- Cucurbiturils Monofunctionalized on the Methylene Bridge and Their Host-Guest Properties
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Monofunctionalization of cucurbiturils is essential for transferring these potent supramolecular macrocyclic hosts into real-world application. Here, we present the synthesis of cucurbit[6]urils 1 and 2 in which one methylene bridge is modified by a single substituent containing a nitro or an ammonium group. We investigated host–guest properties in water and 0.2 M NaCl using 1H?NMR and isothermal titration calorimetry, particularly for 2. The macrocycle 2 self-associated into dimeric aggregates in pure water, but readily disassembled in the presence of NaCl or organic cations. Cucurbit[7]uril was able to encapsulate the ammonium substituent of 2 inside its cavity resulting in a complex of 1 : 1 stoichiometry with an association constant of 3.1×105 M?1. The presented host–guest properties together with further possible derivatization showcase the potential of cucurbiturils modified in the methylene position such as 1 and 2 for the development of advanced supramolecular systems.
- Kandrnálová, Markéta,?indelá?, Vladimír
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supporting information
p. 4733 - 4736
(2021/09/10)
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- Complex Polyheterocycles and the Stereochemical Reassignment of Pileamartine A via Aza-Heck Triggered Aryl C-H Functionalization Cascades
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Structurally complex benzo- and spiro-fused N-polyheterocycles can be accessed via intramolecular Pd(0)-catalyzed alkene 1,2-aminoarylation reactions. The method uses N-(pentafluorobenzoyloxy)carbamates as the initiating motif, and this allows aza-Heck-type alkene amino-palladation in advance of C-H palladation of the aromatic component. The chemistry is showcased in the first total synthesis of the complex alkaloid (+)-pileamartine A, which has resulted in the reassignment of its absolute stereochemistry.
- Bower, John F.,Caiger, Lewis,García-Cárceles, Javier,Hazelden, Ian R.,Jones, Benjamin T.,Langer, Thomas,Lewis, Richard J.
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p. 15593 - 15598
(2021/10/12)
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- Transfer hydrogenations catalyzed by streptavidin-hosted secondary amine organocatalysts
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Here, the streptavidin-biotin technology was applied to enable organocatalytic transfer hydrogenation. By introducing a biotin-tethered pyrrolidine (1) to the tetrameric streptavidin (T-Sav), the resulting hybrid catalyst was able to mediate hydride transfer from dihydro-benzylnicotinamide (BNAH) to α,β-unsaturated aldehydes. Hydrogenation of cinnamaldehyde and some of its aryl-substituted analogues was found to be nearly quantitative. Kinetic measurements revealed that the T-Sav:1 assembly possesses enzyme-like behavior, whereas isotope effect analysis, performed by QM/MM simulations, illustrated that the step of hydride transfer is at least partially rate-limiting. These results have proven the concept thatT-Savcan be used to host secondary amine-catalyzed transfer hydrogenations.
- Santi, Nicolò,Morrill, Louis C.,?widerek, Katarzyna,Moliner, Vicent,Luk, Louis Y. P.
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supporting information
p. 1919 - 1922
(2021/03/02)
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- Synthesis of rac-ɑ-aryl propionaldehydes via branched-selective hydroformylation of terminal arylalkenes using water-soluble Rh-PNP catalyst
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This work detailed the preparation of a class of water-soluble PNP ligands that differed by the nature of the substitute on phenyl ring of ligands. These ligands were incorporated into water-soluble rhodium-PNP complex catalysts that were used to regioselective hydroformylation of a series of terminal arylalkenes, providing efficient access to rac-α-aryl propionaldehydes in good to excellent yield (up to 97%) and branched-regioselectivity (up to 40:1 b/l ratio). Furthermore, gram-scale and diverse synthetic transformation demonstrated synthetic application of this methodology for non-steroidal antiinflammatory drugs.
- Chen, Fen-Er,Gao, Peng,Ke, Miaolin,Liang, Guanfeng,Ru, Tong
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- Heck arylation of allyl alcohol catalyzed by Pd(0) nanoparticles
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Pd(0) nanoparticles ca. 2 nm in diameter were obtained by the reduction of PdCl2 and Pd(OAc)2 in water at 80 °C in the presence of a PVP-stabilizing polymer. Pd(0) NPs were successfully used in the Heck coupling of allyl alcohol with iodo- and bromobenzenes. Iodobenzenes reacted under solventless conditions or in DMF solution producing 3-arylpropanals and 2-arylpropanals as the main products. The same products were obtained in the reaction of bromobenzene in TBAB as the reaction medium. The stability of Pd(0) NPs was evidenced in recycling experiments. Similar Heck coupling results were also obtained with the palladium compounds PdCl2(cod) and Pd(OAc)2 under the same conditions.
