- Construction of a Protoberberine Alkaloid Skeleton via the Palladium-Catalyzed α-Arylation–Amide Formation Cascade
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In this work, we report the strategy of one-pot synthesis of protoberberine alkaloid derivatives via palladium-catalyzed cascade α-arylation and cyclization, which can afford the target molecules in moderate to excellent isolated yields using commercially available raw materials under solvent-free conditions. This protocol provides an efficient and convenient path to multisubstituted protoberberine derivatives. In addition, it can directly afford natural alkaloids.
- Li, Shaofeng,Nie, Hanyu,Duan, Mengyan,Wang, Wenfei,Zhu, Congjun,Song, Chuanjun
-
supporting information
p. 9631 - 9634
(2021/12/17)
-
- Tropylium-Promoted Hydroboration Reactions: Mechanistic Insights Via Experimental and Computational Studies
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Hydroboration reaction of alkynes is one of the most synthetically powerful tools to access organoboron compounds, versatile precursors for cross-coupling chemistry. This type of reaction has traditionally been mediated by transition-metal or main group catalysts. Herein, we report a novel method using tropylium salts, typically known as organic oxidants and Lewis acids, to promote the hydroboration reaction of alkynes. A broad range of vinylboranes can be easily accessed via this metal-free protocol. Similar hydroboration reactions of alkenes and epoxides can also be efficiently catalyzed by the same tropylium catalysts. Experimental studies and DFT calculations suggested that the reaction follows an uncommon mechanistic pathway, which is triggered by the hydride abstraction of pinacolborane with tropylium ion. This is followed by a series ofin situcounterion-activated substituent exchanges to generate boron intermediates that promote the hydroboration reaction.
- Mai, Binh Khanh,Nguyen, Thanh Vinh,Ton, Nhan N. H.
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p. 9117 - 9133
(2021/07/19)
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- Bench-Stable Manganese NHC Complexes for the Selective Reduction of Esters to Alcohols with Silanes
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Selective reduction of esters to alcohols was accomplished through Mn(I)-mediated hydrosilylation reaction. The manganese tricarbonyl complex [Mn(bis-NHC)(CO)3Br] resulted an active pre-catalyst for the reduction of a variety of esters using phenylsilane and the cheap and readily available polymethylhydrosiloxane. An in situ examination of the catalytic reaction using 55Mn NMR spectroscopy allowed us to detect the formation of Mn(I) intermediate active species. (Figure presented.).
- Sousa, Sara C. A.,Realista, Sara,Royo, Beatriz
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p. 2437 - 2443
(2020/04/30)
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- Iron-Catalyzed β-Alkylation of Alcohols
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β-Branched alkylated alcohols have been prepared in good yields using a double-hydrogen autotransfer strategy in the presence of our diaminocyclopentadienone iron tricarbonyl complex Fe1. The alkylation of some 2-arylethanol derivatives was successfully addressed with benzylic alcohols and methanol as alkylating reagents under mild conditions. Deuterium labeling experiments suggested that both alcohols (2-arylethanol and either methanol or benzyl alcohol) served as hydrogen donors in this cascade process.
- Bettoni, Leó,Gaillard, Sylvain,Renaud, Jean-Luc
-
supporting information
p. 8404 - 8408
(2019/10/16)
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- Amino-polystyrene supported hexaethylene glycol-bridged ionic liquid as an efficient heterogeneous catalyst for water-mediated nucleophilic hydroxylation
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We report a simple and eco-friendly method for producing an amino-polystyrene supported hexaethylene glycol-bridged ionic liquid (APS-HEGBIL) based on the copolymerization of amino-styrene with 1-vinyl imidazolium ionic liquid bearing hexaethylene glycol moieties, and its characterization by several analytical techniques. The resulting APS-HEGBIL catalyst was found to be remarkably efficient at catalyzing the selective nucleophilic hydroxylation of alkyl halides to produce the corresponding alcohols in water, which acted as a solvent and a nucleophilic hydroxide source. The catalyst was easily recycled and maintained its catalytic activity and stability after ten cycles with excellent yields. The main attributes of the catalyst were that it significantly enhanced the nucleophilicity of water during reactions and promoted the rapid conversions of polar and base-sensitive alkyl halide reactants to alcohols in excellent yields. The combination of ionic liquids and polymeric materials afforded quasi-homogeneous catalysts that were recycled by simple filtration and provided environmentally benign means for conducted catalytic procedures.
- Reddy, Mudumala Veeranarayana,Kang, Seok Min,Yoo, Suah,Woo, Sang Sik,Kim, Dong Wook
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p. 9435 - 9442
(2019/04/01)
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- Reliably Regioselective Dialkyl Ether Cleavage with Mixed Boron Trihalides
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A protocol for the regioselective cleavage of unsymmetrical alkyl ethers to generate alkyl alcohol and alkyl bromide products is described. A mixture of trihaloboranes triggers this conversion and exhibits improved reactivity profiles (regioselectivity and yield) compared with BBr3 alone. Additionally, this procedure allows the efficient synthesis of (B-Cl) dialkyl boronate esters. There are limited methods to generate acyclic dialkoxyboryl chlorides, and these intermediates constitute important synthons in main-group chemistry.
