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A green and efficient protocol was developed for the one-pot three-component synthesis of novel 2-(4-hydroxy-2-oxo-2H-chromen-3-yl)-2-(arylamino)-1H-indene-1,3(2H)-dione derivatives by the reaction of 4-hydroxycoumarin, ninhydrin and aromatic amines in the presence of guanidine hydrochloride as an organocatalyst under solvent-free conditions. The present approach offers several advantages such as low cost, simple work-up, short reaction times, chromatography-free purification, high yields and greener conditions.

Transition-metal indenyl complexes usually exhibit different reactivity compared with their cyclopentadienyl analogues. Up to now, at least 10 metal-indenyl bonding modes have been reported. Because of the “indenyl effect”, transition-metal indenyl complexes usually display elevated reactivity in substitution and related reactions. This review provides an overview on the use and impact of indenyl phosphines in the organometallic chemistry and transition-metal-catalysed reactions in recent two decades. Some cationic and zwitterionic metal complexes supported by P,N-substituted indene or indenide ligands are descibed. They have been reported to induce the cleavage of the E–H (E = H, Si and B) bonds and could be used as catalysts for addition of E–H bonds to unsaturated substrates. Moreover, 2-aryl indenyl phosphine ligands L3-L12 have proven to be a class of versatile ligands for palladium-catalysed C–C and C–N cross-coupling reactions.

Indene (IND) is a kind of important aromatic hydrocarbon that is extracted from coal tar and has important applications in industry and biology. In the process of production and utilization, it is easy to enter the soil and produce toxic effects on the soil or organisms. The earthworm is an important organism in the soil. The toxicity of indene on earthworm coelomocytes is rarely studied, and the oxidative stress effects of IND on earthworm coelomocytes remain unclear. In this study, coelomocytes from earthworms and antioxidant enzymes were selected as the research targets. In addition, IND caused oxidative stress, and its related toxic effects and mechanisms were systematically studied and evaluated at the cellular and molecular levels. The results showed that IND destroyed the redox balance in earthworm coelomocytes, and the large accumulation of reactive oxygen species (ROS) significantly inhibited the activities of the antioxidant system, including superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH), and caused lipid peroxidation and membrane permeability changes, resulting in a decrease in cell viability to 74.5% of the control group. At the molecular level, IND was bound to SOD by the arene-H bond, and the binding constant was 4.95 × 103. IND changed the secondary structure of the SOD and led to a loosening of the structure of the SOD peptide chain. Meanwhile, IND caused SOD fluorescence sensitization, and molecular simulation showed that IND was mainly bound to the junction of SOD subunits. We hypothesized that the changes in SOD structure led to the increase in SOD activity. This research can provide a scientific basis for IND toxicity evaluation.

Catalytic enantioselective epoxidation of olefins plays an important role in the production of optically-active epoxy. Transition-metal complexes prove efficient for the catalytic epoxidation of un-functionalized olefins by employing privileged chiral ligands with rotational symmetry and bulky substituents, which usually require complicated multistep synthesis and are often very expensive. Here, this work proposes an efficient strategy to promote the enantioselectivity of Mn(III)-catalyzed indene epoxidation, which simply utilizes the nanosheets of layered double hydroxides (LDHs) to modify α-amino acid derivatives as chiral ligands, achieving an enantioselectivity of more than 91.0%, much higher than that (

A highly regioselective divergent approach for the phosphine-containing indane/indene derivatives from the ene-yne-oxazolone precursors was reported. An insight into the reaction mechanism involving the phospha-1,4-addition followed by 5-exo-dig ring closure with a concomitant C-P/C-C bond formation was also proposed. This promising protocol utilized H-phosphonate as the phosphonating reagent in a silver-catalyzed or base-mediated cascade cyclization to construct the corresponding phosphorylated spiroindenoxazolones and amidoindenes, respectively, in good yields (up to 88% yield).

