- Diels-Alder reactions of masked p-benzoquinones
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Phenylthiomonoketal 3 works effectively as masked p-benzoquinone in Diels-Alder reactions. These cycloadditions may be performed with certain Lewis acid catalysts and give rise exclusively to endo adducts with a good to excellent anti-facial selectivity. 2000 Elsevier Science Ltd.
- De March, Pedro,Figueredo, Marta,Font, Josep,Rodríguez, Sonia
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- A model synthesis of the bicyclic core structure of the furanoheliangolide sesquiterpenes
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A bicyclo[6.2.1]undecane structure, a model for the core structure of several biologically active furanoheliangolide sesquiterpenes, was synthesized through a retro-aldol reaction from a tricyclo-[6.2.1.02,7]undecane. The required tricyclic compound was prepared by a Diels-Alder reaction followed by minor transformations. (C) 2000 Elsevier Science Ltd.
- Constantino,Beatriz,Da Silva
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- Revisiting the stability of endo/exo diels-alder adducts between cyclopentadiene and 1,4-benzoquinone
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In this work it is presented a detailed theoretical analysis of the relative stability of endo/exo Diels-Alder adducts formed by the reaction between cyclopentadiene (1) and 1,4-benzoquinone (2). The intrinsic reaction coordinate (IRC) showed the existence of only one transition state for the reaction studied, for both endo 3 and exo 4 adducts. The energies of both adducts were obtained at high level of theory (CBS-Q) confirming that the endo adduct is more stable than exo, which is in the opposite way to the observed in reactions that usually follow Alder's rule. An electronic structure analysis was performed through NBO methodology, indicating that the attractive delocalization interaction predominates over the steric repulsive interaction in the endo adducts. In summary, for the studied cycloaddition reaction the endo adduct is the thermodynamic and kinetic product, which can be also confirmed by experimental data mentioned in this work.
- Tormena, Claudio F.,Lacerda Jr., Valdemar,De Oliveg, Kleber T.
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- Diels-Alder reactions in confined spaces: The influence of catalyst structure and the nature of active sites for the retro-Diels-Alder reaction
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Diels-Alder cycloaddition between cyclopentadiene and p-benzoquinone has been studied in the confined space of a pure silica zeolite Beta and the impact on reaction rate due to the concentration effect within the pore and diffusion limitations are discussed. Introduction of Lewis or Br?nsted acid sites on the walls of the zeolite strongly increases the reaction rate. However, contrary to what occurs with mesoporous molecular sieves (MCM-41), Beta zeolite does not catalyse the retro-Diels-Alder reaction, resulting in a highly selective catalyst for the cycloaddition reaction.
- Cantín, ángel,Gomez, M. Victoria,De La Hoz, Antonio
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- 1 Hand 13 C NMR spectral data of bioactive cage-like polycyclic compounds
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Bioactive cage-like polycyclic compounds have attracted the attention of several research groups because of their unique appearance and their biological activities. Their structures were established on the basis of 1 HNMR and 13 CNMR
- Lacerda Jr., Valdemar,Salles, Roberta C.,Beatriz, Adilson,Ito, Felicia M.,Dos Santos, Reginaldo B.,Greco, Sandro J.,De Castro, Eustaquio V. R.,De Lima, Denis P.
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- Diels-Alder reactions between cyclopentadiene analogs and benzoquinone in water and their application in the synthesis of polycyclic cage compounds
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Diels-Alder reactions between cyclopentadiene analogs and p-benzoquinone were explored in water and yielded 83-97% product, higher than the results reported in water with a catalyst or cetrimonium bromide (CTAB) micelles. The novel adduct 10 was synthesized and further used to synthesize the bi-cage hydrocarbon 4,4′-spirobi[pentacyclo[5.4.0.02,6.03,10.05,9]undecane], which has a high density (1.2663 g cm-3) and a high volumetric heat of combustion (53.353 MJ L-1). Four novel bi-cage hydrocarbon compounds were synthesized in water using this method starting from 2,2′-bi(p-benzoquinone) and cyclopentadiene analogs.