- Atienza, Bren Jordan P.,Truong, Nam,Williams, Florence J.
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supporting information
p. 6332 - 6335
(2018/10/09)
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- Highly sulphated cellulose: a versatile, reusable and selective desilylating agent for deprotection of alcoholic TBDMS ethers
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A mild, efficient and rapid protocol was developed for the deprotection of alcoholic TBDMS ethers using a recyclable, eco-friendly highly sulphated cellulose sulphate acid catalyst in methanol. This acid catalyst selectively cleaves alcoholic TBDMS ethers in bis-TBDMS ethers containing both alcoholic and phenolic TBDMS ether moieties.
- Dachavaram, Soma Shekar,Penthala, Narsimha R.,Calahan, Julie L.,Munson, Eric J.,Crooks, Peter A.
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p. 6057 - 6062
(2018/09/06)
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- TiO2-Supported Re as a General and Chemoselective Heterogeneous Catalyst for Hydrogenation of Carboxylic Acids to Alcohols
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TiO2-supported Re, Re/TiO2, was found to promote selective hydrogenation of carboxylic acids having aromatic and aliphatic moieties to the corresponding alcohols. Re/TiO2showed superior results compared to other transition-metal-loaded TiO2and supported Re catalysts for selective hydrogenation of 3-phenylpropionic acid. 3-phenylpropanol was produced in 97 % yield under mild conditions (5 MPa H2at 140 °C). Contrary to typical heterogeneous catalysts, Re/TiO2does not lead to the formation of dearomatized byproducts. The catalyst is recyclable and shows a wide substrate scope in the synthesis of alcohols (22 examples; up to 97 % isolated yield).
- Toyao, Takashi,Siddiki, S. M. A. Hakim,Touchy, Abeda S.,Onodera, Wataru,Kon, Kenichi,Morita, Yoshitsugu,Kamachi, Takashi,Yoshizawa, Kazunari,Shimizu, Ken-Ichi
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p. 1001 - 1006
(2017/02/05)
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- Regioselective hydrosilylation of epoxides catalysed by nickel(II) hydrido complexes
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Bench-stable nickel fluoride complexes bearing NNN pincer ligands have been employed as precursors for the regioselective hydrosilylation of epoxides at room temperature. A nickel hydride assisted epoxide opening is followed by the cleavage of the newly formed nickel oxygen bond by σ-bond metathesis with a silane.
- Wenz, Jan,Wadepohl, Hubert,Gade, Lutz H.
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supporting information
p. 4308 - 4311
(2017/04/21)
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- Rhenium-Loaded TiO2: A Highly Versatile and Chemoselective Catalyst for the Hydrogenation of Carboxylic Acid Derivatives and the N-Methylation of Amines Using H2 and CO2
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Herein, we report a heterogeneous TiO2-supported Re catalyst (Re/TiO2) that promotes various selective hydrogenation reactions, which includes the hydrogenation of esters to alcohols, the hydrogenation of amides to amines, and the N-methylation of amines, by using H2 and CO2. Initially, Re/TiO2 was evaluated in the context of the selective hydrogenation of 3-phenylpropionic acid methyl ester to afford 3-phenylpropanol (pH2 =5 MPa, =5 MPa, T=180 °C), which revealed a superior performance over other catalysts that we tested in this study. In contrast to other typical heterogeneous catalysts, hydrogenation reactions with Re/TiO2 did not produce dearomatized byproducts. DFT studies suggested that the high selectivity for the formation of alcohols in favor of the hydrogenation of aromatic rings is ascribed to the higher affinity of Re towards the COOCH3 group than to the benzene ring. Moreover, Re/TiO2 showed a wide substrate scope for the hydrogenation reaction (19 examples). Subsequently, this Re/TiO2 catalyst was applied to the hydrogenation of amides, the N-methylation of amines, and the N-alkylation of amines with carboxylic acids or esters.
- Toyao, Takashi,Siddiki,Morita, Yoshitsugu,Kamachi, Takashi,Touchy, Abeda S.,Onodera, Wataru,Kon, Kenichi,Furukawa, Shinya,Ariga, Hiroko,Asakura, Kiyotaka,Yoshizawa, Kazunari,Shimizu, Ken-Ichi
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supporting information
p. 14848 - 14859
(2017/10/27)
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- FUNCTIONALISED AND SUBSTITUTED INDOLES AS ANTI-CANCER AGENTS
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The present invention relates to anti-tropomyosin compounds, processes for their preparation, and methods for treating or preventing a disease or disorder, such as a proliferative disease (preferably cancer), using compounds of the invention.
