Lewis Acid-Induced Intramolecular Friedel−Crafts Cyclization of 1,3-Bis-exocyclic Dienes. A New Route to 4a-Methyltetrahydrofluorenes

Lomberget, Thierry; Bentz, Emilie; Bouyssi, Didier; Balme, Geneviève

doi:10.1021/ol0344265

Cited by 49 publications

(23 citation statements)

References 19 publications

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“…Activation of the alkyne upon coordination to the electrophilic metal19, 21 launches a tosylate migration with a concomitant 1,2‐shift of R 1 that is followed by loss of a proton and a subsequent protiodemetalation to furnish the diene A 14. 22 Next, electrophilic activation of the conjugated diene23 yields a stabilized carbocation B that enters the first electrophilic aromatic substitution event. The resulting cycloisomerization process would render the conversion of 1 into C , which could then further evolve under the reaction conditions.…”

Section: Methodsmentioning

confidence: 99%

Solvent‐Ligated Copper(II) Complexes for the Homopolymerization of 2‐Methylpropene

Voon

Yeong

et al. 2008

Chemistry A European J

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Copper(II) complexes with weakly coordinating counter anions can be utilized as highly efficient catalysts for the synthesis of poly(2-methylpropene) ("polyisobutene") with a high content of terminal double bonds. These copper(II) compounds are significantly more active than the manganese(II) complexes described previously, can be applied in chlorine-free solvents such as toluene, are easily accessible, and can be handled at room temperature and in laboratory atmospheres for brief periods, but they are sensitive to excess water, thereby losing their catalytic activity. Replacing the acetonitrile ligands by benzonitrile ligands improves the solubility and catalytic activity in nonpolar and nonchlorinated solvents. However, the benzonitrile copper(II) compounds have lower thermal stability than their acetonitrile congeners.

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Section: Methodsmentioning

confidence: 99%

Solvent‐Ligated Copper(II) Complexes for the Homopolymerization of 2‐Methylpropene

Voon

Yeong

et al. 2008

Chemistry A European J

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“…[58] A different approach to the intramolecular aromatic alkylation was proposed by Balme and co-workers, who investigated the catalytic Friedel-Crafts cyclization of aryl dienes 63. [59] Here, a series of 4a-methyltetrahydrofluorenes 65 were isolated in moderate to good yield (60-97 %) by employing Sc(OTf) 3 (20 %) in the cyclization of 1,3-bis-exocyclic dienes 63 (Scheme 22). Postulated intermediates of the process could be the electrophilically activated exomethylene species 64a or the conjugate carbocation 64b induced by the metal triflate.…”

Section: Cyclization Of Aryl Alkenesmentioning

confidence: 99%

Innovative Catalytic Protocols for the Ring‐Closing Friedel–Crafts‐Type Alkylation and Alkenylation of Arenes

et al. 2006

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Over the past years an astonishing number of highly chemoand regioselective intramolecular Friedel-Crafts (IMFC)-type alkylations of aromatic compounds have been described in the literature that allow remarkable synthetic shortcuts for the preparation of challenging aromatic compounds. In particular, both transition metal and conventional and unusual Lewis acids (LAs) have been described to promote ring-clos- Index

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“…A wide range of Lewis acids have been tested in this reaction and it was found that a catalytic amount of Sc(OTf) 3 allowed this reaction to proceed. 23 The method was applied to compounds 7b, 15b, 16b and 17b, and was very efficient for constructing the 4a-methyltetrahydrofluorene skeleton 24 that bears electron-donating substituents, an uncommon structure present in some recently isolated natural products 24 (Scheme 7).…”

Section: Intramolecular Friedel-crafts Reactionmentioning

confidence: 99%

New Method for the Synthesis of Functionalized 1,3-Bis-Exocyclic Dienes via a Palladium-Catalyzed Reaction. Scope and Synthetic Applications

Lomberget¹,

Bouyssi²,

Balme³

2005

Synthesis

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The palladium-catalyzed tandem cyclization-coupling reaction of conjugated enynes having a stabilizing carbon nucleophile with aryl iodides and vinyl halides or triflates produced stereodefined, functionalized five-and six-membered 1,3-bis-exocyclic dienes in moderate to good yields. These stereodefined dienes proved to be versatile substrates for the preparation of various polycyclic products through subsequent Diels-Alder, intramolecular Friedel-Crafts or thermal electrocyclization reactions.

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Lewis Acid-Induced Intramolecular Friedel−Crafts Cyclization of 1,3-Bis-exocyclic Dienes. A New Route to 4a-Methyltetrahydrofluorenes

Abstract: [reaction: see text] An efficient new method for constructing the 4a-methyltetrahydrofluorene skeleton was achieved via Friedel-Crafts intramolecular cyclization of 1,3-bis-exocyclic dienes. This strategy offers a simple and promising method for accessing complex structures.

Cited by 49 publications

References 19 publications

Solvent‐Ligated Copper(II) Complexes for the Homopolymerization of 2‐Methylpropene

Solvent‐Ligated Copper(II) Complexes for the Homopolymerization of 2‐Methylpropene

Innovative Catalytic Protocols for the Ring‐Closing Friedel–Crafts‐Type Alkylation and Alkenylation of Arenes

New Method for the Synthesis of Functionalized 1,3-Bis-Exocyclic Dienes via a Palladium-Catalyzed Reaction. Scope and Synthetic Applications

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