- Shi, Yijun,Liu, Xuejing,Han, Ying,Yan, Peng,Bie, Fusheng,Cao, Han
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- Open and rearranged norbornane derived polycyclic cage molecules as potential neuroprotective agents through attenuation of MPP+- and calcium overload-induced excitotoxicity in neuroblastoma SH-SY5Y cells
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The neuroprotective effects of closed polycyclic cage molecules such as NGP1-01, memantine and amantadine have been extensively explored. These effects are mostly linked to the antagonism of the N-methyl-D-aspartate (NMDA) receptor- and the blockage of vo
- Egunlusi, Ayodeji O.,Malan, Sarel F.,Omoruyi, Sylvester I.,Ekpo, Okobi E.,Palchykov, Vitalii A.,Joubert, Jacques
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- Synthesis of 4-oxatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione derivatives as lead scaffolds for neuroprotective agents
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Neurodegenerative disorders are characterised by progressive loss of neuronal functions. Of the proposed mechanisms, excitotoxicity, mediated by prolonged glutamate activation and calcium overload, is prominent. NGP1-01, a polycyclic cage amine, and tricyclo[6.2.1.02,7]undec-9-ene-3,6-dione have been shown to display calcium-modulating properties. In this study, we synthesised structurally-related 4-oxatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione as the base scaffold, and incorporated various functional moieties through aminolysis, to afford a series of imide derivatives. All final compounds were obtained in yields between 47-97% and their structures were confirmed by NMR, IR and MS. These structurally-related derivatives could potentially act as neuroprotective agents. Additionally, their synthetic versatilities could make them precursors, as lead compounds, to potential pharmacologically-active agents.
- Egunlusi, Ayodeji O.,Malan, Sarel F.,Joubert, Jacques
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- Pd(II)-Catalyzed Enantioselective Desymmetrization of Polycyclic Cyclohexenediones: Conjugate Addition versus Oxidative Heck
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Pd(II)-catalyzed desymmetrization of polycyclic cyclohexenediones has been achieved with high enantio- and diastereoselectivities. Up to five contiguous stereocenters are desymmetrized, while simultaneously, an additional stereocenter is created by the enantioselective conjugate addition. Surprisingly, the conjugate addition products dominate even under typical oxidative Heck conditions, and these observations may provide some insight into the competition between the two related reactions.
- Lamb, Claire J. C.,Vilela, Filipe,Lee, Ai-Lan
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supporting information
p. 8689 - 8694
(2019/11/03)
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- NORBORNENE-BASED COMPOUND AND METHOD OF PREPARING THE NORBORNENE-BASED COMPOUND
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The present invention relates to norbornene-based compound. The present invention provides the norbornene-based compound capable of imparting improved impact performance, heat resistance, and excellent transparency to a copolymer prepared by incorporating a norbornene-based monomer into a benzene ring.COPYRIGHT KIPO 2018
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Paragraph 0060-0069
(2018/12/12)
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- High Activity and Efficient Turnover by a Simple, Self-Assembled "artificial Diels-Alderase"
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The Diels-Alder (DA) reaction is a cornerstone of synthesis, yet Nature does not use catalysts for intermolecular [4+2] cycloadditions. Attempts to create artificial "Diels-Alderases" have also met with limited success, plagued by product inhibition. Using a simple Pd2L4 capsule we now show DA catalysis that combines efficient turnover alongside enzyme-like hallmarks. This includes excellent activity (kcat/kuncat > 103), selective transition-state stabilization comparable to the most proficient DA catalytic antibodies, and control over regio- and chemoselectivity that would otherwise be difficult to achieve using small-molecule catalysts. Unlike other catalytic approaches that use synthetic capsules, this method is not defined by entropic effects; instead multiple H-bonding interactions modulate reactivity, reminiscent of enzymatic action.
- Martí-Centelles, Vicente,Lawrence, Andrew L.,Lusby, Paul J.
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supporting information
p. 2862 - 2868
(2018/03/08)
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- NORBORNENE-BASED COMPOUND AND METHOD OF PREPARING THE NORBORNENE-BASED COMPOUND
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The present invention relates to a norbornene-based compound. According to the present invention, suggested is a norbornene-based compound which is a monomer of a polycarbonate copolymer in which a benzene ring is included in an embodiment; and which includes norbornene, thereby imparting improved impact performance, heat resistance and excellent transparency to a copolymer produced by using the norbornene-based compound.
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Paragraph 0048-0057
(2019/02/16)
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- Catalytic Enantioselective Desymmetrization of Norbornenoquinones via C(sp2)-H Alkylation
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The enantioselective Diels-Alder (DA) reaction with monosubstituted p-benzoquinones is an unmet challenge. A new approach for the enantioselective synthesis of monosubstituted quinone-DA adducts is presented based on C(sp2)-H alkylative desymmetrization of meso-DA adducts. Catalyzed by a tertiary amino-thiourea derivative, this reaction utilizes nitroalkanes as the alkylating agents and generates densely functionalized products bearing at least four contiguous stereogenic centers remote from the reaction site with excellent enantioselectivities.
