- Method for synthesizing styrallyl acetate from acetophenone
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The invention provides a method for synthesizing styrallyl acetate from acetophenone, which comprises the following steps: reacting acetophenone with ketene under the catalysis of organic acid to obtain styrene acetate, and hydrogenating styrene acetate to obtain styrallyl acetate. The method is novel in synthetic route, the raw materials acetophenone and ketene are cheap and easy to obtain, the synthetic route is short, the yield is high, no equivalent acetic acid byproduct is produced, and the method has an obvious cost advantage.
- -
-
Paragraph 0033; 0036; 0063-0127
(2021/03/13)
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- Visible-Light-Promoted Synthesis of α-CF2H-Substituted Ketones by Radical Difluoromethylation of Enol Acetates
-
An efficient and novel visible-light-promoted radical difluoromethylation of enol acetates for the synthesis of α-CF2H-substituted ketones has been described. Upon irradiation under blue LED with catalytic amounts of fac-Ir(ppy)3, this photocatalytic procedure employs difluoromethyltriphenylphosphonium bromide as a radical precursor. Various α-CF2H-substituted ketones are successfully created via designed systems based on the SET process. The methodology has also provided an operationally simple process with broad functional group compatibility.
- Cheng, Li,Dong, Bingbing,Feng, Zengqiang,Li, Yunpu,Wang, Zechao,Wu, Junliang,Zhu, Baoxiang
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supporting information
p. 508 - 513
(2021/01/13)
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- Synthesis of 1,4-Dicarbonyl Compounds by Visible-Light-Mediated Cross-Coupling Reactions of α-Chlorocarbonyls and Enol Acetates
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Herein, we report a protocol for visible-light-mediated radical coupling reactions of α-chloroketones and enol acetates to afford 1,4-dicarbonyl compounds, which are important precursors and intermediates in organic synthesis. The reaction involves photoredox-catalyzed activation of the α-chloroketone upon photoelectron transfer, carbon–chlorine bond cleavage, and coupling of the resulting radical with the carbon–carbon double bond of the enol acetate. This mild protocol has a wide substrate scope and moderate to good yields. (Figure presented.).
- Liu, Qiang,Wang, Rui-Guo,Song, Hong-Jian,Liu, Yu-Xiu,Wang, Qing-Min
-
supporting information
p. 4391 - 4396
(2020/09/21)
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- Visible light induced C-H monofluoroalkylation to synthesize 1,4-unsaturated compound
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We developed a method to synthesize fluorinated 1,4-unsaturated dicarbonyl compounds via photoredox catalyzed radical addition process. Commercially available ethyl bromodifluoroacetate (BrCF2CO2Et) as fluoroalkyl source, the corresponding fluoro-containing dicarbonyl compounds could be obtained in moderate to good yields.
- Li, Wei-peng,Zhu, Yu-cheng,Zhou, Yan-jun,Yang, Hong-wei,Zhu, Cheng-jian
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p. 1647 - 1651
(2019/01/22)
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- Carboxylic acid addition to terminal alkynes utilizing ammonium tagged Hoveyda-Grubbs catalyst supported on magnetically separable core/shell silica: A highly reusable and air compatible catalytic system
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In this study, the performance of ammonium tagged Hoveyda-Grubbs catalyst supported on magnetically separable core/shell silica gel was tested on carboxylic acid addition reactions to terminal alkynes using a variety of carboxylic acid derivatives under air atmosphere. The catalytic system was found to be compatible with air atmosphere and can tolerate even non-degassed solvents. The reaction parameters such as temperature, substrate/catalyst ratio and the effect of carboxylic acid on the selectivity and yield of the reaction were investigated in details. The reaction of arylacetylenes with acetic acid yielded the corresponding E-isomer with conversion values up to 99% with a catalytic loading of 1% Ru. The reusability of the catalyst was tested using acetic acid/benzoic acid and phenylacetylene in toluene at 85 °C under air atmosphere. The catalyst was found to be highly reusable and maintained its activity up to 11th run, reaching a conversion value of 83% with minimum ruthenium leaching.
- ?ztürk, Bengi ?zgün,Gürcü, Didar,?ehito?lu, Solmaz Karabulut
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-
- Reductive Coupling between C-N and C-O Electrophiles
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The cross-electrophile reaction is a promising strategy for C-C bond formation. Recent studies have focused mainly on reactions with organic halides. Here we report a coupling reaction between C-N and C-O electrophiles that demonstrates the possibility of constructing a C-C bond via C-N and C-O cleavage. Several reactions between benzyl/aryl ammonium salts and vinyl/aryl C-O electrophiles have been studied. Preliminary mechanistic studies revealed that the benzyl ammoniums were activated through a radical mechanism.