- Tarnowicz, Stanis?awa,Alsalahi, Waleed,Mieczyńska, Ewa,Trzeciak, Anna M.
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p. 5605 - 5612
(2017/08/26)
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- Surface bonded Rh-bis(diarylphosphine) on magnetic nanoparticles as a recyclable catalyst for hydroformylation of olefins
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A functionalized nanomaterial having an average particles size of less than 10 nm comprising an iron oxide nanoparticle core and a bis(diarylphosphinomethyl) dopamine based ligand layer anchored to the iron oxide nanoparticle core is disclosed. In addition, a catalyst composition for use in a variety of chemical transformations wherein the bisphosphine groups of the functionalized nanomaterial chelate a catalytic metal is disclosed. In addition, a method for producing the functionalized nanomaterial and a method for the hydroformylation of olefins to aldehydes employing the functionalized nanomaterial with high conversion percentage and high selectivity are disclosed.
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Page/Page column 23-24
(2016/11/21)
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- Scope and mechanism in palladium-catalyzed isomerizations of highly substituted allylic, homoallylic, and alkenyl alcohols
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Herein we report the palladium-catalyzed isomerization of highly substituted allylic alcohols and alkenyl alcohols by means of a single catalytic system. The operationally simple reaction protocol is applicable to a broad range of substrates and displays a wide functional group tolerance, and the products are usually isolated in high chemical yield. Experimental and computational mechanistic investigations provide complementary and converging evidence for a chain-walking process consisting of repeated migratory insertion/β-H elimination sequences. Interestingly, the catalyst does not dissociate from the substrate in the isomerization of allylic alcohols, whereas it disengages during the isomerization of alkenyl alcohols when additional substituents are present on the alkyl chain.
- Larionov, Evgeny,Lin, Luqing,Gune, Laure,Mazet, Clment
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supporting information
p. 16882 - 16894
(2015/01/09)
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- How phenyl makes a difference: Mechanistic insights into the ruthenium(ii)-catalysed isomerisation of allylic alcohols
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[RuCl(η5-3-phenylindenyl)(PPh3)2] (1) has been shown to be a highly active catalyst for the isomerisation of allylic alcohols to the corresponding ketones. A variety of substrates undergo the transformation, typically with 0.25-0.5 mol% of catalyst at room temperature, outperforming commonly-used complexes such as [RuCl(Cp)(PPh3) 2] and [RuCl(η5-indenyl)(PPh3) 2]. Mechanistic experiments and density functional theory have been employed to investigate the mechanism and understand the effect of catalyst structure on reactivity. These investigations suggest a oxo-π-allyl mechanism is in operation, avoiding intermediate ruthenium hydride complexes and leading to a characteristic 1,3-deuterium shift. Important mechanistic insights from DFT and experiments also allowed for the design of a protocol that expands the scope of the transformation to include primary allylic alcohols.
- Manzini, Simone,Poater, Albert,Nelson, David J.,Cavallo, Luigi,Nolan, Steven P.
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p. 180 - 188
(2014/01/06)
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- 3,5-Disubstituted-thiazolidine-2,4-dione analogs as anticancer agents: Design, synthesis and biological characterization
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A series of 2,5-disubstituted-thiazolidine-2,4-dione analogs based on the newly identified lead 1, a potential anticancer agent via the inhibition of the Raf/MEK/extracellular signal regulated kinase (ERK) and phosphatidylinositol 3-kinase (PI3K)/Akt signaling cascades, were synthesized and biologically characterized. A new lead structure, 15, was identified to have improved anti-proliferative activities in U937 cells, to induce apoptosis in U937, M12 and DU145 cancer cells, and to arrest U937 cells at the S-phase. Furthermore, Western blot analysis demonstrated a correlation of the anti-proliferative activity and blockade of the Raf/MEK/ERK and PI3K/Akt signaling pathways. Collectively, these results strongly encourage further optimization of 15 as a new lead with multi-target properties to develop more potent compounds as anticancer agents.
- Liu, Kai,Rao, Wei,Parikh, Hardik,Li, Qianbin,Guo, Tai L.,Grant, Steven,Kellogg, Glen E.,Zhang, Shijun
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p. 125 - 137
(2012/03/08)
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- Pd-catalyzed cascade Heck-Saegusa: Direct synthesis of enals from aryl iodides and allyl alcohol
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A new efficient Pd-catalyzed cascade Heck-Saegusa protocol for the synthesis of synthetically useful α,β-unsaturated aldehydes in high yields from readily available aryl iodides and allyl alcohol has been developed.