- Sarkar, Rahul,Mukherjee, Santanu
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supporting information
p. 6160 - 6163
(2016/12/09)
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- Synthesis and Biological Evaluation of Pentacycloundecylamines and Triquinylamines as Voltage-Gated Calcium Channel Blockers
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Preclinical studies for neurodegenerative diseases have shown a multi-targeted approach to be successful in the treatment of these complex disorders with several pathoetiological pathways. Polycyclic compounds, such as NGP1-01 (7a), have demonstrated the ability to target multiple mechanisms of the complex etiology and are referred to as multifunctional compounds. These compounds have served as scaffolds with the ability to attenuate Ca2+ overload and excitotoxicity through several pathways. In this study, our focus was on mitigating Ca2+ overload through the L-type calcium channels (LTCC). Here, we report the synthesis and biological evaluation of several novel polycyclic compounds. We determined the IC50 values for both the pentacycloundecylamines and the triquinylamines by means of a high-throughput fluorescence calcium flux assay utilizing Fura-2/AM. The potential of these compounds to offer protection against hydrogen peroxide-induced cell death was also evaluated. Overall, 8-benzylamino-8,11-oxapentacyclo[5.4.0.02,6.03,10.05,9]undecane (NGP1-01, 7a) had the most favorable pharmacological profile with an IC50 value of 86 μM for LTCC inhibition and significant reduction of hydrogen peroxide-induced cell death. In general, the triquinylamines were more active as LTCC blockers than the oxa-pentacycloundecylamines. The aza-pentacycloundecylamines were potent LTCC inhibitors, with 8-hydroxy-N-phenylethyl-8,11-azapentacyclo[5.4.0.02,6.03,10.05,9]undecane (8b) also able to offer significant protection in the cell viability assays.
- Young, Lois-May,Geldenhuys, Werner J.,Domingo, Olwen C.,Malan, Sarel F.,Van Der Schyf, Cornelis J.
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p. 252 - 267
(2016/04/26)
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- Palladium(0)-Catalyzed Methylcyclopropanation of Norbornenes with Vinyl Bromides and Mechanism Study
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An unusual methylcyclopropanation from [2 + 1] cycloadditions of vinyl bromides to norbornenes catalyzed by Pd(OAc)2/PPh3 in the presence of CH3ONa and CH3OH has been established. A methylcyclopropane subunit was installed by a 3-fold domino procedure involving a key protonation course. Preliminary deuterium-labeling studies revealed that the proton came from methyl of CH3OH and also exposed an additional hydrogen/deuterium exchange process. These two proton-concerned reactions were fully chemoselective.
- Mao, Jiangang,Xie, Hujun,Bao, Weiliang
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supporting information
p. 3678 - 3681
(2015/08/18)
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- The Diels-Alder reactions of para-benzoquinone nitrogen-derivatives: An experimental and theoretical study
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An experimental and theoretical study of the comparative reactivity and selectivity of the Diels-Alder reactions of para-benzoquinones and three nitrogen derivatives have been performed. The mono-oximes derivatives do not react under the tested reaction conditions, whereas the tosylated mono-oximes react slowly. However, the mono N-tosyl imines show excellent reactivity, and superior to the parent parabenzoquinones. DFT calculations support these experimental results.
- Uliana, Marciana P.,Servilha, Bruno M.,Alexopoulos, Olga,De Oliveira, Kleber T.,Tormena, Cláudio F.,Ferreira, Marco A.B.,Brocksom, Timothy J.
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p. 6963 - 6973
(2015/11/09)
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- Use of flash vacuum thermolysis in a stereocontrolled synthesis of optically active alkyl-substituted cyclopentenones with fragrant properties
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The synthesis of four pairs of enantiopure antipodal substituted cyclopentenones is described. The synthetic sequences first comprise the preparation of a tricyclo[5.2.1.02,6]deca-4,8-dienone system, a subsequent kinetic enzymatic resolution of the appropriately functionalized tricyclic system, followed by a series of chemical transformations to install the desired substituents, and finally a retro Diels-Alder reaction using flash vacuum thermolysis to give the target products in high chemical and optical yields. The strategy makes effective use of the concept of transient chirality involving complete stereochemical control over reactions with the chiral tricyclic systems before thermal removal of the cyclopentadiene.
- Zwanenburg, Binne,Volkers, Andries A.,Klunder, Antonius J. H.
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p. 1234 - 1242
(2014/10/16)
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- The first cns-active carborane: A novel p2x7 receptor antagonist with antidepressant activity
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Relative to other polycyclic frameworks (1-3), a carborane cage (4 and Cs·5) exerts a significant biological effect as an inhibitor of the purinergic P2X7 receptor (P2X7R) which allows one to target depression in vivo and thus demonstrate, for the first time, that a carborane has the capacity to modify CNS activity.