- He, Rong-De,Li, Chun-Ling,Pan, Qiu-Quan,Guo, Peng,Liu, Xue-Yuan,Shu, Xing-Zhong
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supporting information
p. 12481 - 12486
(2019/09/04)
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- Ag2CO3-mediated direct functionalization of alkyl nitriles: Facile synthesis of γ-ketonitriles through nitrile alkylation of enol acetates
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Direct C(sp3)-H functionalization of alkyl nitriles is a low toxic and facile route to nitrile-containing compounds. In this research, the Ag2CO3-mediated nitrile methylenation of enol acetates is developed to prepare γ-ketonitriles through the direct C(sp3)-H oxidative functionalization of acetonitrile. A radical pathway is proposed, and acetonitrile serves both as solvent and CN-containing radical source.
- Cheng, Pi,Wang, Wei,Wang, Lin,Zeng, Jianguo,Reiser, Oliver,Liang, Yun
-
supporting information
p. 1408 - 1412
(2019/05/06)
-
- Porphyrins as Photoredox Catalysts in Csp2-H Arylations: Batch and Continuous Flow Approaches
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We have investigated both batch and continuous flow photoarylations of enol-acetates to yield different α-arylated aldehyde and ketone building blocks by using diazonium salts as the aryl-radical source. Different porphyrins were used as SET photocatalysts, and photophysical as well as electrochemical studies were performed to rationalize the photoredox properties and suggest mechanistic insights. Notably, the most electron-deficient porphyrin (meso-tetra(pentafluorophenyl)porphyrin) shows the best photoactivity as an electron donor in the triplet excited state, which was rationalized by the redox potentials of excited states and the turnover of the porphyrins in the photocatalytic cycle. A two-step continuous protocol and multigram-scale reactions are also presented revealing a robust, cost-competitive, and easy methodology, highlighting the significant potential of porphyrins as SET photocatalysts.
- De Souza, Aline A. N.,Silva, Nathalia S.,Müller, Andressa V.,Polo, André S.,Brocksom, Timothy J.,De Oliveira, Kleber T.
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p. 15077 - 15086
(2019/01/03)
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- Cationic ruthenium complex of the formula [RuCl(2,6-diacetylpyridine)(PPh3)2]BArF and its catalytic activity in the formation of enol esters
-
A new ruthenium 2,6-diacetylpyridine complex was synthesized and applied in the atom-economic synthesis of enol esters through Markovnikov-directed addition of carboxylic acids to terminal alkynes. The ruthenium complex [RuCl(dap)(PPh3)2]+BArF? was synthesized from [RuCl2(PPh3)2] and the corresponding ligand 2,6-diacetylpyridine (dap). The complex was characterized structurally. The new ruthenium complex was utilized under ambient conditions as a catalyst in the Markovnikov addition of carboxylic acids to terminal alkynes to afford the corresponding enol esters in 93% to 52% isolated yields (85 °C, 16 h reaction time, 1 mol% catalyst loading).
- Stark, Matthew J.,Tang, Douglas T.,Rath, Nigam P.,Bauer, Eike B.
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supporting information
p. 873 - 877
(2018/02/09)
-
- Salicylic Acid-Catalyzed Arylation of Enol Acetates with Anilines
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α-Aryl ketones are both structure moieties commonly found in bioactive compounds and versatile synthetic intermediates for the preparation of drug-like molecules. An operationally simple and scalable protocol has been developed to prepare α-aryl ketones from readily available aromatic amines and enol acetates (or silyl enol ethers). This metal-free methodology features the use of salicylic acid as a convenient catalyst to promote the formation of aryl radicals from in-situ generated aryl diazonium salts, without demanding thermal or photochemical activation. The mild reaction conditions used are compatible with anilines substituted with diverse functionalities. Structural elaboration of some prepared α-aryl ketones was accomplished to illustrate their usefulness as building blocks. (Figure presented.).
- Felipe-Blanco, Diego,Gonzalez-Gomez, Jose C.
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supporting information
p. 2773 - 2778
(2018/07/29)
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- Iron-Catalyzed Cyclization of Nitrones with Geminal-Substituted Vinyl Acetates: A Direct [4 + 2] Assembly Strategy Leading to 2,4-Disubstituted Quinolines
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An iron-catalyzed intermolecular [4 + 2] cyclization of arylnitrones with geminal-substituted vinyl acetates was developed for the synthesis of 2,4-disubstituted quinolines in moderate to good yields with good functional group compatibilities. Preliminary mechanistic studies suggest a plausible iron-catalyzed C-H activation process under external-oxidant-free conditions.