Structurally important benzobicyclo[3.3.1]nonane derivatives were synthesized by a gallium trichloride mediated reaction of readily available donor-acceptor cyclopropanes (DACs) with 1,3-dienes as a one-pot cascade ionic [2 + 4]-cycloaddition/Friedel-Crafts-type cyclization process. At the first stage, DACs act as sources of formal gallium 1,2-zwitterionic complexes to give 6-benzylcyclohex-3-ene-1,1-dicarboxylates that are converted under certain conditions in the presence of GaCl3 to give benzobicyclo[3.3.1]nonanes in 30-74% yields. The process is tolerant of varying substituents at different positions of the main framework. Further, potentially useful modifications of benzobicyclo[3.3.1]nonane derivatives are demonstrated. 2-Cyclopropylbutadiene reacts with DAC at higher temperature more deeply with cleavage of three-membered rings in both cyclopropane substrates, and twofold alkylation of the Ph-substituent at ortho- and meta-positions, that leads to a 1,2,7,8,9,10-hexahydro-6H-7,10a-methanocycloocta[cd]indene skeleton. Cyclopropane-1,1-diesters containing a bulky substituent in the ester group react with isoprene in a different way to give bicyclic lactones containing a 2-oxabicyclo[2.2.2]octan-3-one moiety.

Isomers of C11H8 have been theoretically examined using density functional theory and coupled-cluster methods. The current investigation reveals that 2aH-cyclopenta[cd]indene (2), 7-ethynyl-1H-indene (6), 4-ethynyl-1H-indene (7), 6-ethynyl-1H-indene (8), 5-ethynyl-1H-indene (9), and 7bH-cyclopenta[cd]indene (10) remain elusive till date in the laboratory. The puckered low-lying isomer 2 lies at 9 kJ mol-1 below the experimentally known molecule, cyclobuta[de]naphthalene (3), at the fc-CCSD(T)/cc-pVTZ//fc-CCSD(T)/cc-pVDZ level of theory. 2 lies at 36 kJ mol-1 above the thermodynamically most stable and experimentally known isomer, 1H-cyclopenta[cd]indene (1), at the same level. It is identified that 1,2-H transfer from 1 yields 2H-cyclopenta[cd]indene (14) and subsequent 1,2-H shift from 14 yields 2. Appropriate transition states have been identified, and intrinsic reaction coordinate calculations have been carried out at the B3LYP/6-311+G(d,p) level of theory. Recently, 1-ethynyl-1H-indene (11) has been detected using synchrotron-based vacuum ultraviolet ionization mass spectrometry. 2-Ethynyl-1H-indene (4) and 3-ethynyl-1H-indene (5) have been synthetically characterized in the past. While the derivatives of 7bH-cyclopenta[cd]indene (10) have been isolated elsewhere, the parent compound remains unidentified till date in the laboratory. Although C11H8 is a key elemental composition of astronomical interest for the formation of polycyclic aromatic hydrocarbons in the interstellar medium, none of its low-lying isomers have been characterized by rotational spectroscopy though they are having a permanent dipole moment (μ ≠ 0). Therefore, energetic and spectroscopic properties have been computed, and the present investigation necessitates new synthetic studies on C11H8, in particular 2, 6-10, and also rotational spectroscopic studies on all low-lying isomers.

A Cu-catalyzed cascade reaction between N-alkoxyanilines having an electron-donating functional group at the ortho position and dienophiles, such as N-methylmaleimide, styrene, and indene, proceeded via a dearomative [1,3]-alkoxy rearrangement followed by the Diels-Alder reaction, affording the corresponding ketimines with highly functionalized bicyclic skeletons in an efficient and stereoselective manner. Our mechanistic investigations indicated that the [1,3]-rearrangement is the rate-determining process, efficiently suppressing unfavorable side reactions.