- Wilkinson, Shane M.,Gunosewoyo, Hendra,Barron, Melissa L.,Boucher, Aurelie,McDonnell, Michelle,Turner, Peter,Morrison, Daniel E.,Bennett, Maxwell R.,McGregor, Iain S.,Rendina, Louis M.,Kassiou, Michael
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p. 335 - 339
(2014/06/09)
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- Solar driven uphill conversion of dicyclopentadiene to cyclopentadiene: An important synthon for energy systems and fine chemicals
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The retro Diels-Alder conversion of endo-dicyclopentadiene to cyclopentadiene (Cp)-which is thermodynamically uphill under ambient conditions (ΔG = +9.7 kcal mol-1; values based on computation at 273 K following CBS-QB3 methodology)-was carried out at 175-190 °C in neat state using solar energy. The reaction is thermodynamically favorable at elevated temperature. Considering heat release from the reverse reaction (ΔH = -23.4 kcal mol-1), the energy storage efficiency was computed to be ca. 5.5% with respect to the IR component in concentrated solar radiation. Solar energy was further utilized for preparation of a model 2,5-norbornadiene derivative (75% isolated yield) through the cycloaddition reaction of Cp with 4-phenylbut-3-yn-2-one at 150-185 °C. The norbornadiene-quadricyclane system has been proposed for solar energy storage, and its solar assisted synthesis would help reduce its carbon footprint over its life cycle. Norbornadiene synthesis using solar energy may also be of interest for greener processing of fuels derived from this compound. Cookson's cage ketone, which too has been proposed as an energy storage medium, was additionally synthesized from the Diels-Alder adduct of Cp and p-benzoquinone employing concentrated solar photo-thermochemical conditions. The reaction proceeded rapidly (15 min) and gave the desired product in 96% isolated yield. Besides the above applications, Cp is an important synthon in the preparation of fine chemicals.
- Dinda, Milan,Chakraborty, Supratim,Kanti Si, Mrinal,Samanta, Supravat,Ganguly, Bishwajit,Maiti, Subarna,Ghosh, Pushpito K.
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p. 54558 - 54564
(2015/02/05)
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- N-substituted 8-aminopentacyclo[5.4.0.02,6.03,10. 05,9]undecanes as σ receptor ligands with potential neuroprotective effects
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Several libraries of similarly N-substituted 8-aminopentacyclo[5.4.0.0 2,6.03,10.05,9]undecanes (9), N-methyl-8-aminopentacyclo[5.4.0.02,6.03,10.0 5,9]undecanes (14), and N-methyl-11-aminop
- Banister, Samuel D.,Manoli, Miral,Barron, Melissa L.,Werry, Eryn L.,Kassiou, Michael
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p. 6038 - 6052
(2013/09/23)
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- D3-trishomocubane-4-carboxylic acid as a new chiral building block: Synthesis and absolute configuration
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The preparation of (±)-D3-trishomocubanone on a multigram scale from 1,4-benzoquinone and cyclopentadiene was optimized to give the target product in 39% overall yield, that was transformed to (±)-D 3-trishomocubane-4-carboxylic acid via a three-step procedure involving the Corey-Chaykovsky reaction followed by boron trifluoride-diethyl ether catalyzed epoxide ring opening and further oxidation. Optically active (+)-D3-trishomocubane-4-carboxylic acid was prepared through the resolution of the racemate by crystallization of its salt with (R)-phenylethylamine; the absolute configuration was assigned by X-ray crystal structure analysis. Georg Thieme Verlag Stuttgart · New York.
- Gaidai, Alexandr V.,Volochnyuk, Dmitriy M.,Shishkin, Oleg V.,Fokin, Andrey A.,Levandovskiy, Igor A.,Shubina, Tatyana E.
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experimental part
p. 810 - 816
(2012/05/07)
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- A σ1 receptor pharmacophore derived from a series of N-substituted 4-azahexacyclo[5.4.1.02,6.03,10.0 5,9.08,11]dodecan-3-ols (AHDs)
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A library of N-substituted 4-azahexacyclo[5.4.1.02,6.0 3,10.05,9.08,11]dodecan-3-ols (AHDs) was synthesized and subjected to competition binding assays at σ1 and σ2 receptors, as well as off-target screening of representative members at 44 other common central nervous system (CNS) receptors, transporters, and ion channels. Excluding 3 low affinity analogs, 31 ligands demonstrated nanomolar Ki values for either σ receptor subtype. Several selective σ1 and σ2 ligands were discovered, with selectivities of up to 29.6 times for σ1 and 52.4 times for σ2, as well as several high affinity, subtype non-selective ligands. The diversity of structures and σ1 affinities of the ligands allowed the generation of a σ1 receptor pharmacophore that will enable the rational design of increasingly selective and potent σ1 ligands for probing σ1 receptor function.