- Zhong, Mingbing,Sun, Song,Cheng, Jiang,Shao, Ying
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p. 10825 - 10831
(2016/11/29)
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- Synthesis of 1,4-Diketones from β-Oxo Esters and Enol Acetates by Cerium-Catalyzed Oxidative Umpolung Reaction
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Cyclic β-oxo esters are converted with enol acetates in a cerium-catalyzed, oxidative Umpolung reaction to furnish 1,4-diketones with up to 95 % yield. Atmospheric oxygen is the oxidant in this process, which can be regarded as ideal from economic and ecological points of view. Further advantages of this new C-C coupling reaction are its operational simplicity and the application of nontoxic and inexpensive CeCl3·7H2O as precatalyst.
- Geibel, Irina,Christoffers, Jens
-
supporting information
p. 918 - 920
(2016/03/01)
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- A family of low molecular-weight, organic catalysts for reductive C-C bond formation
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Hydrazines form a new family of low molecular-weight reducing agents for diazonium salts. Using only small amounts of hydrazine catalyst, the coupling of diazonium salts to a variety of reactive partners has been achieved, without the requirement for either metal adjuvants or irradiation with visible or ultraviolet light. The generality of the concept proposed herein as well as its advantages in the preparative scale is outlined and discussed.
- Shaaban, Saad,Jolit, Ana?s,Petkova, Desislava,Maulide, Nuno
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supporting information
p. 13902 - 13905
(2015/09/15)
-
- Iron-Catalyzed Cross-Coupling of Alkenyl Acetates
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Stable C-O linkages are generally unreactive in cross-coupling reactions which mostly employ more electrophilic halides or activated esters (triflates, tosylates). Acetates are cheap and easily accessible electrophiles but have not been used in cross-couplings because the strong C-O bond and high propensity to engage in unwanted acetylation and deprotonation. Reported herein is a selective iron-catalyzed cross-coupling of diverse alkenyl acetates, and it operates under mild reaction conditions (0 C, 2 h) with a ligand-free catalyst (1-2 mol%). Iron clad: Acetates are underutilized electrophiles in metal-catalyzed cross-coupling reactions because of the strong alkenyl C-O bond and their propensity to engage in unwanted reactions. Combination of a ligand-free low-valent Fe catalyst with nucleophilic organomagnesium reagents, low temperature, and short reaction times results in highly selective cross-couplings with alkenyl acetates.
- G?rtner, Dominik,Stein, André Luiz,Grupe, Sabine,Arp, Johannes,Von Wangelin, Axel Jacobi
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supporting information
p. 10545 - 10549
(2015/09/02)
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- Highly efficient Cu(I)-catalyzed trifluoromethylation of aryl(heteroaryl) enol acetates with CF3 radicals derived from CF3SO 2Na and TBHP at room temperature
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An efficient method for the Cu(I)-catalyzed synthesis of α-trifluoromethyl ketones via the addition of CF3 to aryl(heteroaryl) enol acetates by using the readily available CF 3SO2Na (Langlois reagent) has been developed. The reaction is experimentally simple and carried out at room temperature, providing good to excellent yields with wide functional group tolerance.
- Lu, Yang,Li, Yaming,Zhang, Rong,Jin, Kun,Duan, Chunying
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p. 128 - 133
(2014/05/06)
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- Highly enantioselective Rh-catalysed hydrogenation of 1-alkyl vinyl esters using phosphine-phosphoramidite ligands
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MatPhos, a good mate for hard tasks: The asymmetric hydrogenation of 1-alkyl vinyl esters, thwarted so far by mediocre ee values and low activities, can now be achieved with MatPhos/Rh catalysts with ee values of 96-99 % for a variety of substrates at low catalyst loadings (0.1-1 mol %) and under mild conditions (5-20 bar H2, room temperature). After hydrolysis, the corresponding chiral secondary alkyl alcohols can be obtained in high enantiopurities providing a general and practical route to this important product class. Copyright
- Konrad, Tina Maria,Schmitz, Pascal,Leitner, Walter,Francio, Giancarlo
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supporting information
p. 13299 - 13303
(2013/10/08)
-
- Modular P-OP ligands in rhodium-mediated asymmetric hydrogenation: A comparative catalysis study
