Mn analogue. The Cu compound displayed an unprecedented ferromagnetic behavior. Their absorption and luminescence properties were investigated and revealed that the ligand and the compounds displayed a common behavior below a wavelength of 400 nm. Specific absorption bands were found in the compounds with Co 2+ and Cu 2+ at 539 nm and 849 nm, respectively. Moreover, particular luminescence bands were found for the compounds with Mn 2+ , Co 2+ and Zn 2+ at 598 nm, 551 nm and 530 and 611 nm, respectively.

A series of iodinated ligands for the SPECT imaging of 5-HT 4 receptors was designed starting from the previously reported hit MR-26132. We focused on the modulation of the piperidine-containing lateral chain by introducing hydrophilic groups in order to decrease the liphophilicity of the new ligands. All the synthesized compounds were tested for their binding affinities on 5-HT 4 Rs and based on the Ligand Lipophilicity Efficiency approach, compound 13 was further selected for radioiodination with iodine-125 and imaging experiments. Compound 13 showed its ability to displace the specific signal of the reference compound [ 125 I]SB-207710 but no significant detection of [ 125 I]13 was observed in vivo in SPECT experiments., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

A transition-metal frustrated Lewis pair approach has been envisaged to enhance the catalytic activity of tricarbonyl phosphine-free iron complexes in reduction of amines. A new cyclopentadienyl iron(II) tricarbonyl complex has been isolated, fully characterized, and applied in hydrogenation. This phosphine-free iron complex is the first Earth-abundant metal complex that is able to catalyze chemoselective reductive alkylation of various functionalized amines with functionalized aldehydes. Such selectivity and functionality tolerance (alkenes, esters, ketones, acetals, unprotected hydroxyl groups, and phosphines) have been demonstrated also for the first time at room temperature with an Earth-abundant metal complex. This alkylation reaction was also performed without any preliminary condensation and generated only water as a byproduct. The resulting amines provided rapid access to potential building blocks, metal ligands, or drugs. Density functional theory calculations highlighted first that the formation of the 16 electron species, via the activation of the tricarbonyl complex Fe3, was facilitated and, second, that the hydrogen cleavage did not follow the same pathway as bond breaking, usually described with the known cyclopentadienone iron tricarbonyl complexes (Fe1 and Fe4). These calculations highlighted that the new complex Fe3 does not behave as a bifunctional catalyst, in contrast to its former congeners.

Unambiguously confirmed by low-temperature in situ NMR experiments, X-ray diffraction and vibrational spectroscopy, phosphonium-carbenium superelectrophiles are shown to be generated in strong acidic conditions. Representing crucial intermediates, their exploitation allows for the synthesis of unprecedented fluorinated (cyclic) phosphine oxides., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A general efficient one-pot synthesis of S-perfluoroalkylated NH-sulfoximines from sulfides has been developed using phenyliodine diacetate (PIDA) and ammonium carbamate. Remarkable rate enhancement with trifluoroethanol was observed, presumably due to H-bonding effects. These mild and metal-free conditions are compatible with -CH 2 F, -CFCl 2 , -CF 2 H, -CF 2 Br, -C 4 F 9 , and -CF 3 groups, in both the alkyl- and aryl series. Based on a 19 F NMR analysis, a λ 6 -acetoxysulfanenitrile intermediate was proposed., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Several hitherto unknown (E)-but-2-enyl nucleoside phosphonoamidate analogs (ANPs) were prepared directed with nitrogen reagents by cross-metathesis in water-under ultrasound irradiation. Two diastereoisomers were formally identified by X-ray diffraction. These compounds were evaluated against a large spectrum of DNA and RNA viruses. Among them, the phosphonoamidate thymine analogue 19 emerged as the best prodrug against varicella-zoster virus (VZV) with EC 50 values of 0.33 and 0.39 μM for wild-type and thymidine kinase deficient strains, respectively, and a selectivity index ≥200 μM. This breakthrough approach paves the way for new purine and pyrimidine (E)-but-2-enyl phosphonoamidate analogs., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