- Banister, Samuel D.,Manoli, Miral,Doddareddy, Munikumar Reddy,Hibbs, David E.,Kassiou, Michael
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supporting information
p. 6053 - 6058
(2012/10/30)
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- Preparation and complete 1 H and 13C assignment of some pentacyclo[5.4.0.02,6.03,10.05,9]undecane- 8,11-dione (PCUD) derivatives
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The preparation of a number of alkyl and alkoxy derivatives of pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11- dione derivatives utilising a cheap, practical, low energy, 'green', single-pass continuous flow photochemical reactor is reported. Their 1 H and 13C NMR spectra are fully assigned, revealing some general characteristics not previously reported for this class of compound, which should aid the assignment and prediction of the NMR spectra of PCUD derivatives. Copyright
- Kenwright, Alan M.,Sellars, Jonathan D.
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p. 803 - 808
(2013/01/15)
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- Chemoselective epoxidation of electron rich and electron deficient olefins catalyzed by meso-tetraarylporphyrin iron(iii) chlorides in imidazolium ionic liquids
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The oxygenation of substrates containing both electron rich and electron deficient olefins (1a-b) catalyzed by 5,10,15,20-tetraarylporphyrinatoiron(iii) chlorides [TAPFe(iii)Cl] with H2O2 gave epoxides at both electron rich and deficient olefin (2a-b, 3a-b), while with iodosyl benzene (PhIO) gave the epoxides only at electron rich olefin (3a-b) in imidazolium ionic liquids (ILs). Further reaction of 2a-b with sodium hydroxide in methanol gave 4a-b by base catalysed rearrangement of enedione epoxides. Similar reaction of 4a-b with H2O2 or PhIO gave the major epoxides of electron deficient olefins and electron rich olefins. The ferric peroxy anions (TAP-FeIII-OO-) are effective intermediates in the epoxidation of electron deficient olefins, whereas the high valent oxoferrylporphyrin π-cation radicals (TAP-FeIVO+) are involved in the epoxidation of electron rich olefins. The ILs provide the special microenvironments by the interactions of cations and anions, in which the generation of the active intermediates from TAPFe(iii)Cl/[Bmim][PF 6] and monooxygen donors could be accelerated significantly. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012.
- Singh, Pradeep Pratap,Ambika,Chauhan
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experimental part
p. 650 - 655
(2012/05/04)
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- The importance of hydrogen bonding to stereoselectivity and catalyst turnover in gold-catalyzed cyclization of monoallylic diols
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Density functional calculations and experiment were used to examine the mechanism, reactivity, and origin of chirality transfer in monophosphine Au-catalyzed monoallylic diol cyclization reactions. The lowest energy pathway for cyclization involves a two-
- Ghebreghiorgis, Thomas,Biannic, Berenger,Aponick, Aaron,Kirk, Brian H.,Ess, Daniel H.
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supporting information
p. 16307 - 16318,12
(2020/09/09)
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- Anomalies in the asymmetric transfer hydrogenation of several polycyclic meso compounds
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Over the course of developing a multigram scale preparation of epoxy quinol 1 via asymmetric transfer hydrogenation (ATH) using the Noyori Ru(arene)(S,S-TsDPEN) catalysts, we observed several unexpected phenomena, including (i) chemoselective alkene versus ketone reduction of an enedione, (ii) a significant arene ligand effect (p-cymene vs mesitylene) on the reaction pathway, and (iii) solvent-based reversal of the sense of enantioinduction.
- Clay, David R.,McIntosh, Matthias C.
