- C3-Thioester/-Ester Substituted Linear Dienones: A Pluripotent Molecular Platform for Diversification via Cascade Pericyclic Reactions
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Substituted oxabicyclo derivatives bearing two quaternary carbon centers and five contiguous stereocenters have been synthesized from C3-thioester/-ester substituted dienones, a simple and linear pluripotent molecular platform. The conversion proceeds from neat reactants, possibly via a thermally-driven pericyclic cascade manifold involving sequential (E)-s-trans to (E)-s-cis isomerization, oxa-6π-electrocyclization, and intermolecular, regioselective [4π+2π] cycloaddition. The proposed mechanism has been substantiated by intermediate trapping experiments and DFT studies. Such dienones have also been exploited to effect stereoselective cross Diels-Alder cycloadditions with olefins and sequential Diels-Alder/retro-Diels-Alder reactions with activated alkynes. The reaction is greatly influenced by the substituent effect exerted by the C3-thioester/-ester group. (Figure presented.).
- Bankura, Abhijit,Naskar, Sandip,Roy Chowdhury, Sabyasachi,Maity, Rajib,Mishra, Sabyashachi,Das, Indrajit
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- Synthesis and characterization of cinnamylidene acetone – A study on tuning of band gap by vibrational spectroscopic tools
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The title molecule Cinnamylidene acetone (CA) was synthesized through a single step base catalyzed aldol type condensation between acetone and cinnamaldehyde. The prepared molecule has been characterized using NMR (1H and 13C) spectral analysis, FTIR, UV–Vis and Elemental analysis. The complete vibrational characterization of the molecule was performed using experimental (FTIR and FT-Raman) spectra and calculations at DFT level. In order to carry out a detailed vibrational spectroscopic analysis of CA, Fourier Transform Infrared and Fourier Transform Raman spectra recorded in condensed phase were used. To determine the optimized geometry and vibrational wavenumbers, Density functional theory calculations in the B3LYP/6-31G** level have been carried out followed by scaling using the scaled quantum mechanical methodology. A root mean square deviation of 6.53 cm?1 has resulted from the scaled quantum mechanical treatment. The ultraviolet visible spectra of the title compound dissolved in various solvents were recorded in the range of 300–600 nm. The natural bond orbital and frontier molecular orbital analyses were also performed using B3LYP/6-31G** method. These studies revealed a reduction in the band gap of CA in comparison with that of cinnamaldehyde (CY).
- Ragavendran,Muthunatesan,Santhanam,Arsic, Biljana
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- Direct Catalytic Asymmetric Synthesis of Disubstituted 4-Oxocyclohexanecarbaldehydes from Acetone and Cinnamaldehyde Derivatives
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A first catalytic asymmetric reaction of acetone with cinnamaldehyde for the synthesis of disubstituted 4-oxocyclohexanecarbaldehyde is developed. A variety of substituted cinnamaldehydes are successfully tested under the optimized reaction conditions. Both the enantiomers of the same diastereomeric products are achieved in good yield and diastereoselectivity with an excellent enantioselectivity by changing the enantiomer of one of the two chiral catalysts. The practicality of this methodology is demonstrated by the gram-scale synthesis.
- Maurya, Vidyasagar,Kutwal, Mahesh S.,Appayee, Chandrakumar
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- Hydroperoxidations of Alkenes using Cobalt Picolinate Catalysts
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Hydroperoxides were synthesized in one step from various alkenes using Co(pic)2as the catalyst with molecular oxygen and tetramethyldisiloxane (TMDSO). The hydration product could be obtained using a modified catalyst, Co(3-mepic)2, with molecular oxygen and phenylsilane. Formation of hydroperoxides occurred through a rapid Co-O bond metathesis of a peroxycobalt compound with isopropanol.
- Peralta-Neel, Zulema,Woerpel
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supporting information
p. 5002 - 5006
(2021/06/30)
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- Diastereodivergent synthesis of 4-oxocyclohexanecarbaldehydes by using the modularly designed organocatalysts upon switching on their iminium catalysis
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The cinchona thiourea moiety in the self-assembled modularly designed organocatalysts (MDOs) switches off the iminium catalysis of these catalysts. In this study, it was found that the inhibited iminium catalysis could be switched on by using an appropriate weak acid and that, once the iminium catalysis was switched on, these catalysts could be applied for the highly stereoselective and diastereodivergent synthesis of 4-oxocyclohexanecarbaldehydes via a domino reaction between ketones and α,β-unsaturated aldehydes. This journal is
- Bora, Pranjal,Jakkampudi, Satish,Parella, Ramarao,Sakkani, Nagaraju,Dai, Qipu,Bihani, Manisha,Arman, Hadi D.,Zhao, John C.-G.
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supporting information
p. 5334 - 5337
(2021/06/06)
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- Palladium-Catalyzed Aminomethylation of Nitrodienes and Dienones via Double C—N Bond Activation
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A new strategy for the generation of the active Pd-alkyl species from aminal via C—N bond activation has been established, in which the formation of zwitterionic intermediate through aza-Michael addition of aminal to nitrodienes or dienones is identified as a key step for the activation of the C—N bond. The efficient strategy has enabled a new palladium-catalyzed α-aminomethylation of nitrodienes and dienones via double C—N bond activation. The scope and versatility of the reaction were demonstrated and a broad range of substrates bearing electron-donating and -withdrawing groups on the aromatic rings were all compatible with this reaction to furnish the desired α-aminomethylated products in moderate to good yields with excellent regioselectivities and E/Z selectivities.
