- Stereoselective synthesis of β-ketoesters from prop-2-yn-1-ols
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The activation of allylic prop-2-yn-1-ols by the [Ru(μ-O2CH)(CO)2(PPh3)]2 catalyst in the presence of carboxylic acids leads to unsaturated β-ketoesters in one step. The utilization of optically active prop-2-yn-1-ols provides a new stereoselective access to optically active β-ketoesters with retention of configuration at the propargylic carbon.
- Darcel, Christophe,Bruneau, Christian,Dixneuf, Pierre H.,Roberts, Stanley M.
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- Ligand-Effect in Gold(I)-Catalyzed Rautenstrauch Rearrangement: Regio- and Stereoselective Synthesis of Bicyclo[3.2.1]octa-3,6-dienes through Cyclodimerization of 1-Ethynyl-2-propenyl Esters
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Gold(I) complexes bearing sterically demanding phosphine ligands such as tBuXphos catalyze the cascade Rautenstrauch rearrangement/[4 + 3] cycloaddition of 1-ethynyl-2-propenyl esters. The reaction provides an efficient and straightforward rout
- Zhao, Jidong,Yang, Shuang,Xie, Xin,Li, Xiangdong,Liu, Yuanhong
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p. 1287 - 1297
(2018/02/09)
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- Rhodium-catalyzed synthesis of 1,2-dihydropyridine by a tandem reaction of 4-(1-acetoxyallyl)-1-sulfonyl-1,2,3-triazole
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A tandem reaction of 4-(1-acetoxyallyl)-1-sulfonyl-1,2,3-triazole including formation of α-imino rhodium carbene, 1,2-migration of an acetoxy group and six electron electrocyclic ring closure was reported. The migration of the OAc group with excellent chemoselectivity was the crucial process, leading to the formation of 1,2-dihydropyridine specifically in up to 90% yield. Several transformations of the dihydropyridine product were also achieved illustrating the potential of the protocol in organic synthesis. Based on the observation of the intermediate, a plausible mechanism was proposed.
- Dai, Haican,Yu, Sisi,Cheng, Wanli,Xu, Ze-Feng,Li, Chuan-Ying
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supporting information
p. 6417 - 6420
(2017/07/10)
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- Asymmetric formal synthesis of (+)-pyrenolide D
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A concise, asymmetric formal synthesis of (+)-pyrenolide D from (E)-crotonaldehyde is described. The key steps include an enantioselective Sharpless dihydroxylation of protected hex-4-en-1-yn-3-ol and a highly diastereoselective palladium-catalysed oxycarbonylation of (2R,3S,4S)-hex-5-ene- 2,3,4-triol using iron pentacarbonyl as the carbon monoxide source. Georg Thieme Verlag Stuttgart · New York.
- Markovic, Martin,Lopatka, Pavol,Koos, Peter,Gracza, Tibor
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p. 817 - 821
(2014/04/03)
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- Simultaneous synthesis of both rings of chromenes via a benzannulation/ o -quinone methide formation/electrocyclization cascade
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A new route to the chromene ring system has been developed which involves the reaction of an α,β-unsaturated Fischer carbene complex of chromium with a propargyl ether bearing an alkenyl group on the propargylic carbon. This transformation involves a cascade of reactions that begins with a benzannulation reaction and is followed by the formation of an o-quinone methide, and finally results in the emergence of a chromene upon an electrocyclization. This reaction was extended to provide access by employing an aryl carbene complex. This constitutes the first synthesis of chromenes in which both rings of the chromene system are generated in a single step and is highlighted in the synthesis of lapachenole and vitamin E.
- Majumdar, Nilanjana,Korthals, Keith A.,Wulff, William D.
