1,2‐Alkyl Migration as a Key Element in the Invention of Cascade Reactions Catalyzed by π‐Acids

Crone, Benedikt; Kirsch, Stefan F.

doi:10.1002/chem.200701985

Cited by 200 publications

(69 citation statements)

References 121 publications

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“…54 Among these transformations, transition-metal induced cyclizations are generally applied to give cationic intermediates, which are terminated by subsequent semipinacol rearrangements. This type of reaction possesses the following features: (1) The hydroxyl group is always protected as silyl ether to prevent competitive heterocyclization.…”

Section: Other Tandem Versionmentioning

confidence: 99%

3.16 The Semipinacol Rearrangements

Wang¹,

Tu²,

Tang³

2014

Comprehensive Organic Synthesis II

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Section: Other Tandem Versionmentioning

confidence: 99%

3.16 The Semipinacol Rearrangements

Wang¹,

Tu²,

Tang³

2014

Comprehensive Organic Synthesis II

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“…[25] In these reactions, geminal carbo-functionalization through initial 5-exo cyclization gave a bicyclic carbene complex such as I, which underwent 1,2-alkyl migration of the benzylic carbon to give the product with regeneration of the catalyst. [26] During these studies, we thought of the possibility-based on previous experimental results [27] -of geminal carbo-functionalization through initial 6-endo cyclization in the presence of tungsten catalyst. Surprisingly, treatment of 11 a with [ReCl(CO) 5 ] (10 mol %) gave a 78 % yield of the tricyclic compounds 13 a and 14 a (Table 10), produced by insertion of the carbene complex moiety into the neighboring C À H bonds in the carbene complex intermediate generated by 5-exo cyclization.…”

Section: Introductionmentioning

confidence: 99%

Tungsten(0)‐ and Rhenium(I)‐Catalyzed Tandem Cyclization of Acetylenic Dienol Silyl Ethers Based on Geminal Carbo‐Functionalization of Alkynes

Kusama

Karibe

Imai

et al. 2011

Chemistry A European J

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Tungsten(0)- and rhenium(I)-catalyzed reactions of acetylenic dienol silyl ethers based on the concept of geminal carbo-functionalization of alkynes are reported. Treatment of 3-siloxy-1,3-diene-7-ynes with catalytic amounts of [W(CO)(6)] or [ReCl(CO)(5)] under photoirradiation conditions gives synthetically useful bicyclo[3.3.0]octane derivatives in good yields. Extremely high catalytic activity is noted for the rhenium(I) complex. The reaction has been extended to substrates containing a nitrogen atom in their tethers. In this case, two kinds of synthetically useful heterocyclic compounds-the 2-azabicyclo[3.3.0]octane derivatives 9 and the monocyclic dihydropyrroles 10, with allenyl substituents-are obtained, and selective preparation of either product can be achieved through the use of an appropriate combination of the nitrogen substituent and the type of the rhenium(I) catalyst. The 2-azabicyclo[3.3.0]octane derivatives 9 are obtained selectively by carrying out treatment of N-Ns derivatives in the presence of [ReCl(CO)(4)(PPh(3))], whereas the dihydropyrrole derivatives 10 are obtained by treatment of N-Mbs derivatives with [ReCl(CO)(5)]/AgSbF(6) . Finally, we have applied this geminal carbo-functionalization to one-carbon-elongated substrates containing N-Ts moieties in their tethers. Selective 5-exo cyclization is achieved in the presence of gold(I) or rhenium(I) catalysts, whereas 6-endo cyclization is observed on use of [W(CO)(6)].

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“…[3] One of the most interesting features is the ability to act as a mild, relatively carbophilic π Lewis acid. [4] π Bonds activated by gold can undergo a variety of reactions such as the addition of nucleophiles, migration of propargyl and other esters, 1,2 migrations, [5] or cyclo isomerizations of enynes for example. [6] Redox reactions under homogeneous conditions are less frequently disclosed compared to the vast number of Au cata lyzed reactions.…”

Section: Introductionmentioning

confidence: 99%

Oxidative Coupling Reactions with Gold

Wegner

2009

Chimia

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.Abstract: Oxidative coupling reactions are a very powerful tool for the construction of e.g. biaryl compounds, especially because typically no functionalization of the coupling partners is necessary. The use of Au for this transformation is particularly attractive since usually no special precautions to exclude moisture or air are necessary. Furthermore, the combination of oxidative coupling reactions with other Au-catalyzed reactions enables the rapid and efficient construction of molecular complexity, e.g. the constructions of dicoumarins via a domino cyclization oxidative coupling reaction.

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1,2‐Alkyl Migration as a Key Element in the Invention of Cascade Reactions Catalyzed by π‐Acids

Cited by 200 publications

References 121 publications

3.16 The Semipinacol Rearrangements

3.16 The Semipinacol Rearrangements

Tungsten(0)‐ and Rhenium(I)‐Catalyzed Tandem Cyclization of Acetylenic Dienol Silyl Ethers Based on Geminal Carbo‐Functionalization of Alkynes

Oxidative Coupling Reactions with Gold

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