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experimental part
p. 1691 - 1694
(2012/05/05)
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- A convenient road to 1-chloropentacycloundecanes - A joint experimental and computational investigation
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An efficient synthetic strategy to obtain 1-chloro-Cs- trishomocubane and 1-chloro-D3-trishomocubane is described. 1-Chloro-Cs-trishomocubane is synthesized by a regioselective Diels-Alder reaction, and B3PW91/6-31G(d,p) calculations offer a plausible explanation of the reaction mechanism. Surprisingly, 1-chloro-C s-trishomocubane does not undergo an acid-catalyzed rearrangement to form 1-chloro-D3-trishomocubane and was obtained by chlorosulfation of Cookson's diketone. A possible mechanism of the reaction involving the formation of Cs- and D3-trishomocubane nonclassical cations was proposed on the basis of a mechanistic [B3PW91/6-31G(d,p) and MP2/cc-pVDZ] study. An efficient method to prepare 1-substituted pentacycloundecanes is described. Simple modification of the starting material for the Diels-Alder reaction gives 1-Cs-trishomocubane derivatives readily. Chlorosulfation of Cookson's diketone in four steps gives 1-chloro-D3-trishomocubane in good yields. The proposed mechanism of the reactions is explained by DFT and MP2 calculations. Copyright
- Sharapa, Dmitry I.,Gayday, Alexander V.,Mitlenko, Alena G.,Levandovskiy, Igor A.,Shubina, Tatyana E.
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experimental part
p. 2554 - 2561
(2011/06/10)
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- Synthetic access to the chlorocyclopentane cores of the proposed original and revised structures of palau'amine
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(Chemical Equation Presented) Core knowledge: The synthesis of the functionalized cores of both the originally proposed and revised structures of palau'amine have been achieved (see structures). A Diels-Alder/[3,3]-sigmatropic rearrangement sequence and a Beckmann rearrangement enable the stereo-controlled formation of the highly congested cores.
- Bultman, Michael S.,Ma, Jun,Gin, David Y.
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body text
p. 6821 - 6824
(2009/04/07)
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- Promotion of organic reactions by interfacial hydrogen bonds on hydroxyl group rich nano-solids
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Surface hydroxyl group rich nano-structured solids dramatically increase the rate of several organic reactions; such effect is attributed to the formation of interfacial hydrogen bonds between the surface hydroxyl groups and the reactants; this catalytic
- Niu, Fang,Liu, Chang-Chang,Cui, Zhi-Min,Zhai, Jin,Jiang, Lei,Song, Wei-Guo
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supporting information; body text
p. 2803 - 2805
(2009/02/05)
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- Catalyst-free one-pot synthesis of 2,4,6-triaryl-1,4-dihydropyridines in ionic liquid and their catalyzed activity on two simple Diels-Alder reactions
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A series of 2,4,6-triaryl-1,4-dihydropyridines bearing a hydroxyl group was synthesized greenly by the cascade aldol/Michael/addition reaction of aromatic aldehyde, acetophenone, and NH4OAc (1:2:excessive) in ionic liquid [BmIm][BF4] without any catalyst. The results of their catalyzed activity on two simple Diels-Alder reactions indicated that this kind of compound containing a poly aryl ring can be used as an effective catalyst on the Diels-Alder reaction. This method, because of its environmental friendliness, simplicity, mild conditions, effectiveness, and lower costs, is suitable for the synthesis of arrays of compounds. Copyright Taylor & Francis Group, LLC.
- Wu, Hui,Wan, Yu,Lu,Shen, Yang,Ye,Zhang
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p. 666 - 673
(2008/09/16)
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- Synthesis and biological evaluation of rigid polycyclic derivatives of the Diels-Alder adduct tricyclo[6.2.1.02,7]undeca-4,9-dien-3,6-dione
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Part of our research program concentrates on the discovery of new bioactive compounds prepared either by total synthesis or molecular transformation of compounds with bioactivity profiles. In this work we have focused our interest on chemical transformati
- Ito, Felicia Megumi,Petroni, Jacqueline Marques,De Lima, Denis Pires,Beatriz, Adilson,Marques, Maria Rita,De Moraes, Manoel Odorico,Costa-Lotufo, Leticia Veras,Montenegro, Raquel Carvalho,Magalhaes, Hemerson Iury Ferreira,Do O Pessoa, Claudia
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p. 271 - 282
(2007/10/03)
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- Enhanced Diels-Alder reactions: on the role of mineral catalysts and microwave irradiation in ionic liquids as recyclable media
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This manuscript explores in detail the combined effect of solid supports or microwave irradiation in ionic liquids on a series of Diels-Alder reactions involving 1,3-cyclopentadiene and numerous dienophiles.