Quantum chemistry and statistical reaction rate theory calculations have been performed to investigate the products and kinetics of indenyl radical decomposition. Three competitive product sets are identified, including formation of a cyclopentadienyl radical (c-C5H5) and diacetylene (C4H2), which has not been included in prior theoretical kinetics investigations. Rate coefficients for indenyl decomposition are determined from master equation simulations at 1800-2400 K and 0.01-100 atm, and temperature- and pressure-dependent rate coefficient expressions are incorporated into a detailed chemical kinetic model for indene pyrolysis. Indenyl is found to predominantly decompose to o-benzyne (o-C6H4) + propargyl (C3H3), with lesser amounts of fulvenallenyl (C7H5) + C2H2 and c-C5H5 + C4H2.

p-TsOH catalyzed Diels-Alder reaction of 3-(indol-3-yl)maleimides with 3-phenacylideneoxindoles in toluene at 80 °C for two hours afforded cis/trans isomers of 3a',4′,6′,10c'-tetrahydrospiro[indoline-3,5′-pyrrolo[3,4-c]carbazoles] in nearly comparable yields, which could be easily converted to the corresponding 4′,6′-dihydrospiro[indoline-3,5′-pyrrolo[3,4-c]carbazole] in high yields and with high diastereoselectivity by further DDQ oxidation. Additionally, the similar reaction of 3-(indol-3-yl)maleimides with 2-arylidene-1,3-indanediones in toluene 80 °C and sequential DDQ oxidation afforded functionalized dihydrospiro[indene-2,5′-pyrrolo[3,4-c]carbazoles] as major products.

Multiple hydrogen bonds containing nucleophilic phosphines derived from dipeptide dual-reagents catalyzed asymmetric Michael addition reactions between indene esters and activated olefins in high yields and good to excellent enantioselectivities under mild reaction conditions. The success of current highly selective reactions should provide inspiration for expansion to other reactions and would open up new paradigms for the synthesis of indanone derivatives bearing chiral quaternary carbon centers.

Nature-inspired, bridged polycyclic molecules share low similarity with currently available drugs, containing preferentially planar and/or achiral moieties. This "Escape from Flatland" scenario, aimed at exploring pharmacological properties of atypical molecular scaffolds, finds interest in synthetic routes leading to tridimensional-shaped molecules. Herein we report on the synthesis of N-bridged cyclopenta[a]indene derivatives, achieved through microwave-assisted thermal rearrangement of allene 3-benzazecines with high diastereoselectivity. The biological evaluation disclosed selective inhibition of human acetylcholinesterase or butyrylcholinesterase, depending on the substitution around the molecular core, which was rationalized by means of docking simulations. The most potent BChE inhibitor 31 was effective in neuroprotection from glutamatergic excitotoxicity and displayed low intrinsic cytotoxicity and good brain penetration. Overall, compound 31 and its close congeners 34 and 35 acted as multitarget agents addressing different biological events involved in neurodegeneration, particularly in the progression of Alzheimer's disease.

A gold(III)-catalyzed cascade oxidation/cyclization of alkylidenecyclopropane-tethered ynones for the assembly of diverse polycycles by employing different N-oxides with distinct nucleophilic properties is reported. This protocol enables the synthesis of cyclopentene-fused indenes and cyclobutane-fused naphthalenones in moderate to excellent yields using common starting materials in the presence of 2,6-Cl2-pyridine N-oxide as an indispensable co-ligand of the gold(III) catalyst and 8-Me-quinoline N-oxide as an oxidant, respectively. Notably, compound 3h showed promising antibacterial activity against R. solanacearum (MIC = 2 μg mL−1), and its preliminary antibacterial mechanism was also explored.

Studies into the Cp*Rh(iii)-catalysed hydroarylation of alkenes with aryl acyl silanes led to the discovery of a new synthetic strategy to access unique silicon derived indene frameworks. Rather than protodemetalation of the metal enolate formed following insertion of an alkene into the aryl C-H bond, intramolecular aldol condensation of the acyl silane occurred to generate a series of 2-formyl- and 2-acetyl-3-silyl indenes. This represents only the second example of rhodium-catalysed C-H functionalisation employing acyl silanes as weakly coordinating directing groups and the intramolecular aldol condensation strategy was extended to access analogous silicon derived benzofurans.