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Page/Page column 58; 59
(2016/02/05)
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- Synthesis of 5,6-Dihydropyrazolo[5,1-a]isoquinoline and Ethyl (Z)-3-Acetoxy-3-tosylpent-4-enoate through Tertiary-Amine-Catalyzed [3+2] Annulation
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The 1,4-diazabicyclo[2.2.2]octane (DABCO) catalyzed divergent [3+2] annulation of C,N-cyclic azomethine imines with δ-acetoxyallenoates was developed; 5,6-dihydropyrazolo[5,1-a]isoquinolines and ethyl (Z)-3-acetoxy-3-tosylpent-4-enoates were afforded in moderate to good yields in a one-pot manner under mild conditions. This annulation reaction provides a highly efficient method to construct dinitrogen-fused heterocycles and ethyl (Z)-3-acetoxy-3-tosylpent-4-enoates at the same time.
- Lei, Yu,Xing, Jiao-Jiao,Xu, Qin,Shi, Min
-
supporting information
p. 3486 - 3490
(2016/07/28)
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- Direct Ruthenium-Catalyzed Hydrogenation of Carboxylic Acids to Alcohols
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The "green" reduction of carboxylic acids to alcohols is a challenging task in organic chemistry. Herein, we describe a general protocol for generation of alcohols by catalytic hydrogenation of carboxylic acids. Key to success is the use of a combination of Ru(acac)3, triphos and Lewis acids. The novel method showed broad substrate tolerance and a variety of aliphatic carboxylic acids including biomass-derived compounds can be smoothly reduced.
- Cui, Xinjiang,Li, Yuehui,Topf, Christoph,Junge, Kathrin,Beller, Matthias
-
supporting information
p. 10596 - 10599
(2015/09/02)
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- Nucleophilic Hydroxylation in Water Media Promoted by a Hexa-Ethylene Glycol-Bridged Dicationic Ionic Liquid
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Hexaethylene glycol bis(3-hexaethylene glycol imidazolium) dimesylate ionic liquid (hexaEG-DHIM) was designed and prepared as a highly efficient promoter for the nucleophilic hydroxylation of alkyl halides to the corresponding alcohol products in neat water media. It was observed that hexaEG-DHIM promoter enhanced the nucleophilicity of water significantly in the reaction. In addition, the hexaEG-DHIM could be reused several times without loss of activity. Moreover, the hydroxylation reactions of base-sensitive and/or polar alkyl halide substrates proceeded highly chemoselectively in excellent yields.
- Jadhav, Vinod H.,Kim, Jin Gwan,Jeong, Hyeon Jin,Kim, Dong Wook
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p. 7275 - 7280
(2015/07/28)
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- A General, Practical Triethylborane-Catalyzed Reduction of Carbonyl Functions to Alcohols
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A combination of the abundant and low-cost triethylborane and sodium alkoxide generates a highly efficient catalyst for reduction of esters, as well as ketones and aldehydes, to alcohols using an inexpensive hydrosilane under mild conditions. The catalyst system exhibits excellent chemoselectivity and a high level of functional group tolerance. Mechanistic studies revealed a resting state of sodium triethylalkoxylborate that is the product of the reaction of BEt3 with sodium alkoxide. This borate species reacts with hydrosilane to form NaBEt3H, which rapidly reduces esters.
- Peng, Dongjie,Zhang, Mintao,Huang, Zheng
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supporting information
p. 14737 - 14741
(2015/10/19)
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- Solvent-free reduction of carboxylic acids to alcohols with NaBH4 promoted by 2,4,6-trichloro-1,3,5-triazine and PPh3 in the presence of K2CO3
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A simple, rapid, and eco-friendly method for NaBH4 reduction of carboxylic acids to alcohols under solvent-free conditions was developed using a combination of 2,4,6-trichloro-1,3,5-triazine (TCT) with a catalytic amount of triphenylphosphine as an acid activator. With the 1 : 0.2 : 1.5 : 2 mole ratio of TCT : PPh3 : K2CO3 : NaBH4, carboxylic acids including aromatic acids, aliphatic acids, and N-protected α-amino acids (Fmoc, Z) could readily undergo reduction to give the corresponding alcohols in good to excellent yields within 10 min.