We report on the benefits of changing the bridging group X of bis-pyridyl ligands, that is, Py-X-Py where X is NH, CH 2 , C(CH 3 ) 2 , or PPh, on the photo- and electroluminescent properties of a new family of luminescent cationic H-heterocyclic carbene (NHC) copper(I) complexes. A joint experimental and theoretical study demonstrates that the bridging group affects the molecular conformation from a planar-like structure (X is NH and CH 2 ) to a boat-like structure (X is C(CH 3 ) 2 and PPh), leading to i) four-fold enhancement of the photoluminescence quantum yield (ϕ em ) without affecting the thermally activated delayed fluorescence mechanism, and ii) one order of magnitude reduction of the ionic conductivity (σ) of thin films. This leads to an overall enhancement of the device efficacy and luminance owing to the increased ϕ em and the use of low applied driving currents., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report a new procedure for the preparation of NH-sulfoximines from sulfides using PIDA as an oxidant and ammonium carbamate as the ammonia source. Excellent yields were obtained with a wide range of sulfides. The formation of acetoxy- and methoxy-λ 6 -sulfanenitrile as intermediates was proposed, both of which were converted to the NH-sulfoximine by the action of the solvent. The structure of these intermediates was confirmed by 1 H, 13 C and 15 N NMR and HRMS analysis.

This work describes the first transition metal-free stereospecific synthesis of (E)-(1-fluoro-2-arylvinyl)phosphine boranes through the addition of diarylphosphine-boranes to gem-bromofluoroalkenes in the presence of a base at room temperature. The reaction proceeds well under very mild conditions and tolerates a variety of functionalities. Scope and limitations of the reaction are discussed. Mechanistic investigations have been undertaken and revealed that the reaction takes place through an S RN 1 mechanism. The formation of the fluorinated vinyl radical has been evidenced by electron paramagnetic resonance (EPR) experiment.

A novel and efficient method for the generation of phosphinoyl radicals from the combination of diphenyliodonium salt (Ph 2 I + , - OTf) with triethylamine (Et 3 N) in the presence of secondary phosphine oxides is reported. By employing this practical and simple approach, a large variety of 6-phosphorylated phenanthridines have been synthesized through the addition of phosphinoyl radicals to isonitriles as radical acceptors. The reaction works smoothly in the absence of any transition metal or photocatalyst. On the basis of electron paramagnetic resonance (EPR) and density functional theory (DFT) calculations, the mechanism of this reaction is discussed.

Study of the intramolecular aza-Michael addition reaction from an aminofluorovinylsulfone opens a new route for the synthesis of pyrrolidine derivatives. An unexpected diastereoselective cyclization reaction was observed, leading preferentially to the anti-N-benzylpyrrolidine sulfone. The resulting sulfone was reacted with aldehydes to access β-substituted α-fluoroalkenyl pyrrolidines in one step.

This study presents the influence of various substituents on the photophysical features of heteroleptic copper(I) complexes bearing both N-heterocyclic carbene (NHC) and dipyridylamine (dpa = dipyridylamine skeleton corresponding to ligand L1) ligands. The luminescent properties have been compared to our recently reported archetypal blue emitting [Cu(IPr)(dpa)][PF6] complex. The choice of the substituents on both ligands has been guided to explore the effect of the electron donor/acceptor and "push-pull" on the emission wavelengths and photoluminescence quantum yields. A selection of the best candidates in terms of their photophysical features were applied for developing the first blue light-emitting electrochemical cells (LECs) based on copper(I) complexes. The device analysis suggests that the main concern is the moderate redox stability of the complexes under high applied driving currents, leading to devices with moderate stabilities pointing to a proof-of-concept for further development. Nevertheless, under low applied driving currents the blue emission is stable, showing performance levels competitive to those reported for blue LECs based on iridium(III) complexes. Overall, this work provides valuable guidelines to tackle the design of enhanced NHC copper complexes for lighting applications in the near future.

Highly functionalized benzo[b]phosphole oxides were synthesized from reactions of arylphosphine oxides with alkynes under photocatalytic conditions by using eosin Y as the catalyst and N-ethoxy-2-methylpyridinium tetrafluoroborate as the oxidant. The reaction works under mild conditions and has a broad substrate scope. Mechanistic investigations have been undertaken and revealed the formation of a ground state electron donor-acceptor complex (EDA) between eosin (the photocatalyst) and the pyridinium salt (the oxidation agent). This complex, which has been fully characterized both in the solid state and in solution, turned out to exhibit a dual role, i.e., the oxidation of the photocatalyst and the formation of the initiating radicals, which undergoes an intramolecular reaction avoiding the classical diffusion between the two reactants. The involvement of ethoxy and phosphinoyl radicals in the photoreaction has unequivocally been evidenced by EPR spectroscopy.