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Highly efficient and enantioselective hydrogenation reactions for α-(acylamino)acrylates, itaconic acid derivatives and analogues, α-substituted enol ester derivatives, and α-arylenamides (25 substrates) catalyzed by chiral cationic rhodium complexes of a set of P-OP ligands have been developed. The catalytic systems derived from these P-OP ligands provided a straightforward access to enantiomerically enriched α-amino acid, carboxylic acid, amine, and alcohol derivatives that are valuable chiral building blocks. Excellent efficiencies (full conversion in all cases) and extremely high enantiomeric excesses (94-99% ee) were achieved for a wide range of α-substituted enol ester derivatives, regardless of the substitution pattern. The R-oxy group of the ligand (methoxy or triphenylmethoxy) strongly influences the enantioselectivity and catalytic activity. Greater steric bulk around the metal centre correlated to greater (or similar) enantioselectivity, but also to slower hydrogenation. Furthermore, the hydrogenation rates observed with the four model substrates follow the same trend, independently of the R-oxy group of the ligand: methyl 2-acetamidoacrylate>dimethyl itaconate>1-phenylvinyl acetate>N-(1- phenylvinyl)acetamide. A substrate-to-catalyst ratio (S/C) of up to 10,000:1 was sufficient for total hydrogenation of a model substrate of intermediate reactivity (dimethyl itaconate), and did not imply any loss in conversion or enantioselectivity. Copyright
- Nunez-Rico, Jose L.,Etayo, Pablo,Fernandez-Perez, Hector,Vidal-Ferran, Anton
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supporting information
p. 3025 - 3035
(2013/01/15)
-
- Visible-light-mediated α-arylation of enol acetates using aryl diazonium salts
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Visible light mediates efficiently the α-arylation of enol acetates by aryl diazonium salts under mild conditions using [Ru(bpy)3]Cl 2 as a photoredox catalyst. The broad scope of the reaction toward various diazonium salts and enol acetates was explored. The application of this reaction in the concise synthesis of 2-substituted indoles was demonstrated
- Hering, Thea,Hari, Durga Prasad,Koenig, Burkhard
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p. 10347 - 10352
(2013/01/15)
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- Copper-catalyzed enantioselective intramolecular alkene amination/intermolecular heck-type coupling cascade
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Enantioselective copper-catalyzed cyclization of γ- alkenylsulfonamides and a δ-alkenylsulfonamide in the presence of a range of vinyl arenes results in variously functionalized 2-substituted chiral nitrogen heterocycles via a formal alkene C-H functionalization process. Application of this reaction to the concise synthesis of a 5-HT7 receptor antagonist is demonstrated.
- Liwosz, Timothy W.,Chemler, Sherry R.
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supporting information; experimental part
p. 2020 - 2023
(2012/03/12)
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- InCl3/Me3SiCl-catalyzed direct michael addition of enol acetates to α,β-unsaturated ketones
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The direct Michael addition of enol acetates to α,β-unsaturated ketones was achieved using a combination of Lewis acid catalysts, InCl 3 and Me3SiCl, which furnished stable enol-form products that could be further transformed into functionalized 1,5-diketones by reactions with various electrophiles.
- Onishi, Yoshiharu,Yoneda, Yuki,Nishimoto, Yoshihiro,Yasuda, Makoto,Baba, Akio
-
supporting information
p. 5788 - 5791
(2013/01/15)
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- InCl3/Me3SiBr-catalyzed direct coupling between silyl ethers and enol acetates
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A combined Lewis acid catalyst of InCl3 and Me3SiBr promoted the direct use of enol acetates in the coupling with low-reactive silyl ethers, in which functional groups including ketones and aldehydes survived. Sterically hindered silyl ethers such as ROSiEt3, ROSiPh3, ROSit-BuMe2, and ROSii-Pr3 were also applicable.
- Onishi, Yoshiharu,Nishimoto, Yoshihiro,Yasuda, Makoto,Baba, Akio
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supporting information; experimental part
p. 2762 - 2765
(2011/08/02)
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- InI3/me3sii-catalyzed direct alkylation of enol acetates using alkyl acetates or alkyl ethers
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A combined Lewis acid of InI3 and Me3SiI was used to catalyze the direct coupling reactions of enol acetates with alkyl acetates or alkyl ethers without generating metal waste. The easily-handled alkylating reagents enlarged the application area of this coupling reaction. 2011 The Chemical Society of Japan.
- Onishi, Yoshiharu,Nishimoto, Yoshihiro,Yasuda, Makoto,Baba, Akio
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supporting information; experimental part
p. 1223 - 1225
(2011/11/29)
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- ALPHA-PENTAFLUOROSUFANYL ALDEHYDES, KETONES AND ACIDS
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Compounds of formula (I): are disclosed. In these compounds Y is -CH(OH)-, -CH(NHR6 )-, -C(=0)-, -CH=CHCO- or - formula (II) - and R1 and R2 are hydrogen, OH, alkyl, alkoxy, benzyloxy and aryl, and, when Y is -CH(OH)-, additionally alkenyl or alkynyl. Processes for the production of these compounds are also disclosed.