- Jaita, Subin,Kaewkum, Pantitra,Duangkamol, Chuthamat,Phakhodee, Wong,Pattarawarapan, Mookda
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p. 46947 - 46950
(2014/12/10)
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- Achiral pyrazinone-based inhibitors of the hepatitis C virus NS3 protease and drug-resistant variants with elongated substituents directed toward the S2 pocket
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Herein we describe the design, synthesis, inhibitory potency, and pharmacokinetic properties of a novel class of achiral peptidomimetic HCV NS3 protease inhibitors. The compounds are based on a dipeptidomimetic pyrazinone glycine P3P2 building block in combination with an aromatic acyl sulfonamide in the P1P1′ position. Structure-activity relationship data and molecular modeling support occupancy of the S2 pocket from elongated R6 substituents on the 2(1H)-pyrazinone core and several inhibitors with improved inhibitory potency down to Ki = 0.11 μM were identified. A major goal with the design was to produce inhibitors structurally dissimilar to the di- and tripeptide-based HCV protease inhibitors in advanced stages of development for which cross-resistance might be an issue. Therefore, the retained and improved inhibitory potency against the drug-resistant variants A156T, D168V, and R155K further strengthen the potential of this class of inhibitors. A number of the inhibitors were tested in in vitro preclinical profiling assays to evaluate their apparent pharmacokinetic properties. The various R6 substituents were found to have a major influence on solubility, metabolic stability, and cell permeability.
- Gising, Johan,Belfrage, Anna Karin,Alogheli, Hiba,Ehrenberg, Angelica,?kerblom, Eva,Svensson, Richard,Artursson, Per,Karlén, Anders,Danielson, U. Helena,Larhed, Mats,Sandstr?m, Anja
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p. 1790 - 1801
(2014/04/03)
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- Fe-promoted cross coupling of homobenzylic methyl ethers with Grignard reagents via sp3 C-O bond cleavage
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The first iron-catalyzed formal cross coupling of homobenzylic methyl ethers with alkyl Grignard reagents is realized. The reaction is proposed to proceed through a sequence of dehydroalkoxylation to form the vinyl-intermediate, followed by Fe-catalyzed selective carbometalation to form a benzylic Grignard reagent.
- Luo, Shuang,Yu, Da-Gang,Zhu, Ru-Yi,Wang, Xin,Wang, Lei,Shi, Zhang-Jie
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supporting information
p. 7794 - 7796
(2013/09/02)
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- Selective switchable iron-catalyzed hydrosilylation of carboxylic acids
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Selective reduction of carboxylic acids either to aldehydes or alcohols is achieved using a one pot procedure based on iron-catalyzed hydrosilylations. Using phenylsilane and (COD)Fe(CO)3 catalyst under UV-irradiation at rt, alcohols were obtained specifically in good yields, whereas aldehydes were selectively obtained using TMDS and (t-PBO)Fe(CO)3 catalyst under thermal activation.
- Misal Castro, Luis C.,Li, Haoquan,Sortais, Jean-Baptiste,Darcel, Christophe
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supporting information
p. 10514 - 10516,3
(2020/09/02)
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- Regioselective synthesis of substituted naphthalenes and phenanthrenes by FeCl3-promoted annulation of aryl and naphthyl acetaldehydes with alkynes
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The FeCl3-promoted annulation reaction of aryl acetaldehydes with alkynes has been established, which provides a new and versatile straightforward procedure for the regioselective synthesis of mono-, di-, and polysubstituted naphthalenes under mild conditions. Interestingly, the present catalytic system not only differentiates between internal and terminal alkynes but also shows unprecedented complete Me3SiOH elimination selectivity for silyl alkyne substrates. Furthermore, the synthesis of a series of substituted phenanthrenes via reactions of nathphyl acetaldehydes with internal alkynes is also achieved for the first time in good yields with excellent regioselectivity.
- Bu, Xiuli,Hong, Longcheng,Liu, Ruiting,Hong, Jianquan,Zhang, Zhengxing,Zhou, Xigeng
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experimental part
p. 7960 - 7965
(2012/09/21)
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- Iron-catalyzed hydrosilylation of esters
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The first hydrosilylation of esters catalyzed by a well defined iron complex has been developed. Esters are converted to the corresponding alcohols at 100 °C, under solvent-free conditions and visible light activation. Copyright
- Bezier, David,Venkanna, Gopaladasu T.,Castro, Luis C. Misal,Zheng, Jianxia,Roisnel, Thierry,Sortais, Jean-Baptiste,Darcel, Christophe
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supporting information; experimental part
p. 1879 - 1884
(2012/09/22)
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- InBr3-catalyzed deoxygenation of carboxylic acids with a hydrosilane: Reductive conversion of aliphatic or aromatic carboxylic acids to primary alcohols or diphenylmethanes
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A simple and practical procedure for the direct reduction of aliphatic carboxylic acids with a variety of functional groups to a primary alcohol using the mild reducing reagent tetramethyldisiloxane (TMDS), in the presence of a catalytic amount of InBr3 has been developed. This simple reducing system, when used together with a hydrosilane, allows the preparation of the diphenylmethane derivative directly from an aromatic carboxylic acid and an aromatic compound. Copyright
- Sakai, Norio,Kawana, Keita,Ikeda, Reiko,Nakaike, Yumi,Konakahara, Takeo
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experimental part
p. 3178 - 3183
(2011/06/28)
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- Copper-catalyzed enantioselective additions to oxocarbenium ions: Alkynylation of isochroman acetals
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We have developed an enantioselective, copper(I)-catalyzed addition of terminal alkynes to racemic isochroman acetals. This method is one of the first transition-metal-catalyzed approaches to enantioselective additions to prochiral oxocarbenium ions. In this reaction, TMSOTf is used to form the oxocarbenium ion in situ under conditions compatible with simultaneous formation of the chiral copper acetylide. By using a bis(oxazoline) ligand, good yields and enantioselectivities are observed for a variety of enantioenriched 1-alkynyl isochromans.