- Yu, Bangkui,Gao, Bao,Zhang, Xuexia,Zhang, Haocheng,Huang, Hanmin
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supporting information
p. 566 - 570
(2021/02/01)
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- SYNTHESIS, CRYSTAL STRUCTURE, AND BIOLOGICAL ACTIVITY OF NOVEL CURCUMIN ANALOGUES DERIVED FROM CINNAMALDEHYDE
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Abstract: A series of novel trienone curcumin analogues 1, based on Claisen–Schmidt condensations of cinnamaldehyde, arylaldehyde, and acetone, is prepared and the crystal structure of 1a is determined by single crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group P21/c with a?=?18.120(5)??, b?=?14.624(4)??, c?=?5.8926(16)??, β?=?97.686(3)°, Z?=?4, V?=?1547.3(7)??3, Dc?=?1.265?mg/m3, μ?=?0.243?mm–1, F(000)?=?616, final R?=?0.0449 and wR?=?0.1109 for 2156 observed reflections (I?>?2σ(I)). In addition, molecular docking of compounds 1a, 1d and IKKβ protein are performed in CDOCKER of Discovery Studio 4.5 and the three-dimensional crystal structures of the cancer factor-human kinase-β enzyme IKKβ (PDB: 4KIK) are obtained. Furthermore, the antitumor activities of 1a and 1d are evaluated by the CCK-8 assay against human cancer cell line A549 in vitro, indicating that the small molecules have a moderate antitumor activity.
- Cui, H. F.,Lin, Y.,Liu, W. Q.,Lu, B.,Ren, S. H.,Wan, P. N.
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p. 1123 - 1130
(2021/08/17)
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- Relay Catalysis to Synthesize β-Substituted Enones: Organocatalytic Substitution of Vinylogous Esters and Amides with Organoboronates
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Organocatalysis was shown to facilitate conjugate additions to vinylogous esters and amides for the first time. Subsequent elimination of a β-alcohol or amine provided π-conjugated β-substituted enones. Remarkably, nucleophile addition to the electron-rich vinylogous substrates is more rapid than classical enones, forming monosubstituted products. A doubly organocatalytic (organic diol and methyl aniline) conjugate addition synthesized the products directly from alkynyl ketones. Both of these catalytic transformations are orthogonal to transition metal catalysis, allowing for good yields, easily accessible or commercially available reagents, high selectivity, reagent recovery and recyclability, facile scalability, and exceptional functional group tolerance.
- Sundstrom, Sasha,Nguyen, Thien S.,May, Jeremy A.
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supporting information
p. 1355 - 1359
(2020/02/13)
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- Catalytic Enantioselective Conjugate Addition of Stereodefined Di- and Trisubstituted Alkenylaluminum Compounds to Acyclic Enones
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Catalytic enantioselective conjugate addition (ECA) reactions with readily accessible and stereochemically defined E-, Z-, di- and trisubstituted alkenyl aluminum compounds are disclosed. Transformations are promoted by various NHC-copper catalysts (NHC=N-heterocyclic carbene), which are derived from enantiomerically pure sulfonate imidazolinium salts. The desired products were obtained in up to 89% yield and >99:1 e.r.; the alkenyl moiety was transferred with complete retention of its stereochemical identity in all instances. The scope and limitations of the approach, key mechanistic attributes, and representative functionalization are presented as well. (Figure presented.).
- McGrath, Kevin P.,Hubbell, Aran K.,Zhou, Yuebiao,Santos, Damián Padín,Torker, Sebastian,Romiti, Filippo,Hoveyda, Amir H.
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supporting information
p. 370 - 375
(2019/12/24)
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- The construction of novel and efficient hafnium catalysts using naturally existing tannic acid for Meerwein-Ponndorf-Verley reduction
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The conversion of carbonyl compounds into alcohols or their derivatives via the catalytic transfer hydrogenation (CTH) process known as Meerwein-Ponndorf-Verley reduction is an important reaction in the reaction chain involved in biomass transformation. The rational design of efficient catalysts using natural and renewable materials is critical for decreasing the catalyst cost and for the sustainable supply of raw materials during catalyst preparation. In this study, a novel hafnium-based catalyst was constructed using naturally existing tannic acid as the ligand. The prepared hafnium-tannic acid (Hf-TA) catalyst was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetry (TG). Hf-TA was applied in the conversion of furfuraldehyde (FD) to furfuryl alcohol (FA) using isopropanol (2-PrOH) as both the reaction solvent and the hydrogen source. Both preparation conditions and the effects of the reaction parameters on the performance of the catalyst were studied. Under the relatively mild reaction conditions of 70 °C and 3 h, FD (1 mmol) could be converted into FA with a high yield of 99.0%. In addition, the Hf-TA catalyst could be reused at least ten times without a notable decrease in activity and selectivity, indicating its excellent stability. It was proved that Hf-TA could also catalyze the conversion of various carbonyl compounds with different structures. The high efficiency, natural occurrence of tannic acid, and facile preparation process make Hf-TA a potential catalyst for applications in the biomass conversion field.
- Deng, Lijuan,Hao, Jianxiu,He, Runxia,Li, Na,Liu, Quansheng,Wang, Xiaolu,Zhao, Hongye,Zhi, Keduan,Zhou, Huacong
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p. 6944 - 6952
(2020/03/03)
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- Ru-Catalyzed Chemo- And Enantioselective Hydrogenation of 2,4-Pentadien-1-ones: Synthesis of Chiral 2,4-Pentadien-1-ols
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The asymmetric hydrogenation of 2,4-pentadien-1-ones has been achieved by using trans-RuCl2[(R)-XylylSunPhos][(R)-Daipen] as a catalyst under basic conditions. This hydrogenation demonstrated exclusive C1-carbonyl selectivity, and thus the conjugated 2,4-diene motifs remained untouched, which provides a synthetically useful method for various chiral 2,4-pentadien-1-ols.