Resonance-stabilized radical chain (RSRC) reactions were recently proposed as alternative formation and growth pathways of polycyclic aromatic hydrocarbons (PAHs). In the present study, the growth of indene from the resonance-stabilized cyclopentadienyl radical following a series of RSRC sequences is investigated. Temperature- and pressure-dependent rate coefficients for acetylene addition reactions to the cyclopentadienyl, vinylcyclopentadienyl, cycloheptatrienyl, and benzyl radicals are determined based on high-level quantum chemistry and RRKM/master equation calculations. The acetylene addition to the resonance-stabilized cyclopentadienyl radical can generate resonance-stabilized vinylcyclopentadienyl, cycloheptatrienyl, and benzyl radicals. The formation reaction of cycloheptatrienyl has the highest rate constant compared to those of vinylcyclopentadienyl and benzyl. The acetylene addition to the above three resonance-stabilized C7H7 isomers forms indene. It is found that the indene formation reaction from C2H2 addition to benzyl has the highest rate constant, while that from C2H2 addition to cycloheptatrienyl is the lowest. The impacts of the investigated reactions on indene formation are then numerically explored in both counterflow diffusion and laminar premixed flame configurations. Results indicate that the RSRC pathways via C2H2 addition to vinylcyclopentadienyl and cycloheptatrienyl radicals have marginal contributions to indene formation.

The usage of earth-abundant, nontoxic transition metals in place of rare noble metals is a central goal in catalysis. This would be especially interesting when the reactivity and selectivity patterns can be tuned. Herein, we introduced the first Mn-catalyzed selective C-alkylation and olefination of fluorene, and indene with alcohols. Various substrates including benzylic, heteroaromatic, and aliphatic primary and secondary alcohols are employed as alkylating agents. Mechanistic investigations and a kinetic study underpin the involvement of the olefinated intermediate to furnish the alkylated product.

Rh(III)-Catalyzed efficient cascade annulation for the regioselective construction of various spiro-[imidazole-indene] derivatives has been reported by utilizing versatile propargyl alcohols as coupling partners. The type of propargyl alcohol plays a key role in tuning the combination state and controlling formation of different products.

Synergistic effect is one of the most important interactions between different fuel components and is very influential on combustion characteristics such as polycyclic aromatic hydrocarbon (PAH) and soot emissions, pyrolysis/oxidation reactivity and so on. In order to explore the potential synergistic effects between aromatics and open-chained fuels, pure toluene pyrolysis, pure acetylene pyrolysis and co-pyrolysis of toluene and acetylene were investigated in a flow reactor using synchrotron vacuum ultraviolet photoionization mass spectrometry at 1057–1340 K and 1 atm. Mole fractions of fuels and key products including both stable and reactive ones were evaluated. The experimental results indicate that in the co-pyrolysis of toluene and acetylene, the decomposition of both fuels is greatly stimulated and the formation of indene is significantly improved compared to the pyrolysis of pure toluene and pure acetylene. As a result, remarkable synergistic effects can be observed on pyrolysis reactivity and indene formation. A kinetic model for co-pyrolysis of toluene and acetylene was updated from our previous toluene model and was validated against the new data. The modeling analysis reveals that the unimolecular decomposition reaction of toluene producing benzyl radical and H atom is the chain-initiation reaction in both pure toluene pyrolysis and co-pyrolysis of toluene and acetylene. In the pure toluene pyrolysis, the self-combination reaction forming bibenzyl dominates the consumption of benzyl radical and results in strong chain termination. In the co-pyrolysis of toluene and acetylene, instead of the chain-termination reaction, a circulating reaction sequence initiating from the reaction between benzyl radical and acetylene continuously converts toluene and acetylene to indene and H2, which can explain the observed synergistic effects on pyrolysis reactivity and indene formation in the co-pyrolysis of toluene and acetylene.