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Page/Page column 21
(2009/04/25)
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- Direct functionalization of benzylic C-Hs with vinyl acetates via Fe-catalysis
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Direct cross-coupling to construct sp3 C-sp3 C bonds via Fe-catalyzed benzylic C-H activation with 1-aryl vinyl acetate was developed.
- Song, Chun-Xiao,Cai, Gui-Xin,Farrell, Thomas R.,Jiang, Zhong-Ping,Li, Hu,Gan, Liang-Bing,Shi, Zhang-Jie
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supporting information; experimental part
p. 6002 - 6004
(2010/11/16)
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- Control over C-O and C-C bond formation: ruthenium catalyzed regiospecific addition of carboxylic acid to alkyne and stereoselective dimerization of alkyne
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A cationic ruthenium(II) complex, [Ru(PPh3)2(CH3CN)3Cl][BPh4] (1), has been found to be an effective catalyst for stereoselective dimerization of alkynes in the presence of a base, and for regiospecific addition of carboxylic acids to alkynes in presence of the Lewis acid, BF3·Et2O.
- Tripathy, Jyotsna,Bhattacharjee, Manish
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supporting information; body text
p. 4863 - 4865
(2009/11/30)
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- Immobilized ruthenium complexes bearing N,O-bidentate ligands
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Immobilization of a family of arene and benzylidene N,O-bidentate ruthenium complexes by covalently anchoring the homogeneous complexes on MCM-41 is described. Successful applications of these immobilized catalytic systems in enol-ester synthesis, Kharasch addition, ring-closing metathesis (RCM), ring-opening metathesis polymerization (ROMP) and atom transfer radical polymerization (ATRP) are illustrated. Important advantages of these heterogeneous catalyst systems in comparison with their homogeneous counterparts are also highlighted.
- Drǎgu?an, Valerian,Verpoort, Francis
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p. 905 - 915
(2008/09/20)
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- Regio- and stereoselective addition of carboxylic acids to phenylacetylene catalyzed by cyclopentadienyl ruthenium complexes
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The direct addition of carboxylic acids to terminal alkynes such as phenylacetylene in the presence of catalytic amount of [CpRu(CO)2Cl] (1) or [{CpRu(CO)2}2] (2) affords the anti-Markovnikov adducts with high selectivity. In most instances, the E-enol esters are the major products.
- Ye, Suming,Leong, Weng Kee
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p. 1117 - 1120
(2007/10/03)
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- Synthesis and structure of some ruthenium-rhenium heterodinuclear complexes and their catalytic activity in the addition of carboxylic acids to phenylacetylene
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The salt elimination reaction of Na[Re(CO)5] with Cp*Ru(dppm)Cl, CpRu(dppm)Cl or CpRu(CO)2Cl afforded the heterodinuclear species Cp*Ru(μ-CO)2(μ-dppm)Re(CO) 3, Cp(CO)Ru(μ-dppm)Re(CO)4, or Cp(CO) 2RuRe(CO)5, respectively, in moderate yields. An orthometallated species, Cp*(CO)Ru(μ-H)[μ-PhP(C6H 4)CH2PPh2]Re(CO)3, was also obtained from the first reaction. All these heterodinuclear products have been characterised crystallographically. They also showed good catalytic activity for the addition of carboxylic acids to phenylacetylene to afford the anti-Markovnikov products selectively.
- Ye, Suming,Leong, Weng Kee
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p. 1216 - 1222
(2007/10/03)
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- Lipase/aluminum-catalyzed dynamic kinetic resolution of secondary alcohols
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(Chemical Equation Presented) Racemization wanted: The dynamic kinetic resolution of secondary alcohols can be achieved by a simple and readily available catalyst system. Substrate racemization is effected at room temperature by a combination of (racemic) 1,1′-bi-2-naphthol (binol) or 2,2′-biphenol with AIMe3, and a lipase performs enantiospecific acylation (see scheme).
- Berkessel, Albrecht,Sebastian-Ibarz, M. Luisa,Mueller, Thomas N.
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p. 6567 - 6570
(2007/10/03)
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- Re(CO)5Br-catalyzed addition of carboxylic acids to terminal alkynes: A high anti-Markovnikov and recoverable homogeneous catalyst
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The addition of carboxylic acids to terminal alkynes is efficiently catalyzed by the early transition-metal complex Re(CO)5Br in toluene or n-heptane at 110 °C in an air atmosphere, affording the anti-Markovnikov adducts in good yields with high selectivity. In most cases, the reactions afford unusual Z-adduct predominantly. When n-heptane was used as solvent, Re(CO)5Br can be partly recovered from the reaction mixture.