- Li, Chengyang,Lu, Wenkui,Lu, Bin,Li, Wanfang,Xie, Xiaomin,Zhang, Zhaoguo
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p. 16086 - 16094
(2019/12/24)
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- One-Pot Synthesis of Metastable 2,5-Dihydrooxepines through Retro-Claisen Rearrangements: Method and Applications
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A one-pot methodology to synthesize metastable bicyclic 2,5-dihydrooxepines from cyclic 1,3-diketones and 1,4-dibromo-2-butenes through the retro-Claisen rearrangement of syn-2-vinylcyclopropyl diketone intermediates is reported. DFT calculations were performed to understand the reaction selectivity and mechanisms towards [1,3]- or [3,3]-sigmatropic rearrangements, highlighting the crucial influence of the temperature. The reaction was successfully applied to a short protecting group-free total synthesis of radulanin A, a natural 2,5-dihydrobenzoxepine. Moreover, the strong herbicidal potential of this natural product is demonstrated for the first time.
- Zhang, Wei,Baudouin, Emmanuel,Cordier, Marie,Frison, Gilles,Nay, Bastien
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supporting information
p. 8643 - 8648
(2019/07/16)
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- Boehmite - An efficient and recyclable acid-base bifunctional catalyst for aldol condensation reaction
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In this work boehmite was used as an acid-base bifunctional catalyst for aldol condensation reactions of aromatic aldehydes and ketones. The catalyst was prepared by simple sol-gel method using Al(NO3)3 · 9H2O and NH4OH as precursors. The catalyst has been characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), UV-visible spectroscopy (DRS), BET surface area analyses. Boehmite is successfully applied as catalyst for the condensation reaction between 4-nitrobenzaldehyde and acetone as a model substrate giving α,β-unsaturated ketones without any side product. The scope of the reaction is extended for various substituted aldehydes. A probable mechanism has been suggested to explain the cooperative behavior of the acidic and basic sites. The catalyst is environmentally friendly and easily recovered from the reaction mixture. Also the catalyst is reusable up to 3 catalytic cycles.
- Reshma, P.C. Rajan,Vikneshvaran, Sekar,Velmathi, Sivan
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p. 4270 - 4275
(2018/01/11)
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- Gram-scale preparation of dialkylideneacetones through Ca(OH)2-catalyzed Claisen-Schmidt condensation in dilute aqueous EtOH
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A synthetic method of dialkylideneacetones has been developed. Compared with known protocols, the method employed catalytic Ca(OH)2 as the cheap, mild base catalyst and dilute aqueous EtOH (20%, v/v) as the green and safe solvent. The procedure was easily operated: In most cases, the product could be isolated by a simple filtration, and purified by washing with water. This paper provided experimental details of the reactions, which could be applied in gram-scale synthesis and should be a very reliable and practical protocol to prepare these useful compounds in laboratory and at the industrial level.
- Zhang, Hao,Han, Mengting,Yang, Chenggen,Yu, Lei,Xu, Qing
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- Construction of β to carbonyl stereogenic centres by asymmetric 1,4-addition of alkylzirconocenes to dienones and ynenones
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Copper-catalyzed asymmetric 1,4-addition of alkylzirconium species to linear α,β,γ,δ unsaturated dienones and ynenones is reported. A variety of alkyl nucleophiles are introduced with good yields and excellent regio- and enantio-selectivities to give tertiary carbon centres bearing multiple functional groups. The method is also applicable to an ynethioate with ee's over 96%.
- Gao, Zhenbo,Fletcher, Stephen P.
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supporting information
p. 3601 - 3604
(2018/04/12)
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- Iridium-catalysed desilylative acylation of 1-alkenylsilanes
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We report the iridium-catalysed desilylative acylation of styryl and dienyl silanes by acid anhydrides to afford (E)-α,β-unsaturated ketones. The [{Ir(μ-Cl)(cod)}2] catalyst is the first non-rhodium complex successfully applied for this type of
- Zaranek, Maciej,Skrodzki, Maciej,Szudkowska-Fr?tczak, Justyna,Dodot, Maciej,Kownacki, Ireneusz,Orwat, Bartosz,Pawlu?, Piotr
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- Regio- and Enantioselective Copper-Catalyzed 1,4-Conjugate Addition of Trimethylaluminium to Linear α,β,γ,δ-Unsaturated Alkyl Ketones
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A regio- and enantioselective copper-catalyzed 1,4-conjugate addition of trimethylaluminium to linear δ-aryl-substituted α,β,γ,δ-unsaturated alkyl ketones was developed. A series of γ,δ-unsaturated alkyl ketones were obtained in good yields with high regio- and enantioselectivity (up to 88% ee and 96:4 dr). Expansion of the reaction scope to substrates containing aromatic heterocycles also afforded good yields and enantioselectivities (up to 91% ee) with very high regioselectivities, exclusively providing the single 1,4-products. (Figure presented.).