This work reports an experimental and kinetic modeling investigation on the flow reactor pyrolysis of iso-butylbenzene and tert-butylbenzene at 0.04 and 1 atm. Pyrolysis products were detected and identified using synchrotron vacuum ultraviolet photoionization mass spectrometry, and their mole fractions versus heating temperature were measured. High-pressure-limit and pressure-dependent rate constants of unimolecular decomposition reactions of iso-butylbenzene were calculated in this work using the same method as the theoretical calculation investigation on similar reactions of n-butylbenzene, sec-butylbenzene and tert-butylbenzene reported by Belisario-Lara et al. [J. Phys. Chem. A, 122 (2018) 3980–4001]. Furthermore, a pyrolysis model of four butylbenzene isomers was developed from our previous models of n-butylbenzene and sec-butylbenzene and validated by the present experimental data. Modeling analysis was performed to reveal key pathways in fuel decomposition and polycyclic aromatic hydrocarbon (PAH) formation of iso-butylbenzene and tert-butylbenzene. The dominant decomposition reactions of iso-butylbenzene and tert-butylbenzene under pyrolysis conditions are benzylic C C bond dissociation reactions, while the major products in pyrolysis process are produced by β-scission reactions of primary radical products. Fuel-specific pathways are found to strongly affect the formation of PAHs, especially for indene, naphthalene and phenanthrene. Fuel isomeric effects on the pyrolysis of four butylbenzene isomers were also analyzed with special concerns on the fuel decomposition and PAH formation processes. Different sidechain structures result in different distributions of major products, while different formation pathways and concentrations of precursors lead to different formation tendency of typical PAHs.

The design and development of a TfOH catalysed domino strategy for the double annulation of arenes with propargylic alcohols for the rapid generation of indene based polycyclic systems is reported. The dehydration, intramolecular 6-endo-dig hydroarylation, and cationic cyclization were consecutively promoted by TfOH. The key features of this strategy are the formation of two C–C bonds, unified access to indene polycyclic systems, excellent yields (up to 95%), high atom economy (>90%), an operationally simple procedure, and water being the only byproduct. By extending this strategy, a two-step synthesis of the pentacyclic systems of hypoxylonol A (43% overall yield from α-tetralone), daldinone A (63% overall yield from β-tetralone) and spiro-tetracyclic framework of incarviatone A has also been achieved.

Gas-phase reactions of the o-methylphenyl (o-CH3C6H4) radical with the C3H4 isomers allene (H2C[double bond, length as m-dash]C[double bond, length as m-dash]CH2) and propyne (HC[triple bond, length as m-dash]C-CH3) are studied at 600 K and 4 Torr (533 Pa) using VUV synchrotron photoionisation mass spectrometry, quantum chemical calculations and RRKM modelling. Two major dissociation product ions arise following C3H4 addition: m/z 116 (CH3 loss) and 130 (H loss). These products correspond to small polycyclic aromatic hydrocarbons (PAHs). The m/z 116 signal for both reactions is conclusively assigned to indene (C9H8) and is the dominant product for the propyne reaction. Signal at m/z 130 for the propyne case is attributed to isomers of bicyclic methylindene (C10H10) + H, which contains a newly-formed methylated five-membered ring. The m/z 130 signal for allene, however, is dominated by the 1,2-dihydronaphthalene isomer arising from a newly created six-membered ring. Our results show that new ring formation from C3H4 addition to the methylphenyl radical requires an ortho-CH3 group - similar to o-methylphenyl radical oxidation. These reactions characteristically lead to bicyclic aromatic products, but the structure of the C3H4 co-reactant dictates the structure of the PAH product, with allene preferentially leading to the formation of two six-membered ring bicyclics and propyne resulting in the formation of six and five-membered bicyclic structures.