- Maity, Prantik,Srinivas, Harathi D.,Watson, Mary P.
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supporting information; experimental part
p. 17142 - 17145
(2011/12/13)
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- Tetrabutylammonium tetra(tert-butyl alcohol)-coordinated fluoride as a facile fluoride source
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(Figure Presented) F- on: The title compound TBAF(tBuOH) 4 can act as a highly effective fluoride source for nucleophilic fluorination thanks to its favorable properties, such as a stable structure (in which the fluoride ion is surrounded by four bulky nonpolar protic alcohol molecules), a dehydrated state, low hygroscopicity, good solubility in organic solvents, good nucleophilicity, and low basicity.
- Kim, Dong Wook,Jeong, Hwan-Jeong,Lim, Seok Tae,Sohn, Myung-Hee
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supporting information; body text
p. 8404 - 8406
(2009/05/15)
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- Unexpected selectivity in sodium borohydride reductions of α-substituted esters: Experimental and theoretical studies
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The propensity of sodium borohydride to reduce the carbonyl group in eleven α-substituted and two aromatic esters has been investigated by experiments and at the B3LYP/6-31++G(d,p)//HF/6-31G(d,p) level of theory. The chemoselectivities in nine of these reductions have been examined by experiments. Experimental results agree well with the calculated order of activation energies for hydride transfer to the ester carbonyl group. Methyl α-bromoacetate reduces faster than methyl α-fluoroacetate. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Li, Liang-Chun,Jiang, Ju-Xing,Ren, Jie,Ren, Yi,Pittman Jr., Charles U.,Zhu, Hua-Jie
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p. 1981 - 1990
(2007/10/03)
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- Fluorous triphase and other multiphase systems
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A method of reacting a first non-fluorous compound to produce a second non-fluorous compound includes the steps of: contacting a first non-fluorous phase including the first non-fluorous compound with a first fluorous phase at a first phase interface, the first non-fluorous compound distributing between the first fluorous phase and the first non-fluorous phase; contacting the first fluorous phase with a second non-fluorous phase at a second phase interface; and including at least a third non-fluorous compound in the second non-fluorous phase that reacts with the first non-fluorous compound to produce the second non-fluorous compound, the second non-fluorous compound having a distribution coefficient less than the first non-fluorous compound. For example, the first non-fluorous compound can be dibromine or diiodine, and the second non-fluorous compound can be an alkene.
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- Efficient and simple NaBH4 reduction of esters at cationic micellar surface
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(Chemical Equation Presented) A simple, efficacious, and biocompatible methodology for reducing esters with sodium borohydride at an aqueous cationic micellar surface under ambient conditions has been developed. The present method holds promise for future use in selective functional group reduction and stereocontrolled alcohol synthesis.
- Das, Debapratim,Roy, Sangita,Das, Prasanta Kumar
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p. 4133 - 4136
(2007/10/03)
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- Intramolecular C-N bond formation reactions catalyzed by ruthenium porphyrins: Amidation of sulfamate esters and aziridination of unsaturated sulfonamides
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Ruthenium porphyrins [Ru(F20-TPP)(CO)] (F20-TPP = 5,10,15,20-tetrakis(pentafluorophenyl)porphyrinato dianion) and [Ru(Por*)(CO)] (Por* = 5,10,15,20-tetrakis[(1S,4R,5R,8S)-1,2,3,4,5,6,7,8-octahydro-1,4:5, 8-dimethanoanthracen-9-yl]porphyrinato dianion) catalyzed intramolecular amidation of sulfamate esters p-X-C6H4(CH 2)2OSO2NH2 (X = Cl, Me, MeO), XC6H4(CH2)3OSO2NH 2 (X = p-F, p-MeO, m-MeO), and Ar(CH2)2OSO 2NH2 (Ar = naphthalen-1-yl, naphthalen-2-yl) with PhI(OAc)2 to afford the corresponding cyclic sulfamidates in up to 89% yield with up to 100% substrate conversion; up to 88% ee was attained in the asymmetric intramolecular amidation catalyzed by [Ru(Por*)(CO)]. Reaction of [Ru(F20-TPP)(CO)] with PhI=NSO2OCH 2CCl3 (prepared by treating the sulfamate ester Cl 3CCH2OSO2NH2 with PhI(OAc) 2) afforded a bis(imido)ruthenium(VI) porphyrin, [Ru VI(F20-TPP)(NSO2OCH2CCl 3)2], in 60% yield. A mechanism involving reactive imido ruthenium porphyrin intermediate was proposed for the ruthenium porphyrin-catalyzed intramolecular amidation of sulfamate esters. Complex [Ru(F20-TPP)(CO)] is an active catalyst for intramolecular aziridination of unsaturated sulfonamides with PhI(OAc)2, producing corresponding bicyclic aziridines in up to 87% yield with up to 100% substrate conversion and high turnover (up to 2014).
