- Copper-catalyzed (4+1) and (3+2) cyclizations of iodonium ylides with alkynes
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The copper(ii)-catalyzed (4+1) cyclizations and copper(i)-catalyzed (3+2) cycloadditions of iodonium ylides and alkynes were successfully developed by employing efficient and safe iodonium ylides instead of traditional diazo compounds. Highly functionaliz
- Liang, Hao,He, Xiaobo,Zhang, Yaqi,Chen, Bin,Ouyang, Jia-Sheng,Li, Yongsu,Pan, Bendu,Subba Reddy, Chitreddy V.,Chan, Wesley Ting Kwok,Qiu, Liqin
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supporting information
p. 11429 - 11432
(2020/10/12)
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- Synthesis of indole-fused heteroacenes by cascade cyclisation involving rhodium(ii)-catalysed intramolecular C-H amination
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Heteroacenes are potentially important materials for organic electronics and their syntheses are of topical interest. Herein we report the development of a catalytic, redox-neutral reaction for the synthesis of the 5,10-dihydroindolo[3,2-b]indole class of
- Matsuda, Takanori,Ito, Hirotaka
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supporting information
p. 6703 - 6707
(2018/09/29)
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- A concise total synthesis of biologically active frutinones via tributylphosphine-catalyzed tandem acyl transfer-cyclization
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A concise and step-economical total synthesis of biologically active frutinones has been achieved. Tributylphosphine (PBu3) efficiently induced the tandem acyl transfer-cyclization of carbonates 5 to afford 3-methoxycarbonylflavone derivatives 4 in excellent yields. Finally, concomitant deprotection and lactonization under acidic conditions furnished the desired frutinones A (1a), B (1b), and the proposed structure of frutinone C (1c).
- Yoshida, Masahito,Saito, Koya,Fujino, Yuta,Doi, Takayuki
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p. 3452 - 3458
(2014/05/06)
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- Exploring the potential of diarylacetylenediols as hydrogen bonding catalysts
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In the course of a search for new classes of hydrogen bonding catalysts, we have examined diarylacetylenediols as potential catalysts for the Diels-Alder reaction. General and efficient methods have been developed for the preparation of these diols. Their structures were systematically modified, and increased activity was observed for those possessing an electron-withdrawing group on the aryl groups. The electron-deficient diarylacetylenediol catalysts, while more active, undergo spontaneous cyclization to the corresponding benzo[b]furans. A mechanism is postulated to explain this facile transformation. Computational studies performed on 2-ethynylphenol help to explain the effect of the alkyne on the conformation and hydrogen bond donating ability of the adjacent OH group. Finally, the crystal structure of one of the diols is reported, and it displays an intricate network of intermolecular hydrogen bonds.
- Tuerkmen, Yunus E.,Rawal, Viresh H.
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p. 8340 - 8353
(2013/09/24)
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- Gold-catalyzed cyclizations of (o-alkynyl)phenoxyacrylates with external nucleophiles: Regio-and stereoselective synthesis of functionalized benzo[b]oxepines
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A catalytic approach to benzo[b]oxepines with high stereoselectivity by Au-catalyzed cyclization of (o-alkynyl)phenoxyacrylates with various nucleophiles under mild reaction conditions has been developed. Notably, the use of vinyl ether instead of alcohol could afford the same benzoxepines. The reaction may proceed by Au-catalyzed oligomerization of vinyl ether to release the alcohol, which then reacts with (o-alkynyl)phenoxyacrylates to furnish the benzoxepines.
- Liu, Jun,Liu, Yuanhong
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supporting information
p. 4742 - 4745,4
(2020/09/16)
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- Domino rhodium(I)-catalysed reactions for the efficient synthesis of substituted benzofurans and indoles
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Rhodium(I) catalysts promote the transformation of o-alkynyl phenols and anilines to the corresponding benzo[b]furans and indoles. The reaction is postulated to proceed via a transient 3-rhodium heterocycle intermediate, which can be trapped with suitable electrophiles to give poly-substituted heterocycles. In the case of mono-substituted electron-withdrawn electrophiles, excellent yield and selectivity for conjugate addition versus Heck-Mizoroki reaction can be achieved. In the case of 2-alkynyl pyridine electrophiles, novel 2-(benzofuran-3-yl)vinylpyridines are formed.
- Boyer, Alistair,Isono, Naohiro,Lackner, Sebastian,Lautens, Mark
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supporting information; experimental part
p. 6468 - 6482
(2010/10/03)
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- Rhodium(I)-catalyzed cyclization reaction of o-alkynyl phenols and anilines. Domino approach to 2,3-disubstituted benzofurans and indoles
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A rhodium-catalyzed cyclization of o-alkynylphenols and anilines followed by intermolecular conjugate addition that succeeds with alkyl and aryl alkynes is reported. In this reaction, 2,3-disubstituted benzofurans or indoles are obtained in one pot in good to excellent yields.
- Isono, Naohiro,Lautens, Mark
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supporting information; experimental part
p. 1329 - 1331
(2009/10/02)
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- Antibacterial Agents
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The invention provides compounds of formula (I) and salts thereof: R1-L-R2—B wherein R1, L, R2, and B have any of the values defined herein, as well as compositions comprising such compounds, and therapeutic methods comprising the administration of such compounds or salts. The compounds block siderophore production in bacteria and are useful as antibacterial agents.
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Page/Page column 44
(2009/01/20)
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- Synthesis of aromatic spiroacetals related to γ-rubromycin based on a 3H-spiro[1-benzofuran-2,2′-chromane] skeleton
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The synthesis of a series of aromatic 5,6-benzannelated and naphthyl-benzannelated spiroacetals related to the spiroacetal unit present in the quinonoid antibiotic γ-rubromycin is reported. The key steps include the use of Sonogashira coupling to construct an aryl acetylene that is coupled to an aryl aldehyde forming a propargyl alcohol intermediate. Hydrogenation of the resultant alkynol followed by oxidation produces a masked dihydroxyketone that upon treatment with silica-supported sodium hydrogen sulfate undergoes concomitant deprotection and cyclisation to afford the desired fused aromatic spiroacetal.
- Tsang, Kit Yee,Brimble, Margaret A.
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p. 6015 - 6034
(2008/02/02)
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- Use of a Sonogashira - Acetylide Coupling Strategy for the Synthesis of the Aromatic Spiroketal Skeleton of γ-Rubromycin
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(Equation presented) The synthesis of the fused aromatic spiroketal core of γ-rubromycin is described via addition of an aryl acetylide fragment to an aryl acetaldehyde fragment. In turn, the aryl acetylene precursor was readily prepared with use of a Sonogashira reaction.
- Tsang, Kit Y.,Brimble, Margaret A.,Bremner, John B.
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p. 4425 - 4427
(2007/10/03)
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