On one hand, the construction of two fused five-membered carbocyclic rings remains an extremely challenging topic in organic synthesis. On the other hand, transition-metal-catalyzed dienyne cycloaddition reactions have become one of the most powerful methods for the construction of diverse cyclic frameworks. Nevertheless, these methods are limited to noble transition-meal catalysis and non-radical cycloaddition modes. Here, a radical Smiles rearrangement strategy for allowing an unprecedented [3 + 2]/[3 + 2] carboannulation of dienynes with arylsulfonyl chlorides using cheap copper catalysis is described. This cascade method represents a novel cycloaddition mode for dienyne chemistry, which occurs by the sequence of addition of arylsulfonyl radical to a dienyne, a Smiles rearrangement and radical annulation to access cyclopenta[a]indene-fused quinolinones with excellent diastereoselectivity.

Gold-catalyzed reactions of conjugated haloacetylenes are well known and usually result in the formation of addition or dimerization products. Herein, we report a gold-catalyzed reaction of non-conjugated­ haloacetylenes, which leads exclusively to the halogenated cyclization products. Remarkable is the gold-catalyzed reaction of tritylhaloacetylenes to haloindene derivatives, as mechanistic studies reveal that an 1,2-aryl shift occurs in the initially formed gold complex. The potential functionalization at the halogen atom and the wide scope of these cyclization reactions make them an attractive method for the construction of cyclic systems.

The synthesis of polycyclic indene derivatives via silver-catalyzed carbon dioxide fixation on 2-alkynylindene derivatives was achieved by nucleophilic addition of the indenyl anion to carbon dioxide involving carbon-carbon bond formation and subsequent intramolecular cyclization to the alkyne part activated by a silver catalyst. This cascade process could be applied to various substrates to obtain the corresponding products in high yields. The endo/exo selectivity of the cyclization could be controlled by the steric or electronic effect of the substituents on the substrates, and 6-endo-selective cyclization was realized to afford α-pyrone-fused indenes.

A straightforward method for the synthesis of spiro[cyclobuta[a]indene-7,1'-cyclobutane] derivatives from cyclobutanols has been developed via one-pot [3+2] spiroannulation. A series of new spiro[cyclobuta[a]indene-7,1'-cyclobutane] derivatives are facilely synthesized in good yields under mild reaction conditions.

An effective strategy to synthesize spirocyclic compounds, [imidazole-4,1′-indene], has been efficaciously developed relied on Rh(III)-catalyzed [3 + 2] spirocyclization of 2H-imidazoles and 1,3-di...

Benzothiophene, benzofuran, indole, and indene derivatives are privileged heterocyclic motifs. These are present in a wide range of bioactive natural products and pharmaceutical drugs and are the subject of materials science research. However, the construction of benzothiophene, benzofuran, indole, and indene frameworks have been long-standing challenges to organic chemists. In this review, we classify the derivatives of four structures synthesized from 2-benzylidene-1-benzofuran-3-one and their analogues in terms of their ring size (from three- to ten-membered) and type (fused or spiro), as well as summarizing the developments of this field. Finally, we discuss the ring opening and 1,4-addition reactions.

Herein, we report free-radical-initiated polymerization of various cyclic monomers such as 2,3-dihydro furan (DHF), 2,3-dihydro-5-methyl-furan (MDHF), benzo[b]furan (BF), and indene (I) under high ...

A series of hydrogen-bonded complexes between N-heterocyclic analogs of Indene and amino acid side-chain mimics have been analyzed employing second-order Moller-Plesset perturbation (MP2) theory and density functional theory with dispersion function (DFT-D) calculations with the aim of gaining greater insight in to the nature of intermolecular interactions in these systems. In this study, the hydrogen bonding ability of N-heterocyclic analogs of Indene towards amino acid side-chain mimics follows the sequence Azaindazole (AIND) > Indazole (IND) > Azaindole (AIN) > Indole (IN) whereas the hydrogen bonding ability of amino acid side-chain mimics towards N-heterocyclic analogs of Indene follows the sequence AcOH > MeNH2 > MeOH > MeSH. Bader’s theory of atoms in molecules (AIM) and natural bond orbitals (NBO) analyses are employed to elucidate the interaction characteristics in the complexes under study. The purpose of conducting these studies is to measure the relative strength of hydrogen bonding interactions such as N-H···O=C, N-H···O, N-H···S, N-H···N, and O-H···N in these complexes and their role in providing stability to the complexes. The AIM theory shows good correlation of the electron density and its Laplacian at the bond critical points (BCP) with the computed stabilization energy for all the complexes under study.