- Hua, Ruimao,Tian, Xin
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p. 5782 - 5784
(2007/10/03)
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- Synthesis of enol and vinyl esters catalyzed by an iridium complex
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Enol and vinyl esters were successfully synthesized by the use of an iridium complex as a catalyst. The reaction of carboxylic acid with terminal alkynes in the presence of catalytic amounts of [Ir(cod)Cl]2 and Na2CO3 gave the corresponding 1-alkenyl esters. The addition of carboxylic acids to alkynes principally took place in the Markovnikov fashion. In addition, by the use of an Ir complex combined with NaOAc various vinyl esters were prepared through the transvinylation between carboxylic acids and vinyl acetate.
- Nakagawa, Hideto,Okimoto, Yoshio,Sakaguchi, Satoshi,Ishii, Yasutaka
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p. 103 - 106
(2007/10/03)
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- Catalytic application of a Ru-alkylidene in the nucleophilic addition of several carboxylic acids on terminal alkynes and the homo-coupling of 1-alkynes
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Thermal treatment of Ru-alkylidene (4) bearing a triazol-5-ylidene (NHC) ligand (2) at 110 °C and addition of a terminal alkyne generates a ruthenium vinylidene. The thermolysed Ru-alkylidene catalyses the vinylation and dimerisation of 1-alkynes. The nucleophilic addition of acetic acid on terminal alkynes proceeds smoothly and regioselective towards the Markovnikov addition. The addition reaction can be tuned by changing the acidity of the carboxylic acid. At increasing acidity, higher conversion of the triple bond is obtained and the vinylation/dimerisation ratio increases. The direct coupling between two 1-alkynes shows a reactivity order, which decreases from 1-octyne>1,7-octadiyne>phenylacetylene>3,3 dimethyl-1-butyne. The regioselectivity is strongly dependent on the nature of the terminal alkyne.
- Melis, Karen,De Vos, Dirk,Jacobs, Pierre,Verpoort, Francis
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p. 131 - 136
(2015/03/04)
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- Utilization of unsaturated esters as perfuming ingredients
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A compound of formula wherein the symbol R′ represents a linear or branched, unsaturated or saturated hydrocarbon group having from 1 to 5 carbon atoms; R1, R2, R3, R4 and R5 represent, independently of each other, a hydrogen atom, a methyl, an ethyl or a methoxy group; R6 and R7 represent, independently of each other, a hydrogen atom, a methyl, ethyl, n-propyl or iso-propyl group; and wherein R5 and R6, when taken together with the carbon atoms to which they are bound, may form a six-membered ring, is useful as perfuming ingredient for the preparation of perfuming compositions and perfumed products, to which it imparts odor notes of the floral and indol type without coloring problems in the final product.
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-
-
- Catalytic application of a Ru-alkylidene in the nucleophilic addition of several carboxylic acids on terminal alkynes and the homo-coupling of 1-alkynes
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Thermal treatment of Ru-alkylidene (4) bearing a triazol-5-ylidene (NHC) ligand (2) at 110°C and addition of a terminal alkyne generates a ruthenium vinylidene. The thermolysed Ru-alkylidene catalyses the vinylation and dimerisation of 1-alkynes. The nucleophilic addition of acetic acid on terminal alkynes proceeds smoothly and regioselective towards the Markovnikov addition. The addition reaction can be tuned by changing the acidity of the carboxylic acid. At increasing acidity, higher conversion of the triple bond is obtained and the vinylation/dimerisation ratio increases. The direct coupling between two 1-alkynes shows a reactivity order, which decreases from 1-octyne > 1,7-octadiyne > phenylacetylene > 3,3 dimethyl-1-butyne. The regioselectivity is strongly dependent on the nature of the terminal alkyne.
- Melis, Karen,De Vos, Dirk,Jacobs, Pierre,Verpoort, Francis
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p. 131 - 136
(2007/10/03)
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- Synthesis of enol esters and dimerization of terminal alkynes catalyzed by neutral and cationic vinylidene ruthenium complexes
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In the current study Ru(II) vinylidene complexes of the general type: Cl2Ru{=C=C(H)R}(PR′3)L (R = Ph, SiMe3, R′ = Ph, Cyclohexyl (Cy) and L = phosphine or N-heterocyclic carbene) are synthesized and tested for the addition of carboxylic acids to terminal alkynes. A careful choice of the catalytic system, substrate and carboxylic acid gives access to alk-1-en-2-yl esters, alk-1-en-1-yl esters or enyne dimerization products. Furthermore, an extension was made to synthesize an analogous 14-electron species by treating one of the complexes with AgBF4 and its influence on the catalytic activity and selectivity are investigated.