- Wu, Xiaoting,Xie, Fang,Ling, Zheng,Tang, Liang,Zhang, Wanbin
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supporting information
p. 2510 - 2518
(2016/08/16)
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- Copper-catalyzed retro-aldol reaction of β-hydroxy ketones or nitriles with aldehydes: Chemo- and stereoselective access to (E)-enones and (E)-acrylonitriles
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A copper-catalyzed transfer aldol type reaction of β-hydroxy ketones or nitriles with aldehydes is reported, which enables chemo- and stereoselective access to (E)-α,β-unsaturated ketones and (E)-acrylonitriles. A key step of the in situ copper(i)-promoted retro-aldol reaction of β-hydroxy ketones or nitriles is proposed to generate a reactive Cu(i) enolate or cyanomethyl intermediate, which undergoes ensuing aldol condensation with aldehydes to deliver the products. This reaction uses 1.2 mol% Cu(IPr)Cl (IPr denotes 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) as the catalyst in the presence of 6.0 mol% NaOtBu cocatalyst at room temperature or 70 °C. A range of aryl and heteroaryl aldehydes as well as acrylaldehydes are compatible with many useful functional groups being tolerated. Under the mild and weakly basic conditions, competitive Cannizzaro-type reaction of benzaldehydes and side reactions of base-sensitive functional groups can be effectively suppressed, which show synthetic advantages of this reaction compared to classic aldol reactions. The synthetic potential of this reaction is further demonstrated by the one-step synthesis of biologically active quinolines and 1,8-naphthyridine in excellent yields (up to 91%). Finally, a full catalytic cycle for this reaction has been constructed using DFT computational studies in the context of a retro-aldol/aldol two-stage mechanism. A rather flat reaction energy profile is found indicating that both stages are kinetically facile, which is consistent with the mild reaction conditions.
- Zhang, Song-Lin,Deng, Zhu-Qin
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p. 7282 - 7294
(2016/08/05)
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- Mutual Cooperation in the Formal Allyl Alcohol Nucleophilic Substitution and Hydration of Alkynes for the Construction of γ-Substituted Ketones
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Mutual cooperation in the formal allyl alcohol nucleophilic substitution reaction and hydration of an alkyne has been utilized in the presence of a gold catalyst to give a series of γ-functionalized ketones with high to excellent yields. This reaction actually involved an intramolecular O-H insertion cyclization of an alkyne to form the dihydrofuran intermediate, which was followed by the nucleophilic addition ring-opening of a dihydrofuran to give the target compound.
- Huang, Kaimeng,Wang, Hongkai,Liu, Lingyan,Chang, Weixing,Li, Jing
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supporting information
p. 6458 - 6465
(2016/05/09)
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- Activation of Chiral (Salen)AlCl Complex by Phosphorane for Highly Enantioselective Cyanosilylation of Ketones and Enones
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Phosphoranes 2 are identified as a class of effective Lewis bases to activate chiral (salen)AlCl complex 1 to enhance its electrophilicity. Accordingly, a three-component catalyst system consisting of complex 1, phosphorane 2e, and Ph3PO is developed as a powerful tool for asymmetric ketone cyanosilylation. In particular, an unprecedented highly enantioselective cyanosilylation of linear aliphatic ketones is achieved. A tandem Wittig-cyanosilylation sequence starting from phosphorane 2a and enals 10 is further achieved, which internally utilizes the Ph3PO byproduct and remaining phosphorane 2a as cocatalysts for cyanosilylation of α,β,γ,δ-unsaturated enones, providing atom-efficient access to valuable chiral conjugated dienes and enynes. The high efficiency of the cyanosilylation originates from orthogonal activation of both (salen)AlCl complex 1 and cyanotrimethylsilane by the phosphorane and Ph3PO, respectively. This mechanistic insight is supported by NMR, MS, and ReactIR analyses and DFT calculations. Furthermore, the formation of charged complexes through the activation of chiral complex 1 by phosphorane 2a is confirmed by electrical conductivity experiments.
- Zeng, Xing-Ping,Cao, Zhong-Yan,Wang, Xin,Chen, Long,Zhou, Feng,Zhu, Feng,Wang, Cui-Hong,Zhou, Jian
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supporting information
p. 416 - 425
(2016/01/25)
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- Chemoselective biohydrogenation of α,β- and α,β,γ,δ-unsaturated ketones by the marine-derived fungus Penicillium citrinum CBMAI 1186 in a biphasic system
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To broaden the range of applicability of a reduction reaction mediated by the marine fungal strain Penicillium citrinum CBMAI 1186 to organic chemical processes, the ability of whole mycelia to grow in biphasic mixtures with organic solvents was tested with acetone, ethyl acetate, n-butanol, dichloromethane, n-hexane and toluene. n-Hexane was the least toxic solvent according to the amount of mycelial mass grown in an artificial sea water medium mixed with each solvent. Therefore, whole hyphae of P. citrinum CBMAI 1186 were used as biocatalysts in the chemoselective biotransformation of the carbon-carbon double bond in α,β-, di-α,β-, and mono-α,β,γ,δ-unsaturated ketones (3a, 3c-f) in a biphasic system of phosphate buffer and n-hexane (9:1). Only the di-α,β,γ,δ-unsaturated ketone (3b) was not biocatalyzed under these conditions. In general, there were good conversions of saturated ketones by the enoate reductase enzymes of P. citrinum CBMAI 1186.
- Ferreira, Irlon M.,Meira, Eloá B.,Rosset, Isac G.,Porto, André L.M.
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- Synthesis of Polysubstituted Pyridines via a One-Pot Metal-Free Strategy
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An efficient strategy for the one-pot synthesis of polysubstituted pyridines via a cascade reaction from aldehydes, phosphorus ylides, and propargyl azide is reported. The reaction sequence involves a Wittig reaction, a Staudinger reaction, an aza-Wittig reaction, a 6π-3-azatriene electrocyclization, and a 1,3-H shift. This protocol provides quick access to the polysubstituted pyridines from readily available substrates in good to excellent yields.