3-Aryl-1-(trifluoromethyl)prop-2-yn-1-iminium triflate salts represent a novel, highly reactive class of acetylenic iminium salts. Herein we present several reactions which are based on the electron-poor acetylenic bond and on the high electrophilicity of the CF3-substituted iminium group. These salts were found to be highly reactive dienophiles in Diels–Alder reactions with cyclopentadiene, 2,3-dimethylbutadiene and even anthracene. At higher temperature, the cycloadducts undergo an intramolecular SE(Ar) reaction leading to condensed carbocycles incorporating a 1-(trifluoromethyl)-1-(dimethylamine)indene ring system. With styrenes and some substituted styrenes, cascade reactions take place, which likely include cyclobutene and several cationic intermediates and mainly yield 2-(1-phenylvinyl)indenes. In a similar reaction cascade, a fulvene derivative was obtained with 1,4-diphenylbutadiene as the substrate.

Homogeneous liquid-phase oxidation of alkenes (allylbenzene, cis-cyclooctene, 4-chlorostyrene, styrene, 2-norbornene, 1-methyl cyclohexene, indene, lemonine, and 1-hexene) were catalyzed by using vanadium complex [VO(hyap)(acac)2] in existence of H2O2. The complex [VO(hyap)(acac)2] was formed as a crystal by the reaction of [VO(acac)2] and 2-hydroxyacetophenone (hyap) in the presence of methanol by refluxing the reaction mixture. Various analytical and spectroscopic techniques, namely FTIR, ESI–MS, UV–Vis, single-crystal XRD, and EPR, were used to analyze and optimize the structure of the complexes.

Oxidation reactions of highly unsaturated cyclic hydrocarbons are very important in combustion, competing with their participation in PAH and soot growth. One of the key oxidation pathways at combustion conditions is the reaction with hydroxyl radicals. Cyclopentadiene (C5H6) and indene (C9H8) are typical PAH precursors, which have highly unsaturated penta-ring structure. In this study, rate coefficients of the reactions of hydroxyl radical with cyclopentadiene and indene were measured behind reflected shock waves over the temperature range of 828–1390 K and pressure near 1 atm. Hydroxyl radicals were monitored by a narrow line-width laser absorption near 306.7 nm. The measured rate coefficients may be expressed as k C 5 H 6 + OH = 3 . 68 − 0.23 + 0.27 × 10 13 e − ( 1742 . 5 − 77 + 75 ) / T and k C 9 H 8 + OH = 1 . 44 − 0.14 + 0.10 × 10 13 e − ( 1497 . 8 − 72 + 130 ) / T cm3 mol−1 s−1. Our experimental results showed that the reaction of hydroxyl radicals with cyclopentadiene is about two times faster than that of indene, and the indene + OH reaction exhibited a relatively weaker temperature dependence. Chemical kinetic simulations, carried out with a detailed model, showed the sensitivity of model performance to these reactions and the potential of model improvement with our measured rate coefficients.

Commercially available p-aminobenzoic acid was used as a precursor for the synthesis of novel fused, non-fused, and spiro polyheterocyclic derivatives bearing indene, imidazole, pyrazole, and/or triazine nucleus via addition to simple and accessible reagents such as ninhydrin, o-phenylenediamine, and carbon disulfide. The experimental procedures were straightforward and simple, the products were isolated in 15–86% yields, and. their structure was confirmed by spectroscopic data. The synthesized compounds were evaluated for their antibacterial activity against some Gram-positive and Gram-negative bacteria.

Tin-based halide perovskite materials are promising ecofriendly light absorbers with similar optoelectronic properties to lead-based ones. However, their solar cells have suffered from considerably...

A weakly coordinating, carbonyl-assisted C–H activation of aromatic systems with α,β-unsaturated ketone and subsequent aldol condensation has been developed using a Cp*Co(CO)I2 catalyst. The develo...