- Liu, Jie,Zhu, Jin,Jiang, Hualiang,Wang, Wei,Li, Jian
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supporting information; experimental part
p. 415 - 417
(2010/04/04)
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- Lewis base-promoted hydrosilylation of cyclic malonates: Synthesis of β-substituted aldehydes and γ-substituted amines
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The Lewis base-promoted hydrosilylation of cyclic malonates provides a convenient synthesis of β-substituted aldehydes. No over-reduction to the primary alcohol is observed as the aldehyde functionality is protected until a subsequent hydrolysis step. The
- Frost, Christopher G.,Hartley, Benjamin C.
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scheme or table
p. 3599 - 3602
(2009/09/05)
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- Polymer-supported hantzsch 1,4-dihydropyridine ester: An efficient biomimetic hydrogen source
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An efficient synthesis of a polymer-supported Hantzsch 1,4-dihydropyridine ester has been developed and its use in a variety of reduction reactions was studied using α,β-unsaturated aldehydes, imines and an activated benzoquinone as substrates. Reductive amination using the polymer-supported Hantzsch 1,4-dihydropyridine ester and a catalytic amount of 1.5 M HCl was found to proceed rapidly and with good yields.
- He, Rongjun,Toy, Patrick H.,Lam, Yulin
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experimental part
p. 54 - 60
(2009/04/07)
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- Tandem molybdenum catalyzed hydrosilylations: An expedient synthesis of β-aryl aldehydes
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The synthesis of β-aryl aldehydes utilizing a tandem molybdenum catalyzed hydrosilylation is described. This new functional group interconversion provides an efficient method for the two-carbon homologation of aryl aldehydes.
- Frost, Christopher G.,Hartley, Benjamin C.
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p. 4259 - 4261
(2008/02/12)
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- Nornicotine-organocatalyzed aqueous reduction of α,β-unsaturated aldehydes
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Nornicotine, a native component of tobacco and minor nicotine metabolite, was found to catalyze the chemoselective reduction of α,β-unsaturated aldehydes under homogeneous aqueous conditions. The Royal Society of Chemistry.
- Brogan, Andrew P.,Dickerson, Tobin J.,Janda, Kim D.
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p. 4952 - 4954
(2008/09/17)
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- Conjugate reduction of α,β-unsaturated aldehydes with rhodium(bis-oxazolinylphenyl) catalysts
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α,β-Unsaturated aldehydes were selectively reduced using rhodium(bisoxazolinylphenyl) complexes to give exclusive 1,4-selectivity in the combination of alkoxyhydrosilanes. Georg Thieme Verlag Stuttgart.
- Kanazawa, Yoshinori,Nishiyama, Hisao
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p. 3343 - 3345
(2008/09/18)
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- METHOD FOR HYDROGENATION OF α,β-UNSATURATED CARBONYL COMPOUNDS
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A method for the chemoselective hydrogenation of a,? unsaturated carbonyl compounds is disclosed, in which compounds of general formula (I), where R1 = H, branched, unbranched, saturated or unsaturated 1-30C hydrocarbon group which may have suitable substituents and the hydrocarbon group may have one or more heteroatoms in the chain, aryl or heteroaryl group which can have suitable substituents, R2, R3 and R4 independently = H, F, Cl, Br, I, OH, CN, NO2, NO, SO2, SO3, amino, mono- and di-(C1-C24) alkyl substituted amino, mono- and di-(C5-C20) aryl substituted amino, imino, phosphono, phosphonato, phosphinato, phospho, phosphino, a branched, unbranched, saturated or unsaturated 1-30C hydrocarbon group which may have suitable substituents and the hydrocarbon group may have one or more heteroatoms in the chain, aryl or heteroaryl group which can have suitable substituents, each of R2, R3 and R4 can form a 5- or 6-membered ring or annelated 5-and/or 6-membered rings which can be aromatic, alicyclic, heteroaromatic or heteroalicyclic and have up to 4 substituents, are reacted with a hybrid donor to form a compound of general formula (II) in which R1, R2, R3 and R4 are as above. Said method permits the selective hydrogenation of a,? unsaturated aldehydes and ketones without the use of metal catalysts.
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Page/Page column 11
(2008/06/13)
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- Arenediazonium o-benzenedisulfonimides in Heck-type arylation of allylic alcohols
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Arenediazonium o-benzenedisulfonimides were reacted with primary and secondary allylic alcohols. The reactions, carried out in aqueous ethanol in the presence of palladium(II) acetate as precatalyst and sodium hydrogen carbonate as base, gave the arylation products with good overall conversion. In all cases, the major products were the β-arylated carbonyl derivatives. The o-benzene-disulfonimide was recovered in high yield from all the reactions, and it was recycled for the preparation of other salts. Georg Thieme Verlag Stuttgart.