- Wei, Hongbo,Li, Yun,Xiao, Ke,Cheng, Bin,Wang, Huifei,Hu, Lin,Zhai, Hongbin
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supporting information
p. 5974 - 5977
(2016/01/09)
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- Synthesis of substituted fluorenes by cascade allenylation, electrocyclization and intramolecular friedel-crafts reaction of 1,3-diene-substituted propargylic alcohols
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A concise, one-step synthesis of substituted fluorenes through TiCl 4-promoted cascade allenylation, electrocyclization and intramolecular Friedel-Crafts reaction of 1,3-diene-substituted propargylic alcohols has been developed. An interesting substituent-dependent regioselectivity was observed.
- Xu, Xiangsheng,Li, Tao,Li, Xiaoqing,Shao, Jiangbin
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p. 383 - 388
(2013/04/23)
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- Synthesis and neuroprotective effect of E-3,4-dihydroxy styryl aralkyl ketones derivatives against oxidative stress and inflammation
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E-3,4-Dihydroxy styryl aralkyl ketones as well as their 3,4-diacetylated derivatives as the analogues of neuroprotective agent CAPE were designed and synthesized for improving stability and lipid solubility. The neuroprotective activities of target compounds 10a-g and 11a-g were tested by three models in vitro, including 1,1-diphenyl-2-picrylhydrazyl radical scavenging capacity, neuronal protecting effect against damage induced by H2O2 in PC12 cells and nitric oxide suppression effect in BV2 microglial cells. The results demonstrated that compounds 10f and 11f exhibited the most potent neuroprotective effect against oxidative stress and inflammation, which is higher than that of the lead compound CAPE.
- Ning, Xianling,Guo, Ying,Ma, Xiaoyan,Zhu, Renzong,Tian, Chao,Wang, Xiaowei,Ma, Zhizhong,Zhang, Zhili,Liu, Junyi
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p. 3700 - 3703
(2013/07/25)
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- Microwave-assisted convenient synthesis of α,β-unsaturated esters and ketones via aldol-adduct elimination
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Various fluorinated 3-oxo ester/1,3-diketones were reacted with carbonyl compounds, in presence of piperidine and under microwave irradiation, to afford (E)-α,β-unsaturated esters and ketones in good yields. The systematic study reveals that the reaction proceeded through the formation of aldol adduct. The method provides a new and simple way for C,C bond formations. Copyright
- Suman, Pathi,Nageswara Rao, Rayala,China Raju, Bhimapaka
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p. 1548 - 1559
(2013/09/02)
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- Aldol reactions mediated by a tetrahedral boronate
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The base is a key factor in aldol reactions in organic media, determining the selectivity. Here, we describe a tetrahedral phenylboronate salt as a mild non-nucleophilic base that is able to catalyse the aldol reaction and significantly decrease the formation of undesired elimination products. This journal is
- Mueller, Tobias,Djanashvili, Kristina,Arends, Isabel W.C.E.,Peters, Joop A.,Hanefeld, Ulf
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supporting information
p. 361 - 363
(2013/02/23)
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- Aldol condensations of aldehydes and ketones catalyzed by primary amine on water
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Potassium glycinate-catalyzed aldol condensation reactions of aromatic aldehydes and ketones on water at room temperature have been developed. Under optimal conditions, various condensation adducts are furnished in up to 63 % yield. By simple separation of the oil phase, potassium glycinate-containing water is reused to catalyze aldol condensation for six runs without loss of catalytic activity. Theoretical investigation reveals correlation between the yields and dehydroxylation energy barriers of aldol products, reasonably low activation energy of 11.9 kcal/mol for transition state formation in condensation of benzaldehyde and acetone, vibrations between aldol donor and acceptor, which correspond to the only imaginary frequency (-179.8i).
- Zhang, Xu,Xiong, Yan,Zhang, Shuting,Ling, Xuege,Wang, Jinyue,Chen, Changguo
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experimental part
p. 751 - 755
(2012/07/28)
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- Tandem aldol condensation/platinacycle-catalyzed addition reactions of aldehydes, methyl ketones, and arylboronic acids
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Aldol condensation of aldehydes with methyl ketones followed by anionic four-electron donor-based (type I) platinacycle-catalyzed addition reactions of arylboronic acids to form β-arylated ketones is described. Good to excellent yields of β-arylated ketones were obtained for the tandem reactions of aromatic/aliphatic aldehydes, methyl ketones, and arylboronic acids, and moderate yields were observed for the tandem reactions of α,β-unsaturated aldehydes. The aldol condensation of aldehydes with methyl ketones was successfully combined with the platinacycle-catalyzed addition reactions of arylboronic acids in a tandem fashion. A variety of β-arylated ketones was obtained in good to excellent yields.
- Liao, Yuan-Xi,Hu, Qiao-Sheng
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p. 5897 - 5901,5
(2020/09/02)
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- Stereoselective olefination of N-sulfonyl imines with stabilized phosphonium ylides for the synthesis of electron-deficient alkenes
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An unprecedented protocol has been developed for thestereoselective synthesis of structurally diverse electron-deficient alkenes in moderate to excellent yields from readily accessible N-sulfonyl imines and stabilized phosphonium ylides. Significantly, the olefination reaction of N-sulfonylimines with nitrile-stabilized phosphonium ylides affords an array of α,β-unsaturated nitriles with high Z selectivity, and the reactions with ester-, amide-, and ketone-stabilized phosphonium ylides afford α,β-unsaturated esters, amides, and ketones with high E selectivity, respectively. Spectroscopic analysis of the reaction mixtures and trapping of the intermediates allow plausible mechanisms to be proposed. Initialimine/ylide addition leads to the formation of betaines that cyclize to form 1,2-azaphosphetanes that subsequently eliminate iminophosphoranes to yield alkenes. For the synthesis of electron-deficient 1,2-disubstituted alkenes, the presence of an electron-withdrawing group in the betaine allows rapid interconversion between its two diastereomers through proton transfer. The Z/E selectivity for alkene synthesis is determined by the different rates at which the two betaine diastereomers form the corresponding 1,2-azaphosphetane diastereomers. In contrast, the Z/E selectivity for the synthesis of electron-deficient trisubstituted alkenes originates from the diastereoselective addition of stabilized phosphonium ylides to N-sulfonyl imines.