- Liang, Jiang-Lin,Yuan, Shi-Xue,Huang, Jie-Sheng,Che, Chi-Ming
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p. 3610 - 3619
(2007/10/03)
-
- Fluorous triphase and other multiphase systems
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A method of reacting a first compound to produce a second compound includes the step of contacting a first non-fluorous phase including the first compound with a first fluorous phase at a first phase interface. The first compound distributes between the first fluorous phase and the first non-fluorous phase. The method further includes the steps of contacting the first fluorous phase with a second non-fluorous phase at a second phase interface and including at least a third compound in the second non-fluorous phase that reacts with the first compound to produce the second compound. The second compound has a distribution coefficient less than the first compound. This method can, for example be used to separate the second compound from unreacted first compound wherein, for example, the first compound is of a fluorous nature and distributes more readily into (or transports more quickly through) the fluorous phase than does the second compound. In general, the fluorous phase serves as a barrier to prevent the two non-fluorous phases from mixing, but molecules that can migrate through the fluorous phase can pass from one side to the other.
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- Fluorous triphase and other multiphase systems
-
A method of reacting a first non-fluorous compound to produce a second non-fluorous compound includes the steps of: contacting a first non-fluorous phase including the first non-fluorous compound with a first fluorous phase at a first phase interface, the first non-fluorous compound distributing between the first fluorous phase and the first non-fluorous phase; contacting the first fluorous phase with a second non-fluorous phase at a second phase interface; and including at least a third non-fluorous compound in the second non-fluorous phase that reacts with the first non-fluorous compound to produce the second non-fluorous compound, the second non-fluorous compound having a distribution coefficient less than the first non-fluorous compound. For example, the first non-fluorous compound can be dibromine or diiodine. and the second non-fluorous compound can be an alkene.
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- Smiles-type free radical rearrangement of aromatic sulfonates and sulfonamides: Syntheses of arylethanols and arylethylamines
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Smiles-type free radical rearrangements of arenesulfonates and arenesulfonamides are exploited for synthetic purposes. 4-Substituted benzenesulfonates cause Smiles-type rearrangement only when substituted by an electron withdrawing group. Therefore, ipso-sttack by an alkyl radical on arenesulfonates takes place in an electrophilic manner. Arenesulfonamides rearrange only when the amide nitrogen is substituted by an alkoxycarbonyl group, due to the electron withdrawing nature of this group. Sulfonates and the N-ethoxycarbonylsulfonamide derivatives of naphthalene, quinoline, and thiophene cause more rearrangement and show synthetic utility. Aromatic amino acid analogues were synthesized by Smiles-type rearrangement with moderate yields. The radical Smiles-type rearrangement of sulfonate and sulfonamide derivatives can be a useful synthetic route when we understand the electronic character of these reactions.
- Tada, Masaru,Shijima, Hiroyasu,Nakamura, Masaharu
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p. 2499 - 2505
(2007/10/03)
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- Selective formylation of alcohols in the presence of phenols with chloral
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Primary and secondary alcohols were formylated selectively in the presence of phenols by stirring with chloral in acetone over anhydrous K2CO3 at ambient temperatures in high yields.
- Ram, Ram N,Meher, Nabin Kumar
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p. 2997 - 3001
(2007/10/03)
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- A new method for the synthesis of α-thio aldehydes and alcohols from aldehydes with one-carbon elongation
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A two-step and high-yield method for the synthesis of α-thio aldehydes from aldehydes with one-carbon elongation is realized by using chloromethyl phenyl sulfoxide as a one-carbon homologating agent. The α-thio aldehydes are easily converted to desulfurized alcohols with Bu3SnH and AIBN in refluxing benzene in good yield. (C) 2000 Elsevier Science Ltd.
- Satoh, Tsuyoshi,Kubota, Ko-Ichi
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p. 2121 - 2124
(2007/10/03)
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- The scope of catalytic asymmetric hydroboration/oxidation with rhodium complexes of 1,1'-(2-diarylphosphino-1-naphthyl)isoquinolines
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Preformed cationic Rh complexes of the title ligands are effective for the asymmetric hydroboration/oxidation of vinylarenes at ambient temperature. These vinylarenes may carry E- or Z-β substituents but not a substituents. Enantiomer excesses of up to 97% can be obtained in the most favourable cases. The enantioselectivity is moderately sensitive to the structure of the ligand: the difurylphosphino ligand gave superior results for electron-poor styrenes and the diphenylphosphino ligand the best results for electron-rich reactants. Mechanistic aspects are discussed.
