- Diastereoselective [4 + 1] Cycloaddition of Alkenyl Propargyl Acetates with CO Catalyzed by [RhCl(CO)2]2
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A class of alkenyl propargyl acetates, RCH(OAc)C≡CC(CH 3)=CH2 (5), are found to undergo [4 + 1] cycloaddition with CO (1 atm) in the presence of [RhCl(CO)2]2 in refluxing 1,2-dichloroethane to give cyclopentenones (6) in good yields. It has been demonstrated that, when the R group of 5 is a phenyl group bearing o-electron-withdrawing substituents, up to 10:1 diastereoselectivity and 96% yield can be achieved for the [4 + 1] cycloaddition. This process provides a convenient method to construct highly functionalized cyclopentenones that are useful in organic synthesis.
- Chen, Wei,Tay, Jia-Hui,Yu, Xiao-Qi,Pu, Lin
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experimental part
p. 6215 - 6222
(2012/09/21)
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- Generation and trapping of cyclopentenylidene gold species: Four pathways to polycyclic compounds
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Cyclopentenylidene gold complexes can easily be formed from vinyl allenes through a Nazarov-like mechanism. Such carbenes may transform in four different ways into polycyclic frameworks: electrophilic cyclopropanation, C-H insertion, C-C migration, or proton shift. We have studied the selectivity of these different pathways and used our findings for the expedient preparation of valuable complex molecules. An application to the total synthesis of a natural product, Δ9(12)-capnellene,is presented. DFT computations were carried out to shed light on the me chanisms.
- Lemiere, Gilles,Gandon, Vincent,Cariou, Kevin,Hours, Alexandra,Fukuyama, Takahide,et al.
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supporting information; experimental part
p. 2993 - 3006
(2009/09/04)
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- The Intramolecular Enyne Diels-Alder Reaction. Stereoselective Construction of Tricyclic Dioxadienones and Mechanistic Outline
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4-Methylpent-4-en-2-yn-1-ols and 6-hydroxy-2,3-dihydro-6H-pyran-3-ones are condensed in different ways to a series of tricyclic dioxadienones which contain the basic framework of the cadlinolides A mechanism of the intramolecular enyne-ene cycloisomerization and the origin of the resulting type I and type II dienes is proposed.
- Hoffmann, H. M. R.,Krumwiede, D.,Mucha, B.,Oehlerking, H. H.,Prahst, G. W.
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p. 8999 - 9018
(2007/10/02)
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