- López, Ignacio,Silvero, Guadalupe,Arévalo, María José,Babiano, Reyes,Palacios, Juan?Carlos,Bravo, José Luis
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p. 2901 - 2906
(2007/10/03)
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- Recyclable organotungsten Lewis acid and microwave assisted Diels-Alder reactions in water and in ionic liquids
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The water-soluble, organotungsten Lewis acid, [OP(2-py)3W(CO) (NO)2](BF4)2 (1), was synthesized and characterized. A series of 1-catalyzed Diels-Alder reactions were investigated under conventional heating or microwave heating conditions. The cycloaddition reactions were efficiently conducted in either water or in an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate. The ionic liquid acts as a powerful medium not only for rate- and selectivity enhancements but also for facilitating catalyst recycling. Dramatic rate acceleration via microwave flash heating as compared to thermal heating was observed. Graphical Abstract
- Chen, I-Hon,Young, Jun-Nan,Yu, Shuchun Joyce
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p. 11903 - 11909
(2007/10/03)
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- Efficient preparation of a 1,3-diazidocyclitol as a versatile 2-deoxystreptamine precursor
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A synthesis route toward 2-deoxystreptamine, a common structure in many of the clinically important aminoglycosides, is presented. Starting from p-benzoquinone and cyclopentadiene, 2-deoxystreptamine is synthesized with key steps involving Pd(0)-catalyzed
- Busscher, Guuske F.,Groothuys, Stan,De Gelder, Rene,Rutjes, Floris P. J. T.,Van Delft, Floris L.
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p. 4477 - 4481
(2007/10/03)
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- Polymeric Phosphine Ligand from Ring-Opening Metathesis Polymerization of a Norbornene Derivative. Applications in the Heck, Sonogashira, and Negishi Reactions
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The phosphine-containing polymer 1 is obtained by ruthenium-catalyzed ring-opening metathesis polymerization of the norbornene derivative 2. Polymer 1 is employed as the polymer support in the palladium-catalyzed Heck, Sonogashira, and Negishi reactions,
- Yang, Yun-Chin,Luh, Tien-Yau
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p. 9870 - 9873
(2007/10/03)
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- Cycloadditions of isobenzofuran to a constrained template bearing neighboring dienophiles
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A high yielding synthesis of the pentacyclic diene-dione 1 has enabled investigation of its reactivity as a double dienophile in Diels- Alder [4+2] cycloadditions with isobenzofuran, leading to novel and highly symmetrical three-sided cavitands 3 and 4.
- Stoermer, Martin J.,Butler, Douglas N.,Warrener, Ronald N.,Weerasuria,Fairlie, David P.
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p. 2068 - 2071
(2007/10/03)
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- The synthesis of epi-epoxydon utilising the Baylis-Hillman reaction
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(±)-epi-Epoxydon was synthesised by means of a triethylaluminium/tri-n-butylphosphine-catalysed Baylis-Hillman reaction between an O-protected epoxidised hydroxyquinol core and paraformaldehyde, constituting the first application of the Baylis-Hillman reaction to a highly functionalised β-substituted enone.
- Genski, Thorsten,Taylor, Richard J.K.
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p. 3573 - 3576
(2007/10/03)
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- Improved synthesis of racemic and optically active 4-hydroxycyclohex-2-en-1-one
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A simple and inexpensive synthetic route which affords S-(-)-4-hydroxycyclohex-2-en-1-one (1a) with high stereoselectivity and moderate enantioselectivity is reported. A key step in this procedure involves baker's yeast promoted reduction of 1α,4α,4aα,6,7,8aα-hexahydro-1,4-methanonaphthalene-5,8-dione (3), which affords optically active 8-hydroxy-1α,4α,4aα,8β,8aα-tetrahydro-1,4-methanonaphthalen-5(1H) -one (4a, 80% de, 67% ee) in 32% yield. The absolute configuration of the 3,5-dinitrobenzoate ester of 4a (i.e., 5a) was established unequivocally via single crystal X-ray structural analysis.
- Marchand,Xing,Wang,Bott
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p. 2709 - 2714
(2007/10/03)
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- Eine yttriumhaltige starke Lewis-Saeure zur heterogenen Katalyse der Diels-Alder-Reaktion
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Keywords: Diels-Alder-Reaktionen; Heterogene Katalyse; Lewis-Saeuren; Yttriumverbindungen
- Keshavaraja, Alive,Hegde, Vishnumurthy R.,Pandey, Bipin,Ramaswamy, Arumugamangalam V.,Kumar, Pradeep,Ravindranathan, T.
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p. 2333 - 2336
(2007/10/03)
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- Enantiocontrolled Synthesis of Optically Pure 5-Trimethylsilyl- and 5-Tributylstannyl-cyclohex-2-enones
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Optically pure 5-trimethylsilyl- and 5-tributylstannyl-cyclohex-2-enones have been prepared efficiently in an enantiocontrolled manner starting from the common chiral precursor by employing a novel palladium-mediated elimination reaction as the key step.