- Fang, Fan,Li, Yuan,Tian, Shi-Kai
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experimental part
p. 1084 - 1091
(2011/04/15)
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- A convenient route to (E)-α,β-unsaturated methyl ketones
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Aldehydes are converted into (E)-α,β-unsaturated methyl ketones in good yield and with a high E stereoselectivity using α,α- bis(trimethylsilyl) N-tert-butyl acetimine 3. The reaction was mediated by a catalytic amount of tetrabutylammonium fluoride (TBAF) under mild conditions. The disilylated reagent 3 is easily generated from N-tert-butylacetimine, lithium diisopropylamide (LDA), and chlorotrimethylsilane. The mechanism of the reaction is discussed. Copyright
- Bellassoued,Aatar,Bouzid,Damak
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experimental part
p. 1886 - 1895
(2010/11/18)
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- Chromatography-free wittig reactions using a bifunctional polymeric reagent
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The first example of a polystyrene bearing two distinct reagent groups has been prepared. This phosphine and amine functionalized material was used in one-pot Wittig reactions with an aldehyde and either an α-halo-ester, -ketone, or -amide. Due to the heterogeneous nature of the polymer, the desired alkene product of these reactions could be isolated in excellent yield in essentially pure form after only filtration and solvent removal.
- Leung, Peter Shu-Wai,Teng, Yan,Toy, Patrick H.
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supporting information; experimental part
p. 4996 - 4999
(2010/12/25)
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- A concise and efficient way to synthesize polyenic diones directly from α,β-unsaturated methyl ketones
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A concise and efficient approach to polyenic compounds containing important diketone structural fragments is developed from readily available α,β-unsaturated methyl ketones in the presence of copper(II) oxide, iodine, and dimethyl sulfoxide. This is a new carbon-carbon double bond-forming reaction from two methyl sp3 C-H bonds and an attractive route to introduce the SMe group into the molecule from inexpensive dimethyl sulfoxide. The hypothetic self-sorting tandem reaction mechanism is also proposed in this paper.
- Gao, Meng,Yin, Guodong,Wang, Zihua,Wu, Yandong,Guo, Cheng,Pan, Yuanjiang,Wu, Anxin
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supporting information; experimental part
p. 6047 - 6049
(2011/03/19)
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- Pd(0) or Pd(II)-catalyzed ring-opening reactions of benzylidene- and alkylidenecyclopropyl ketones and aldehydes
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Pd(0) catalyzed reactions of methylenecyclopropyl carbonyl compounds afforded a convenient method for the synthesis of conjugate (E,E)-1,3-diene derivatives 2 in good to excellent yields. Moreover, we also found that Pd(II)-catalyzed reactions of methylen
- Tang, Xiang-Ying,Shi, Min
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supporting information; experimental part
p. 8863 - 8868
(2009/12/26)
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- Stereoseleetive synthesis of polysubstituted alkenes through a phosphine-mediated three-component system of aldehydes, α-halo carbonyl compounds, and terminal alkenes
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A study was conducted to demonstrate stereoselective synthesis of polysubstituted alkenes through a phosphine-mediated three-component system of aldehydes, α-halo carbonyl compounds, and terminal alkenes. Triphenylphosphine, α-halo carbonyl compounds, and methyl acrylate were added to a solution of aldehyde in chloroform or 1-propanol under nitrogen at room temperature. The resulting mixture was stirred at the specified temperature until transformation was completely observed by thin layer chromatography (TLC) analysis. The mixture was cooled to room temperature and purified by column chromatography on silica gel, eluting with petroleum ether/ethyl acetate. The study demonstrated that the first one-pot and three-component reaction of aldehydes, α-haloacetates, and terminal alkenes was developed in the presence of phenylphosphine to produce a wide range of trisubstituted alkenes with significant stereoselectivity.
- Liu, Da-Neng,Tian, Shi-Kai
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supporting information; experimental part
p. 4538 - 4542
(2009/12/25)
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- Palladium-tetraphosphine complex catalysed heck reaction of vinyl bromides with alkenes: A powerful access to conjugated dienes
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A wide variety of 1,3-dienes have been prepared by the Heck vinylation of vinyl bromides using [Pd(η3-C3H5)Cl] 2/cis,cis,cis-1,2,3,4-tetrakis[(diphenylphosphino)methyl] cyclopentane (Tedicyp) as the catalyst precursor. Both α- and β-substituted vinyl bromides undergo the Heck reaction with functionalised alkenes such as acrylates, enones, styrenes or a vinyl sulfone, and also with nonfunctionalised alkenes such as dec-1-ene, leading stereoselectively, in most cases, to the corresponding E- or E,E-1,3-dienes in good yields. Furthermore, this catalyst can be used at low loading for several reactions. Georg Thieme Verlag Stuttgart.