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supporting information; experimental part
p. 1357 - 1362
(2012/03/11)
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- Rh-Catalyzed [5+1] and [4+1] cycloaddition reactions of 1,4-enyne esters with co: A shortcut to functionalized resorcinols and cyclopentenones
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We have developed novel Rh-catalyzed [n+1]-type cycloadditions of 1,4-enyne esters, which involve an acyloxy migration as a key step. The efficient preparation of functionalized resorcinols, including biaryl derivatives, from readily available 1,4-enyne esters and CO was achieved by Rh-catalyzed [5+1] cycloaddition accompanied by 1,2-acyloxy migration. When enyne esters had an internal alkyne moiety, the reaction proceeded by a [4+1]-type cycloaddition involving 1,3-acyloxy migration, leading to cyclopentenones.
- Fukuyama, Takahide,Ohta, Yuko,Brancour, Celia,Miyagawa, Kazusa,Ryu, Ilhyong,Dhimane, Anne-Lise,Fensterbank, Louis,Malacria, Max
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supporting information; experimental part
p. 7243 - 7247
(2012/07/03)
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- Synthesis of functionalized resorcinols by rhodium-catalyzed [5+1] cycloaddition reaction of 3-acyloxy-1,4-enynes with CO
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A novel [5+1] type carbonylative cycloaddition reaction has been developed using a Rh complex as catalyst. This reaction can convert readily available 3-acyloxy-1,4-enynes and CO to a wide range of functionalized resorcinols in good yields. A mechanism involving Rh-catalyzed cyclocarbonylation of 3-acyloxy-1,4-enynes accompanied by a 1,2-acyloxy shift is proposed for the present [5+1] type cycloaddition reaction. The Royal Society of Chemistry 2010.
- Brancour, Celia,Fukuyama, Takahide,Ohta, Yuko,Ryu, Ilhyong,Dhimane, Anne-Lise,Fensterbank, Louis,Malacria, Max
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supporting information; experimental part
p. 5470 - 5472
(2010/09/18)
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- Coupling-isomerization synthesis of chalcones
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The Sonogashira coupling of electron-deficient (hetero)aryl halides 1 and (hetero)aryl or alkenyl 1-propargyl alcohols 2 does not terminate at the stage of the expected internal propargyl alcohols, but rather gives rise to the formation of α,β-unsaturated ketones 3 with a variety of acceptor substituents. This new domino reaction, a coupling-isomerization reaction (CIR), can be rationalized as a sequence of rapid Pd/Cu-catalyzed alkynylation followed by a slow amine-base-catalyzed propargyl alcohol-enone isomerization. Performing the CIR in deuterated protic solvents or with a selectively deuterated propargyl alcohol revealed that the base-catalyzed isomerization step proceeds through a formal 1,3-H shift with minimal H/D exchange with the surrounding solvent. Additionally, 19F NMR kinetic measurements on the isomerization step with the fluorinated propargyl alcohol 4r support the mechanistic rationale.
- Braun, Roland U.,Ansorge, Markus,Mueller, Thomas J. J.
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p. 9081 - 9094
(2007/10/03)
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- Carbonylation of Alkynyl Epoxides: Synthesis of 5-Hydroxy-2,3-dienoate Esters and 2,3-Dihydrofuran-3-ol Derivatives
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The carbonylation of alkynyl oxiranes catalyzed by (MePh2)4Pd in the presence of 20 atm of carbon monoxide in methanol gives methyl 5-hydroxy-2,3-pentadienoates in good yields. When the reaction is performed on alkynyl oxiranemethano
- Piotti, Marcelo E.,Alper, Howard
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p. 8484 - 8489
(2007/10/03)
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- NOVEL SYNTHESIS OF ETHYNYL VINYL CARBINOLS AND 2,5-DISUBSTITUTED FURANS FROM ALDEHYDES
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Gem-substituted aryl, aralkenyl and 2-furyl ethynyl vinyl carbinols as well as 2,5-disubstituted furans can be obtained by a novel addition and rearrangement reaction of acetylene with the appropriate aldehydes.
- Hajos, Zoltan G.,Wachter, Michael P.,Werblood, Harvey M.
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p. 3295 - 3300
(2007/10/02)
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- Preparation and use of magnesium acetylene complex
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Preparation of magnesium acetylene complex and its use in preparing ethynyl carbinols.
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