- Opstal, Tom,Verpoort, Francis
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p. 314 - 320
(2007/10/03)
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- Investigations into the regioselective C-deuteration of acyclic and exocyclic enolates
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Results are reported on the regioselective C-deuteration of a series of related acyclic and exocyclic enolates derived from substituted aryl ketones. We comment on factors, such as the presence of additives and the structural nature of the enolate, that influence the observed C-deuteration and discuss the role of the deuterium donor. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
- Eames, Jason,Coumbarides, Gregory S.,Suggate, Michael J.,Weerasooriya, Neluka
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p. 634 - 641
(2007/10/03)
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- A new heterogeneous hybrid ruthenium catalyst being an eco-friendly option for the production of polymers and organic intermediates
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We succeeded in synthesising and characterising a new heterogeneous hybrid ruthenium catalyst that exhibits excellent stability, reusability and leaching characteristics. The host-guest interaction is studied by XRD, XRF, ICP/MS, BET, FT-Raman and solid state NMR analysis. Moreover, we tested this catalytic system in ring-closing metathesis (RCM), ring-opening metathesis polymerization (ROMP), Kharasch addition, atom transfer radical polymerization (ATRP) and vinylation reactions. The results obtained from these tests show that for ROMP, RCM, Kharasch addition and vinylation reactions the heterogeneous catalyst possesses important advantages in comparison with its homogeneous analogue.
- De Clercq, Bob,Lefebvre, Frederic,Verpoort, Francis
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p. 1201 - 1208
(2007/10/03)
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- Atom transfer radical addition and enol-ester synthesis catalyzed by Ru-vinylidene complexes
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Ru-vinylidene complexes, Cl2Ru{=C=C(H)tBut}(PCy3)(L) (L=PCy3 or N-heterocyclic carbenes) reveal themselves as a versatile catalyst for the atom transfer radical addition (ATRA) of polyhalogenated alkanes to olefins, such as methylmethacrylate, styrene and 1-octene. Furthermore, these systems are excellent catalysts for the nucleophilic addition of carboxylic acids to terminal alkynes and yielded exclusively alk-1-en-2-yl esters. These complexes can also be transformed to their cationic counterparts by treating the neutral complexes with AgBF4 and their catalytic potential in ATRA and vinylation reaction are investigated.
- Opstal, Tom,Verpoort, Francis
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p. 9259 - 9263
(2007/10/03)
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- The regioselective preparation of 1,3-diketones
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The regioselectivity of the acylation of Li enolates and silyl enol ethers is reported using acyl halides and acyl cyanides. We illustrate a simple method for the preparation of 1,3-diketones via the silyl enol ether in excellent yields, free from competing O-acylation and diacylation products.
- Wiles, Charlotte,Watts, Paul,Haswell, Stephen J.,Pombo-Villar, Esteban
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p. 2945 - 2948
(2007/10/03)
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- Ruthenium-catalyzed selective anti-Markovnikov trans addition of carboxylic acids and tail-to-tail dimerization of terminal alkynes
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Carboxylic acids react with terminal alkynes in the presence of a catalytic amount of RuClx(p-cymene)(triazol-5-ylidene) to selective generate Z-alk-1-en-1-yl esters. The anti-Markovnikov and trans addition on the terminal alkyne gives access t
- Melis, Karen,Samulkiewicz, Pawel,Rynkowski, Jacek,Verpoort, Francis
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p. 2713 - 2716
(2007/10/03)
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- Acid controlled alkyne dimerisation initiated by a Ru-carbene precursor
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The Grubb's catalyst Cl2(PR3)2Ru=CHPh (1) is an excellent precursor for the dimerisation of terminal alkynes. Thermal treatment and addition of two equivalents of phenylacetylene to complex 1 generates a new Ru-vinylidene (3). Complex 3 catalyses a selective product formation for trans-tail-to-tail enynes. Addition of acetic acid enhances the yield and the reaction rate dramatically and a reversed stereoselectivity for the formation of Z-isomers is obtained. The stereoselectivity can be easily tuned by addition of acetic acid. The influence of the acid on the reaction pathway has been revealed. A simple one-pot preparation of tail-totail enynes is established.