A simple protocol to synthesize indenes efficiently by PTSA catalyzed tandem Friedel–Crafts alkylation/hydroarylation of tertiary propargylic alcohol with electron-rich arenes is described. The desired indenes were obtained regioselectively in good to very good yields under mild reaction conditions. The allene intermediate was isolated to get an insight into the mechanistic pathway of the indene forming reaction.

An efficient synthetic approach to the tricyclic 1,7a-dihydro-1,3a-ethano-indene and 1,8a-dihydro-1,3a-ethano-azulene skeletons from suitable propargyl vinyl ethers is based on a one-pot, multistep process entailing a gold(I)-catalyzed propargyl Claisen rearrangement/Nazarov cyclization, a [4+2] cycloaddition of the formed six- or seven-membered ring-fused cyclopentadiene system, and a final protection step for the easy isolation and purification of the products by chromatography.

A chiral aluminum complex controlled, enantioselective nickel-catalyzed domino reaction of aryl nitriles and alkynes proceeding by C-CN bond activation was developed. The reaction provides various indenes, bearing chiral all-carbon quaternary centers, under mild reaction conditions in yields of 32 to 91 % and ee values within the 73-98 % range. The reaction mechanism and aspects of stereocontrol were investigated by DFT calculations.

In this paper, we revealed a metal-free and visible light photoinduced method for the rapid construction of spirobi[indene] skeletons, providing a simple and efficient way for easy access to spirobi[indene] scaffolds under mild conditions along with a broad substrate scope and good functional group tolerance.

The thermolysis reactions of benzoazacyclodecatrienes under microwave irradiation conditions in toluene at 150 °C afforded complex azabenzo[a]cyclopropa[cd]azulene and (epiminomethano)cyclopenta[a]indene frameworks. Cyclopropanes were established as intermediates of the ultimate thermolysis products.

JP-10 is a potential endothermic hydrocarbon fuel (EHF) with a high energy density for the regenerative cooling technology of advanced aircrafts. In this work, pyrolysis and coking of JP-10 were experimentally studied using an electrically heated tube as a flowing reactor under supercritical conditions (4.5 MPa, 550–735 °C). For the supercritical pyrolysis, dicyclopentadiene, exo-TCD4e, and indane/indene were observed with relatively higher selectivity at low conversion, and the selectivities of typical products (ethene, propene, CPD, cyclopentene, and benzene) were lower compared with that under atmospheric pressure, possibly because of the enhanced bimolecular reactions. The heat sink of JP-10 was approximately 2.5 MJ/kg ascribed to the severe coke formation during the pyrolysis. Further characterizations on cokes indicated that the coke in the bulk fluid was about 70–170 times higher than that deposited on the wall, attributed to rapid formation of polycyclic aromatic hydrocarbons (PAHs) of pyrolysis products rather than the wall catalysis.

A TBHP mediated carbonylation–peroxidation of styrene, α-peroxidation of α-substituted unsymmetrical internal alkenes and concurrent peroxidation–carbonylation–cycloalkylation/cycloetherifiction of internal cyclic alkene (indene) have been developed.

High performance single-crystalline organic field-effect transistors (OFETs) based on the derivatives of a single dibenzo[a,e]-pentalene (DBP) skeleton have not been reported. Here, we synthesize two novel compounds, 5,10-bis((E)-2-(thiophen-2-yl)vinyl)indeno[2,1-a]indene (TEP) and [4′-(methoxyl)styryl]dibenzopentalene (OSDP), and demonstrate single-crystalline OFET devices. TEP OFETs exhibit a high record of hole mobility up to 1.02 cm2 V−1 s−1 among DBP derivatives, which is an order of magnitude higher than that of OSDP OFETs. The investigation indicates that the different substituent groups and resulting packing arrangements determine their distinct charge transport properties. The comparative results may provide guidance for the rational design and development of high-performance organic semiconducting materials in the future.