- Doucet, Henri,Fernandez, Elena,Layzell, Timothy P.,Brown, John M.
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p. 1320 - 1330
(2007/10/03)
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- Design and Synthesis of Naphthalenic Derivatives as Potential Inhibitors of Hydroxyindole-O-methyltransferase
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Hydroxyindole-O-methyltransferase is an enzyme that catalyses the last step of melatonin biosynthesis. The objective of this work was to design and synthesize potential inhibitors of hydroxyindole-O-methyltransferase. Applying bioisosteric principles to the indolic nucleus, we considered the synthesis of naphthalenic derivatives and varied the nature of substituents at position 7 and the amide group. We also replaced the ethylene moiety at position 1 by its lower and higher homologues, and synthesized C4 retroamides. Of the compounds synthesized, N-[2-(7-naphth-1-yl)]phenylacetamide was the best inhibitor of hydroxyindole-O-methyltransferase (77 percent inhibition at a concentration of 10-4 M). Moreover, most of naphthols behaved as enzyme substrates. The ethyl side chain at position 1 was an essential element for optimal biological activity.
- Picard, I. le,Depreux, P.,Lesieur, I.,Delagrange, P.,Bennejean, C.,Renard, P.,Voisin, P.
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p. 183 - 188
(2007/10/03)
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- Design of radical clocks to probe the reactivity of the intermediated in arylmethyl ester photochemistry
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The photochemistry in methanol of the esters 1-6 was examined. These reactions normally proceed through radical pairs that result from homolytic cleavage of the carbon-oxygen bond in the excited singlet state. Each of the esters was designed to probe the intervention and reactivity of the substituted arylmethyl radical by incorporating a potential radical clock at the carbon of the reactive bond. For esters 1-5, the products isolated indicated that the radical clock was not reactive enough to compete with the very rapid alternate processes of the radical pair, namely, electron transfer to form the corresponding ion pair and decarboxylation of the phenylacyloxy radical (k = 4.6×109 s-1). Ester 6, which incorporates the extremely rapid fluorenylcyclopropylcarbinyl clock, showed very unusual reactivity. On thermal solvolysis in methanol, 6 rearranged quantitatively to the ester 20. No methyl ethers were detected. In contrast, photolysis of 6 in benzene resulted in an alternate rearrangement to the cyclobutyl ester, 22, resulting from the aryl version of the cyclopropyl-π-methane photochemical rearrangement. No ester cleavage occurred on excitation. A rationale for the latter conversion was based on stereoelectronic arguments provided by a crystal structure of 6.
- Nevill,Pincock
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p. 232 - 247
(2007/10/03)
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- Synthesis of substituted chrysenes and phenanthrenes
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3-Methylchrysene (9a), 2, 3, 9-trimethylchrysene (9b), 2, 6-dimethylphenanthrene (16a) and 1-isopropyl-4,6-dimethylphenanthrene (16b) have been synthesised in the following steps. β-(1-Naphthyl)ethyl bromide (6a), β-(6,7-dimethyl-1-naphthyl)ethyl bromide (6b), β-(3-methylphenyl)ethyl bromide (13a) and β-(2-isopropyl-5-methylphenyl)ethyl bromide (13b) are separately condensed with potassium salt of 1-carbethoxy-4-methylcyclohexane-2-one (1) to give respectively 7a, 7b, 14a and 14b. PPA cyclisation of 7a and 7b affords 8a and 8b while 14a affords 15a and 14b gives a mixture of 15b and 15c. Aromatisation of 8a and 8b leads to 9a and 9b and that of 15a gives 16a while 15b and 15c both produce 16b. The structures assigned are consistent with their spectral data.
- Mitra, Ashutosh,Ghoshe, Swati
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p. 785 - 789
(2007/10/03)
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- Generation of Radical-cations from Naphthalene and Some Derivatives, both by Photoionization and Reaction with SO4-.: Formation and Reactions Studied by Laser Flash Photolysis
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Radical-cations from naphthalene and some derivatives have been generated in aqueous acetonitrile both by direct photolysis (with λ 248 nm light via biphotonic ionization) and via reaction with SO4-..The radical-cation reacts rapidly with the parent substrate (k ca. 1E8 dm3 mol-1 s-1) and with nucleophiles (e. g. with N3- k = 4.2*1E9 dm3 mol-1 s-1 or with water, k 4*1E4 s-1 ).The radical-cation from 1-naphthylethanoic acid undergoes rapid decarboxylation (k 5*1E5 s-1).The radical cations from 4-methyl- and 4-methoxy-phenylethanoic acid also rapidly decarboxylate to yield the corresponding benzyl radicals.