- Lemhadri, Mhamed,Battace, Ahmed,Berthiol, Florian,Zair, Touriya,Doucet, Henri,Santelli, Maurice
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p. 1142 - 1152
(2008/12/22)
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- An efficient method for the selective iodination of ?±,?2- unsaturated ketones
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An efficient approach to ?±,?2-unsaturated ?±'-iodo ketones directly from ?±,?2-unsaturated ketones by selective iodination at the ?±'-position, without effect on the double bond and the activated benzene ring, in the presence of copper (II) oxide/iodine is described. The present method has the advantages of high yields, short reaction times, inexpensive reagents, mild reaction conditions, ease of manipulation, and the formation of cleaner products. ? Georg Thieme Verlag Stuttgart ?· New York.
- Wang, Zihua,Yin, Guodong,Qin, Jing,Gao, Meng,Cao, Liping,Wu, Anxin
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experimental part
p. 3675 - 3681
(2009/06/18)
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- Palladium-catalyzed dienylations of chelated enolates
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Isomerization-free reactions of dienyl carbonates with chelated amino acid ester enolates at -78 °C provide important information concerning the mechanism of these dienylations. The formation of regioisomeric products can be explained by competing SN2/SN2′ reactions, and the product distribution can be influenced by the proper choice of the reaction conditions. Chiral allylic substrates show a significant transfer of chirality. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Basak, Sankar,Kazmaier, Uli
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supporting information; experimental part
p. 4169 - 4177
(2009/05/30)
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- A catalytic aldol reaction and condensation through in situ boron "ate" complex enolate generation in water
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(Chemical Equation Presented) Cooperation is key: N-Butyl-1-benzimidazole- 2-phenylboronic acid hydroxide complex catalyzes the aldol condensation and aldol addition between hydroxyacetone or acetone, and different aldehydes in water. The catalytic activity results from cooperative interactions between the boronate complex and the imidazole function. Aldol condensation gives the unsaturated methyl ketones of acetone, whereas aldol addition predominates with hydroxyacetone.
- Aelvoet, Karel,Batsanov, Andrei S.,Blatch, Alexandrea J.,Grosjean, Christophe,Patrick, Leonard G. F.,Smethurst, Christian A.,Whiting, Andrew
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p. 768 - 770
(2008/12/20)
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- Tandem olefin metathesis-elimination reactions. A new route to doubly unsaturated carbonyl derivatives
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Cross-metathesis between an activated olefin and an ethereal derivative of homoallylic alcohols leads to products that are subject to facile elimination resulting in α,β,γ,δ-unsaturated esters, ketones, acids, and aldehydes in high yields.
- Lipshutz, Bruce H.,Ghorai, Subir,Bo?kovi?, ?arko V.
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p. 6949 - 6954
(2008/09/20)
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- N-vinylpyridinium and -ammonium tetrafluoroborate salts: New electrophilic coupling partners for Pd(0)-catalyzed suzuki cross-coupling reactions
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N-Vinylpyridinium and -trialkylammonium tetrafluoroborate salts represent a new class of electrophilic coupling partner for Pd(0)-catalyzed Suzuki cross-coupling reactions and give very good to excellent yields of products with a wide range of boronic acids. The salts are easily prepared from activated acetylenes and pyridinium or trialkylammonium tetrafluoroborates to form crystalline, air-stable, and nonhygroscopic crystals.
- Buszek, Keith R.,Brown, Neil
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p. 707 - 710
(2007/10/03)
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- Efficient access to conjugated dienones and diene-diones from propargylic alcohols and enolizable ketones: A tandem isomerization/condensation process catalyzed by the sixteen-electron allyl-ruthenium(II) complex [Ru(η3-2-C3H4Me)(CO)(dppf)] [SbF 6]
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A large variety of conjugated dienones R1R2C=CHCH= C(R3)C(=O)R4 and diene-diones R1R 2C=CHCH=C{C(=O)R3}C(=O)R4 have been synthesized in high yields by reacting terminal propargylic alcohols HO=CCR 1R2COH) with enolizable ketones R3CH 2C(=O)R4 and β-dicarbonyl compounds R 3C(=O)CH2C(=O)R4, respectively. The process, which is catalyzed by the 16e- (η3-allyl)- ruthenium(II) complex [Ru(η3-2-C3H4Me)(CO) (dppf)] [SbF6] associated with CF3CO2H, involves the initial isomerization of the propargylic alcohol into the corresponding α,β-unsaturated aldehyde R1R 2C=CHCHO (Meyer-Schuster rearrangement) and subsequent aldol-type condensation.
- Cadierno, Victorio,Diez, Josefina,Garcia-Garrido, Sergio E.,Gimeno, Jose,Nebra, Noel
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p. 2125 - 2132
(2007/10/03)
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- Rhodium-catalyzed acylation of vinylsilanes with acid anhydrides
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A catalytic acylation of vinylsilane with acid anhydride is accomplished by the use of [RhCl(CO)2]2, in which the transmetalation between vinylsilane and rhodium(I) carbonyl complex plays a key role. The application of this acylation reaction to (1-acyloxyvinyl)silanes provides synthetic methods for α-acyloxy enones, α-diketones, and their derivatives.
- Yamane, Motoki,Uera, Kazuyoshi,Narasaka, Koichi
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p. 477 - 486
(2007/10/03)
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- Synthesis of substituted hexa-3,5-dienoic acid methyl esters from conjugated dienones
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Substituted hexa-3,5-dienoic acid methyl esters (2) were conveniently prepared in one step by 1,2-carbonyl transposition of the corresponding dienones (1) using lead(IV) acetate and boron trifluoride-diethyl ether in benzene at room temperature.