- Takano, Seiichi,Higashi, Yasuhiro,Kamikubo, Takashi,Moriya, Minoru,Ogasawara, Kunio
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p. 788 - 789
(2007/10/02)
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- The 1:1 and 2:1 adducts of cyclopentadiene with p-benzoquinone
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The exo-cis isomer (8) of the well-known endo-cis 1:1 adduct (4) of cyclopentadiene and p-benzoquinone has been obtained by heating the endo-cis-anti-cis-endo 2:1 adduct (13) with p-benzoquinone and also by haeting 4 alone.The exo-cis isomer of the 1:1 adduct (11) of cyclopentadiene and p-toluquinone has also been obtained for the first time.Heating of the 2:1 adduct 13 gives a mixture containing the endo-anti-exo isomer 15, the exo-anti-exo isomer 16, and 13.The structures of these two new isomers are assigned on the basis of (i) spectroscopic comparison with 13 and the known endo-syn-endo and endo-syn-exo isomers, 12 and 14; (ii) spectroscopic comparison of the corresponding tetrahydro compounds; and (iii) the conversion of tetrahydro 15 by oxidation and acetylation to the syn-hydroquinone diacetate 28, which is stereoisomeric with the anti-hydroquinone diacetate 25, prepared by similar treatment of tetrahydro 13,14, and 16.It is proposed that interconversion of the 1:1 adducts occurs via dissociation-recombination, interconversion of the tetrahydro 2:1 adducts occurs via enolization, while interconversion of the 2:1 adducts themselves can occur by both routes.
- Yates, Peter,Switlak, Krzysztof
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p. 1894 - 1900
(2007/10/02)
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- Stereochemical Studies by PMR Spektroscopy: Methoxybromination of the Olefinic Bond in Bicylic Systems
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Methoxybromination of the olefinic bond in some typical Diels-Alder adducts with bromine in methanol in the presence of yellow lead oxide or silver nitrate has been effected.The assignment of stereochemistry of the methoxybromo products has been made with the help of PMR spectroscopy.Cyclopentadiene-p-benzoquinone, 6,6-diphenylfulvene-p-benzoquinone and cyclopentadiene-1,4-naphthoquinone Diels-Alder adducts (I-III) undergo exo-cis-addition while anthracene-p-benzoquinone adduct (IV) leads to the formation of trans-product.The bromine atom and the methoxy group of the methoxybromo adduct of IV are present in trans-1,2-diaxial positions in the cyclohexadione ring having chair type conformation.
- Singh, Ashok K.,Verma, Shiva Mohan
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p. 329 - 331
(2007/10/02)
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- A NOVEL, VERSATILE SYNTHETIC APPROACH TO LINEARLY FUSED TRICYCLOPENTANOIDS via PHOTO-THERMAL OLEFIN METATHESIS
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Fifteen examples of a new, speedy and general approach to linearly fused tricyclopentanoids bearing the tricyclo2,6>undecane (triquinane) frame of high contemporary interest is delineated.The key concept in our synthetic sequence to tri
- Mehta, Goverdhan,Srikrishna, A.,Reddy, A. Veera,Nair, Mangalam S.
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p. 4543 - 4559
(2007/10/02)
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- A novel, versatile synthetic approach to linearly fused tricyclopentanoids via photo-thermal olefin metathesis
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Fifteen examples of a new, speedy and general approach to linearly fused tricyclopentanoids bearing the tricyclo[6.3.0.02.6]undecane (triquinane) frame of high contemporary interest is delineated. The key concept in our synthetic sequence to triquinanes is the novel photo-thermal olefin metathesis of cheap, abundantly available Diels-Alder adducts of 1,3-cyclopentadienes and p-benzoquinones. Thus, photolysis of endo-tricyclo[6.2.1.02,7]undeca-4,9-dien-3,6-diones (9a-j, 13a,b)furnished pentacyclo[5.4.0.02,6.03,10.05,9]undecan-8,11-diones (10a-j 14a, b), which on thermal fragmentation of the cyclobutane ring gave cis, syn, cis-tricyclo [6.3.0.02,6]undeca-4,9-dien-3,11-diones (11a-j, 15a,b) in just three steps and in exceptionally good yields. A few interesting transformations of the readily available parent bis-enone 11a which indicates its wider uses in syntheses, are described. Finally, a smooth thermal isomerisation of cis, syn, cis-bis-enones to cis, anti, cis-bis-enones is reported, which further enhances the scope and versatility of our synthetic theme.
- Mehta, Goverdhan,Srikrishna,Veera Reddy,Nair, Mangalam S.
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p. 4543 - 4559
(2014/12/10)
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