- Melis, Karen,De Vos, Dirk,Jacobs, Pierre,Verpoort, Francis
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p. 159 - 164
(2007/10/03)
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- Ruthenium indenylidene and vinylidene complexes bearing Schiff bases: Potential catalysts in enol-ester synthesis
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In an extension of our previous investigations on the ruthenium(II) Schiff-base chemistry, complexes 1, 2, 3a-b and 4a-b were synthesized and tested as catalyst for the nucleophilic addition of carboxylic acids to terminal alkynes. A careful choice of the catalytic system, substrate and carboxylic acid can provide alk-1-en-2-yl esters, alk-1-en-1-yl esters synthesis or enyne dimerization. In this way substituted isopropenol and α-methylenebenzyl formates, (geminal, geminal) dienol diesters were synthesized in one step by direct addition of formic acid or benzoic acid to terminal mono- and di-ynes.
- Opstal, Tom,Verpoort, Francis
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p. 935 - 941
(2007/10/03)
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- Ring-closing metathesis, Kharasch addition and enol ester synthesis catalysed by a novel class of ruthenium(II) complexes
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Ruthenium Schiff base complexes I-III mediated the Kharasch addition of carbon tetrachloride across olefins with high yields which markedly depended on the catalyst and the substrate used. In addition, ring-closing metathesis of some representative diolefins was carried out. The best catalytic system III is able to form tri- and tetrasubstituted double bond products. Finally, dependent of the catalytic system and the reaction conditions used, these systems can catalyse the stereoselective formation of enol esters or enynes in excellent yields.
- De Clercq, Bob,Verpoort, Francis
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p. 8959 - 8963
(2007/10/03)
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- Investigations into the regioselective deuteriation of enolates derived from silyl enol ethers and enolacetates
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Results are reported on the regioselective C-deuteriation of a series of enolates derived from the addition of MeLi to the related enolacetate and silyl enol ether and discussed in terms of the similarity between these methods; comments are made on the possible role of the additive, lithium tertbutoxide. Copyright
- Coumbarides, Gregory S.,Eames, Jason,Weerasooriya, Neluka
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p. 871 - 879
(2007/10/03)
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- Homolytic carbostannylation of alkenes and alkynes with tributylstannyl enolates
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matrix presented In the presence of AIBN, tributylstannyl enolates derived from aromatic ketones reacted with electron-deficient alkenes and a variety of alkynes to give the corresponding carbostannylated adducts. The reactions with methyl acrylate gave α-tributylstannylmethyl-γ-ketoesters, unlike the known Michael-type reaction of stannyl enolates forming δ-ketoesters. The carbostannylation of alkynes proceeded in an anti addition mode to afford β,γ-unsaturated ketones. The reactivity of stannyl enolates as radical transfer agents could be utilized for radical cyclization of 1,6-enynes.
- Miura, Katsukiyo,Saito, Hiroshi,Fujisawa, Naoki,Wang, Di,Nishikori, Hisashi,Hosomi, Akira
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p. 4055 - 4057
(2007/10/03)
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- Synthetic utility of stannyl enolates as radical alkylating agents
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(Equation presented) The radical-initiated β-ketoalkylation of haloalkanes with tributylstannyl enolates is described. Stannyl enolates derived from aromatic ketones are reactive toward the homolytic β-ketoalkylation of simple haloalkanes as well as those activated by an electron-withdrawing group. The reactivity of stannyl enolates as radical alkylating agents can be utilized for an efficient three-component coupling reaction among stannyl enolates, haloalkanes, and electron-deficient alkenes.
- Miura, Katsukiyo,Fujisawa, Naoki,Saito, Hiroshi,Wang, Di,Hosomi, Akira
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p. 2591 - 2594
(2007/10/03)
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- Enantioselective synthesis of hydroxy-substituted DBN-type amidines as potential chiral catalysts
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The synthesis and X-ray crystal structures of three enantiopure hydroxy- substituted amidines of the DBN-type are described. The key starting material, a 5-(phenylsulfonyl)pyrrolidin-2-one, was obtained by an oxazaborolidine-catalysed reductive desymmetrization of a meso-imide and was functionalized through N-acyliminium ion chemistry. The hydroxy groups were introduced by ozonolysis or reduction. Preliminary results on the use of the hydroxyamidines as chiral, bifunctional catalysts in selected Michael reactions are described.
- Ostendorf, Martin,Van Der Neut, Sandor,Rutjes, Floris P. J. T.,Hiemstra, Henk
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p. 105 - 113
(2007/10/03)
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- PALLADIUM CATALYZED INDIRECT ELECTROCHEMICAL ACETOXYLATION OF OLEFINS
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Olefins are acetoxylated to allylic and vinylic unsaturated esters by palladium (II) acetate catalyst in combination with controlled current anodic reoxidation and copper (II) acetate as an electron transfer agent.
- Hartstock, Frederick W.,Wayner, Danial, D. M.
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p. 8137 - 8140
(2007/10/02)
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