A step-economic and metal-catalyst-free synthesis of 2-(tosylamido)- and 2,5-bis(tosylamido)-thiophenes from nonsymmetrical 1,3-butadiynamides and symmetrical 1,3-butadiyne-1,4-diamides is reported. The reaction proceeds in the presence of Na2S·9H2O (2-3 equiv) under mild reaction conditions (50 °C) and is facilitated by polarized carbon-carbon triple bonds in ynamides. This new approach to thiophenes based on the chemistry of ynamides was applied to the synthesis of a bis(tosylamido)-capped terthiophene having a string of N,S-heteroatoms embedded in a highly π-conjugated molecular frame.

Acyl chloride of N-phthaloyl-(S)-isoleucine is an efficient chiral auxiliary for the resolution of (±)-[2.2]paracyclophane-4-thiol. A preparative protocol, based on the conversion into diastereoisomeric thiolesters and separation by two fractional crystallizations and column chromatography, was developed. Deprotection with LiAlH4 allowed isolation of the individual thiol enantiomers in good yield (∼40%) and high enantiomeric purity (ee >93%). The absolute configurations were determined by comparison of the optical rotation value of the products with literature data and were confirmed by X-ray crystallography.

We describe the synthesis of new cationic tricoordinated copper complexes bearing bidentate pyridine-type ligands and N-heterocyclic carbene as ancillary ligands. These cationic copper complexes were fully characterized by NMR, electrochemistry, X-ray analysis, and photophysical studies in different environments. Density functional theory calculations were also undertaken to rationalize the assignment of the electronic structure and the photophysical properties. These tricoordinated cationic copper complexes possess a stabilizing CH-π interaction leading to high stability in both solid and liquid states. In addition, these copper complexes, bearing dipyridylamine ligands having a central nitrogen atom as potential anchoring point, exhibit very interesting luminescent properties that render them potential candidates for organic light-emitting diode applications.

A versatile synthesis of 1,2,3-triazolyl-4-phosphines from the borane complexes of phosphino-alkynes is reported. The efficiency of the procedure relies on the use of readily available silyl-protected alkynylphosphine-boranes, which were subjected to desilylation with TBAF followed by copper-catalyzed azide-alkyne-cycloaddition in one pot. Subsequent treatment with DABCO afforded the targeted triazolylphosphines in high yields. The reported method was applied to the synthesis of the first example of an enantioenriched P-stereogenic triazolylphosphine (98.8% ee).

Reductive amination under hydrogen pressure is a valuable process in organic chemistry to access amine derivatives from aldehydes or ketones. Knölker's complex has been shown to be an efficient iron catalyst in this reaction. To determine the influence of the substituents on the cyclopentadienone ancillary ligand, a series of modified Knölker's complexes was synthesised and fully characterised. These complexes were also transformed into their analogous acetonitrile iron-dicarbonyl complexes. Catalytic activities of these complexes were evaluated and compared in a model reaction. The scope of this reaction is also reported. For mechanistic insights, deuterium-labelling experiments and DFT calculations were undertaken and are also presented., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A new asymmetric three-component domino process, based on a diastereoselective hetero-Diels-Alder reaction, involving an aldehyde, an alkene, and a chiral thiocarbamate was developed. The chiral auxiliary is directly removed during this process, leading to enantioenriched 2H-1,3-thiazin-2-ones with up to 96% ee.

A series of novel 5-benzylated 4-oxo-3,4-dihydro-5H-pyridazino[4,5-b]indoles was synthesized through a newly developed approach. All these compounds were evaluated against DYRK1A, CDK5 and PI3Kα and showed promising inhibitory activities against PI3Kα with most IC(50) values in the micromolar range. Among them, compound 18 was strongly considered as the most interesting compound with an IC(50) value of 0.091 μM. This series exhibited also significant anti-proliferative effects in various human cancer cell lines including those resulting in activation of the PI3K pathway., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

Copper-phosphido-borane complexes were synthesized and isolated for the first time. Their structures were experimentally and computationally investigated. They were shown to display catalytic activity in C(sp)-P bond formation., (This journal is © The Royal Society of Chemistry 2012)

Protein-protein interactions are central to many biological processes, from intracellular communication to cytoskeleton assembly, and therefore represent an important class of targets for new therapeutics. The most common secondary structure in natural proteins is an α-helix. Small molecules seem to be attractive candidates for stabilizing or disrupting protein-protein interactions based on α-helices. In our study, we assessed the ability of oligopyridyl scaffolds to mimic the α-helical twist. The theoretical as well as experimental studies (X-ray diffraction and NMR) on conformations of bipyridines in the function of substituent and pyridine nitrogen positions were carried out. Furthermore, the experimental techniques showed that the conformations observed in bipyridines are maintained within a longer oligopyridyl scaffold (quaterpyridines). The alignment of the synthesized quaterpyridine with two methyl substituents showed that it is an α-helix foldamer; their methyl groups overlap very well with side chain positions, i and i + 3, of an ideal α-helix.