- Steenken, Steen,Warren, Cathryn J.,Gilbert, Bruce C.
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p. 335 - 342
(2007/10/02)
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- A Practical Large-scale Synthesis of (1-Naphthyl)acetylene
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1-Ethynylnaphthalene has been synthesized on a large scale with high overall yields starting from 1-bromonaphthalene.
- Hanekamp, Jaap C.,Klusener, Peter A. A.
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p. 2677 - 2682
(2007/10/02)
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- INTER- AND INTRA-MOLECULAR PHOTOCYCLOADDITION OF ENOL ETHERS TO NAPHTHALENE
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The isomeric non-conjugated naphthyl enol ether bichromophores (6) and (7) display markedly different photoreactivities.The former undergoes ? + 2?> cycloaddition from the S1 state whereas the latter is relatively photostable.The two cyano derivatives (4) and (5) both yield intramolecular cycloadducts but the orientation of the addition is the opposite of that predicted from the reported intermolecular cyanonaphthalene-enol ether photoreactions. 2,3-Dihydrofuran undergoes specific "head to head" endo photoaddition to naphthalene but in contrast the major adducts from 2,3-dihydrofuran and this arene have "head to head" exo and "head to tail" endo structures.The adduct (18) undergoes a facile 1,3-shift to yield the (4? + 2?) endo adduct (19).The reactivities of the bichromophores and the regiochemistries of the additions are considered in relation to the relative charge densities at the 1- and 2-positions of the S1 arene.
- Gilbert, Andrew,Heath, Peter,Kashoulis-Koupparis, Annoula,Ellis-Davies, Graham C. R.,Firth, Susan M.
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- Homolytic versus heterolytic cleavage for the photochemistry of 1-naphthylmethyl derivatives
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The photochemical cleavage of the 1-naphthylmethyl derivatives, 1-7, has been examined in methanol solvent under both direct and sensitized conditions.The competition between homolytic and heterolytic cleavage as a function of multiplicity and leaving group has been studied in detail.Only substrates 1, 2, 3, and 7 react on sensitization with xanthone but evidence is presented that the resulting reactivity of 1, 2, and 3 may not be triplet energy transfer but rather exciplex formation.A semi-quantitative scale for photofugacities of the leaving groups from the excited singlet states has been established.
- Arnold, B.,Donald, L.,Jurgens, A.,Pincock, J. A.
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p. 3140 - 3146
(2007/10/02)
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- THE PHOTOPHYSICS OF SOME INTRAMOLECULAR TERNARY COMPLEXES FORMED BETWEEN ARYL AND AMINO GROUPS
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The fluorescence properties of (3)-(6) in solvents of varying polarity have been examined and the conclusion reached that in non-polar solvents they exhibit fluorescence (low quantum yield) from an intramolecular ternary complex.In polar solvents very little fluorescence is observable.Although each compound exhibits extensive intramolecular fluorescence quenching, the quantum yield of localised triplet naphthalene in non-polar solvents remains relatively high indicating that intersystem crossing occurs in the non-relaxed exciplex.
- Beecroft, Richard A.,Davidson, Stephen R.,Goodwin, Dean
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p. 3853 - 3866
(2007/10/02)
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- Photochemistry of Naphthylmethyl Halides. Direct and Sensitized Paths to Homolytic and Heterolytic Carbon-Halogen Bond Cleavage
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Photolysis of the 1-(halomethyl)naphthalenes (X=Cl, Br, I) in methanol and in cyclohexane solution was investigated.Direct and sensitized irradiation leads to carbon-halogen bond cleavage.In methanol solution direct irradiation leads to products of carbon-halogen bond heterolysis, i.e. (methoxymethyl)naphthalene, as well as products derived from bond homolysis.In cyclohexane only homolysis products are observed.The mechanism of the photoreactions was probed by laser spectroscopy, sensitization, and quenching techniques.The results indicate that bond cleavage occurs from excited singlet states but not from the lowest triplet state.Also, an exciplex between sensitizers and the (halomethyl)naphthalene also undergoes carbon-halogen bond cleavage.
- Slocum, Gregory H.,Schuster, Gary B.
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p. 2177 - 2185
(2007/10/02)
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- CHEMISTRY AND KINETICS OF ARYL CARBENES IN METHANOL AT LOW TEMPERATURES.
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The chemistry and kinetics of six aryl carbenes in polycrystalline methanol are reported. The kinetics were monitored by triplet ESR spectroscopy. Isotope effects were used heavily to probe reaction mechanisms. Several analogues to solution chemistry and kinetics were found. It is concluded that the singlet-triplet energy separation decreases as DBS greater than DPC greater than DBT greater than NC greater than Fl greater than DMA.
- Wright,Platz
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p. 4175 - 4180
(2007/10/02)
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