- Barbero, Margherita,Cadamuro, Silvano,Dughera, Stefano
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p. 3443 - 3452
(2008/02/12)
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- A metal-free transfer hydrogenation: Organocatalytic conjugate reduction of α,β-unsaturated aldehydes
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Impressive tolerance is displayed in the efficient and chemoselective organocatalytic transfer hydrogenation of α,β-unsaturated aldehydes in the presence of a Hantzsch dihydropyridine and a catalytic amount of dibenzylammonium trifluoroacetate (see scheme). Various sensitive functional groups such as the nitro, cyano, alkenyl, and benzyloxy groups survive these reaction conditions.
- Yang, Jung Woon,Hechavarria Fonseca, Maria T.,List, Benjamin
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p. 6660 - 6662
(2007/10/03)
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- Photochemical synthesis of aldehydes in the solid phase
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A substituted anthraquinone (AQ), previously shown to photochemically generate benzaldehyde in methanol solution, was attached to a commercially available resin via an 11 carbon tether and an amide bond. Photolysis of the polymer-bound AQ with visible or 350 nm UV light resulted in the formation of benzaldehyde in yields of 50-55% as determined by HPLC. The phenolic positions in the polymer were then alkylated using benzyl bromide and 1-iodo-3-(4-nitrophenyl)propane in a coupling reaction with K2CO3 as a base and a solution-phase proton shuttle. Photolysis of these alkylated polymers resulted in the formation of benzaldehyde (54-89%) and 3-(4-nitrophenyl)-propanal (58-67%). The yields of both aldehydes dropped considerably with subsequent realkylation and photolysis, and the polymer beads began to show signs of deterioration. This is the first time that aldehydes have been made photochemically on a solid-supported phase.
- Blankespoor, Ronald L.,DeVries, Tim,Hansen, Eric,Kallemeyn, Jeffrey M.,Klooster, Aaron M.,Mulder, Jason A.,Smart, Robert P.,Vander Griend, Douglas A.
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p. 2677 - 2681
(2007/10/03)
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- Homogeneous Catalytic Hydroformylation of Vinylarenes: A Selective Rhodium Diphosphine Catalyst System for Higher Branched/Linear Product Ratios
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A rhodium diphosphine catalyst containing electron-withdrawing substituents on the ligand is highly regioselective in the hydroformylation of vinylarenes giving high branched/linear product ratios.
- Chan, Albert S. C.,Pai, Cheng-Chao,Yang, Teng-Kuei,Chen, Shih-Min
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p. 2031 - 2032
(2007/10/02)
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- Asymmetric Hydroformylation Catalyzed by Homogeneous and Polymer-Supported Platinum Complexes Containing Chiral Phosphine Ligands
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A complex of Pt(II) containing the chiral ligand (2S,4S)-N-(tert-butoxycarbonyl)-4-(diphenylphosphino)-2-pirrolidine in the presence of stannous chloride catalyzed the hydroformylation of a variety of prochiral olefins.Although the branched/normal (b/n) ratios were low (ca. 0.5), high ee's were achieved in the hydroformylation of styrene (70-80percent), p-isobutylstyrene (80percent), 2-vinylnaphthalene (77percent), 2-ethenyl-6-methoxynaphthalene (81percent), 4-(2-thienylcarbonyl)styrene (78percent), vinyl acetate(82percent), N-vinylphthalimide (73percent), methyl methacrylate (60percent), and norbornene (60percent).When the hydroformylation of styrene, 2-ethenyl-6-methoxynaphthalene, and vinyl acetate with PtCl2/SnCl2 was carried out in the presence of triethyl orthoformate, enantiomerically pure acetals were obtained.The hydroformylation in the presence of ethyl orthoformate also could be carried out by using a catalyst containing the PtCl2/SnCl2 complex bound to 60-μm beads composed of cross-linked polystyrene.
- Parrinello, Giovanni,Stille, J. K.
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p. 7122 - 7127
(2007/10/02)
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- ORGANO TIN NUCLEOPHILES IV. PALLADIUM CATALYZED CONJUGATE REDUCTION WITH TIN HYDRIDE
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Highly chemoselective conjugate reduction of α,β-unsaturated carbonyl compounds is now possible by using tributyl tin hydride with ; an optimization study puts forth the importance of added radical scavenger and proton source in these reductions.
- Keinan, Ehud,Gleize, Pierre A.
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p. 477 - 480
(2007/10/02)
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