Preliminary results concerning a conceptually novel route to chiral sulfoxides based on the asymmetric alkylation of sulfenate salts with alkyl halides mediated by a chiral phase-transfer catalyst are described. As a representative example, o-anisyl methyl sulfoxide was produced in 96% yield and with an enantiomeric excess of 58% using commercial cinchonidinium derivative 2a., (© 2011 American Chemical Society)

A multinuclear NMR study shows that the deprotonation of diphenylphosphine-borane by n-BuLi in THF leads to a disolvated lithium phosphido-borane Ph(2)P(BH(3))Li of which Li(+) is connected to the hydrides on the boron and two THF molecules rather than to the phosphorus. This entity behaves as both a phosphination and a reducing agent, depending on the kinetic or thermodynamic control imposed to the reaction medium. Density functional theory computations show that H(2)P(BH(3))Li exhibits a ditopic character (the lithium cation can be in the vicinity of the hydride or of the phosphorus). It explains its dual reactivity (H- or P-addition), both routes going through somewhat similar six-membered transition states with low activation barriers.

The title compound, C(19)H(20)BrNO(2), consists of a carbazole skeleton with methyl groups at positions 1 and 4, a protecting group located at the N atom and a Br atom at position 6. The pyrrole ring is oriented at dihedral angles of 1.27 (7) and 4.86 (7)° with respect to the adjacent benzene rings. The dihedral angle between the benzene rings is 5.11 (7). The crystal structure is determined mainly by intra-molecular C-H⋯O and inter-molecular π-π inter-actions. π-stacking between adjacent molecules forms columns with a parallel arrangement of the carbazole ring systems. The presence of the tert-but-oxy-carbonyl group on the carbazole N atom and the intra-molecular hydrogen bond induce a particular conformation of the exocyclic N-C bond within the mol-ecule.

A one-pot synthesis of various N-substituted 3-amino-thiochromanes from 4-benzyl-2-methyl thiazoline via a thiazolinium salt is described. The obtained 3-amino-thiochromanes are enantiopure, as their precursors derive from chiral 2-aminoalcohols. The reaction involves the formation of a disulfide, which subsequently takes part in an unprecedented intramolecular electrophilic aromatic substitution.

A series of substituted aryl malonamates have been prepared. These compounds are analogues of aryl phenaceturates where the amido side chain has been replaced by a retro-amide. Like the phenaceturates, these compounds are substrates of typical class A and class C beta-lactamases, particularly of the latter, and of soluble DD-peptidases. The effect of substituents alpha to the ester carbonyl group on turnover by these enzymes is similar to that in the phenaceturates. On the other hand, N-alkylation of the side chain amide of malonamates, but not of phenaceturates, retains the susceptibility of the compounds to hydrolysis by beta-lactamases. This reactivity is not enhanced, however, by bridging the amide nitrogen and Calpha atoms. A phosphonate analogue of the malonamates was found to be an irreversible inhibitor of the beta-lactamases. These results, therefore, provide further evidence for the covalent access of compounds bearing retro-amide side chains to the active sites of beta-lactam-recognizing enzymes., (Copyright (c) 2009 Elsevier Ltd. All rights reserved.)

The title compound, C(9)H(14)BNO(2)S, is in an unusual bend conformation and the B atom of one mol-ecule within the crystal forms an inter-molecular dative bond with the N atom of a neighbouring mol-ecule, an infrequent phenomenon in boronic derivative crystals.

An efficient synthesis of enantiopure 1,3-benzothiazines has been achieved by reaction of cyclic sulfenamides and alkylpropiolate or tosylacetylene catalyzed by cesium fluoride.

The stilbene derivative 1,2,3-trimethoxy-4-[(E)-2-phenylvinyl]benzene, C(17)H(18)O(3), (I), and its homocoupling co-product (E,E)-1,4-bis(2,3,4-trimethoxyphenyl)buta-1,3-diene, C(22)H(26)O(6), (II), both have double bonds in trans conformations in their conjugated linkages. In the structure of stilbene (I), the aromatic rings deviate significantly from coplanarity, in contrast with coproduct (II), the core of which is rigorously planar. The deviation in stilbene (I) seems to be driven by intermolecular electrostatic interactions. Diene (II) sits on a crystallographic inversion centre, which bisects the conjugated linkage.