- Nongkhlaw,Nongrum,Myrboh
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p. 1300 - 1303
(2007/10/03)
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- Unsaturated oxime ethers and their use as fungicides and insecticides
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Compounds with fungicidal and insecticidal properties having formula wherein X is N or CH; Y is O, S or NR6; A is independently hydrogen, halo, cyano, (C1-C12)alkyl, or (C1-C12)alkoxy; R1and R6is independently hydrogen or (C1-C4)alkyl; R2is independently hydrogen, (C1-C12)alkyl, halo(C1-C12)alkyl, (C3-C7)cycloalkyl, (C2-C8)alkenyl, halo(C2-C8)alkenyl, (C2-C8)alkynyl, halo(C2-C8)alkynyl, aryl, aralkyl, heterocyclic, or heterocyclic(C1-C4)alkyl; R3is independently hydrogen or (C1-C4)alkyl; R4and R5is independently hydrogen, (C1-C4)alkyl, aryl, aralkyl, aryl(C2-C8)alkenyl, aryl(C2-C8)alkynyl, heterocyclic, or heterocyclic(C1-C4)alkyl wherein if one of R4and R5is hydrogen or (C1-C4)alkyl than the other of R4and R5is other than hydrogen or (C1-C4)alkyl, and its enantiomers and stereoisomers and agronomically acceptable salts.
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- Meerwein-Ponndorf-Verley-type reductive acetylation of carbonyl compounds to acetates by lanthanide complexes in the presence of isopropenyl acetate
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Meerwein-Ponndorf-Verley-type reductive acetylation of carbonyl compounds to acetates was successfully carried out in the presence of isopropenyl acetate under the influence of a catalytic amount of Ln(O(i)Pr)3 at room temperature. Various carbonyl compounds were converted into the corresponding acetates in fair to good yields. (C) 2000 Elsevier Science Ltd.
- Nakano, Yasushi,Sakaguchi, Satoshi,Ishii, Yasutaka
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p. 1565 - 1569
(2007/10/03)
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- Wittig reactions in the ionic solvent [bmim][BF4]
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The ionic salt [bmim][BF4] is an attractive solvent for Wittig reactions, allowing both easier separation of alkenes from Ph3PO together with eficient reuse to the solvent.
- Boulaire, Virginie Le,Gree, Rene
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p. 2195 - 2196
(2007/10/03)
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- 1,8-diazabicyclo[5.4.0]undec-7-ene: A remarkable base in the epoxidation of α,β-unsaturated-δ-lactones and other enones with anhydrous t-BuOOH
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1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) has been studied for the epoxidation of electron deficient alkenes with anhydrous t-BuOOH (TBHP) in dichloroethane. Steric demands are higher than that for alkaline H2O2 DBU is recognised as a remarkable base in these oxidations as other bases such as triethyl amine, diisopropylethyl amine, and 1,4-diazabicyclo[2.2.2]octane (DABCO) are absolutely inefficient. DBU is effective in promoting the oxidation of α,β-unsaturated δ-lactones where most of conventional methods either fail or perform poor.
- Yadav,Kapoor
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p. 8573 - 8584
(2007/10/02)
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- Nickel- and Palladium-Catalyzed Aldol-Type Condensation by Enol Esters
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PdCl2(PhCN)2-SnCl2, bis(1,5-cyclooctadiene)nickel(0) /PPh3-Zn, NiBr2(PPh3)2-Zn, or Pd-(OAc)2/PPh3-Zn catalytic systems induced aldol-type condensation of isopropenyl acetate with aldehydes to produce 4-substituted (E)-3-buten-2-ones.PdCl2(PhCN)2-SnCl2 was utilized in the aldol-type reaction with any arenecarbaldehyde, bearing either an electron-donating group or an electron-withdrawing group, at 50 deg C in acetonitrile.Catalytic systems using zinc, in particular Ni(cod)2/PPh3-Zn, exhibited some high chemoselectivities at 60 deg C in dioxane: (1) an aldehyde only reacted in the presence of an internal ester or ketone, (2) olefinic aldehydes only reacted in the presence of saturated aliphatic aldehydes, (3) reactivity in the condensation with substituted benzaldehydes is the inverse of that in usual nucleophilic addition to carbonyl compound, and (4) 2-methoxybenzaldehyde only reacted in the presence of 4-methoxybenzaldehyde.Using PdCl2(PhCN)2-SnCl2, Ni(cod)2/PPh3-Zn, or Pd(OAc)2/PPh3-Zn, cyclic enol ester, namely 5-methyl-2(3H)-furanone also caused aldol-type reaction with carbonyl compounds.The reaction with Ni(cod)2/PPh3-Zn or Pd(OAc)2/PPh3-Zn at 60 deg C in dioxane selectively produced 5-substituted 4-acetyl-2(5H)-furanones via dehydrogenation of γ-substituted β-acetyl-γ-butyrolactones.
- Masuyama, Yoshiro,Sakai, Tatsuya,Kato, Takeshi,Kurusu, Yasuhiko
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p. 2265 - 2272
(2007/10/02)
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- Palladium-catalyzed aldol-type condensation by enol esters with SnCl2
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Using PdCl2(PhCN)2-SnCl2, enol esters caused aldol-type condensation with aldehydes at 50°C in acetonitrile to produce (E)-α,β-unsaturated carbonyl compounds. Cyclic enol ester such as α-angelicalactone also reacted with aldehydes under the same conditions to afford γ-substituted β-acetyle-γ-butyrolactones and/or 5-substituted 4-acetyl-2(5H)-furanones.
- Masuyama, Yoshiro,Sakai, Tatsuya,Kurusu, Yasuhiko
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p. 653 - 656
(2007/10/02)
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