A new methodology, using fluoride ion as a nucleophilic catalyst, was applied for the synthesis of enantiopure 1,4-benzothiazepine from cyclic sulfenamide and electron-deficient acetylene, with high efficiency and atom economy.

In the closely related quinoline compounds 8-nitro-2-(trichloromethyl)quinoline, (I), 6-nitro-2-(trichloromethyl)quinoline, (II), and 5-nitro-2-(trichloromethyl)quinoline, (III), all C(10)H(5)Cl(3)N(2)O(2), which are of both reactivity and pharmacological interest, and for which the biological activity and cytotoxicity appear to be based on the positions of the CCl(3) and nitro substituents, the nitro group is only coplanar with its aromatic substrate in (II). The deviation of the nitro group from coplanarity is concluded to be a function of both its position with respect to the trichloromethyl group and the intermolecular contacts in which it participates. The discrepancies between the crystal structures and the molecular shapes predicted by ab initio calculations are also explained in these terms. The quinoline ring is not rigorously planar in any of the structures, which may be explained by stress produced by the CCl(3) substituent.

The title carbazolyl boronic ester, C(22)H(28)BNO(2), (I), is a building block for the synthesis of new carbazole derivatives of potential utility as pharmaceutically active compounds. The crystal structure of (I) and of the title bromocarbazole compound, C(16)H(16)BrN, (II), the synthetic precursor of (I), were solved and analysed with the aim of understanding the lack of reactivity of (I) under Suzuki cross-coupling reaction conditions. In both structures, the methyl groups are coplanar with the carbazole ring system, and the ethyl group lies out of the carbazole plane. The dioxaborolane ring of boronic ester (I) adopts a half-chair conformation but lies approximately in a planar orientation with respect of the carbazole ring system, whereas the Br atom of (II) is coplanar with the carbazole plane. In (I), the carbazole-boronic ester C-B bond length is 1.5435 (14) A, which is somewhat shorter than the usual value of 1.57 A.

A straightforward and high-yielding access to various [2.2]paracyclophanes possessing a sulfur-based functional group is reported, the key step being a SEAr reaction mediated by a sulfonium salt. The versatility of the methodology was exemplified by an original application in sulfenate salt chemistry, from which a remarkable chirality transfer was observed.

Ethane-1,1,2-trisphosphonic acid crystallizes as a hemihydrate, C(2)H(9)O(9)P(3).0.5H(2)O, in which the water O atom lies on an inversion centre in the space group P2(1)/c. The acid component, which contains a short but noncentred O-H...O hydrogen bond, adopts a gauche conformation. The acid components are linked by an extensive series of O-H...O hydrogen bonds to form layers, which are linked into pairs by the water molecules.

A useful synthesis of rare 1,2-disubstituted ferrocenylalkyl amines with (S(Fc),S) configuration has been achieved in a sequential one-pot methodology from (S)-p-tolylsulfinylferrocene.

The crystal structures of closely related quinoline compounds substituted at the 2-position by a vinyl group, either including a Cl atom [2-(1-chloro-2-methylprop-1-enyl)-8-nitroquinoline, C(13)H(11)ClN(2)O(2), (I)] or not [2-(2-methylprop-1-enyl)-8-nitroquinoline, C(13)H(12)N(2)O(2), (II)], show an important deviation of the vinyl group from coplanarity with the quinoline ring system if the Cl atom is present. The nitro group is perpendicular [in (II)] or nearly so [in (I)] to the quinoline ring system. In (II), all non-H atoms except the nitro O atoms are located on a crystallographic mirror plane.

[reaction: see text] The in situ preparation of a sulfonium ylide reagent achieved the highly diastereoselective epoxidation of isatins, so that a new and straightforward access to biologically significant spiro-epoxyoxindoles is provided. The first investigations of an asymmetric version are reported with enantiopure sulfides.

Vinylphosphine-borane complexes are easily synthesized by palladium-catalyzed C-P cross-coupling of vinyl triflates with secondary phosphine-boranes. This method allows the synthesis of phosphine derivatives not always easily accessible by other approaches. The vinylphosphine derivatives are purified by chromatography on silica gel. The versatility of the method is proved by using various triflates and diaryl-, dialkyl- and alkylarylphosphine-borane precursors. Chiral enantiopure phosphine-boranes are synthesized from chiral triflates.