An examination of β-enolization in benzobicyclo[2.2.2], [3.2.1], and [3.2.2] ketones

Noncoordinating solvents permit the halogen-metal exchange-induced formation of benzyne (aryne) from di- and trihalobenzene precursors in the presence of cyclopentadiene to give 1,4-dihydro-1,4-methano-naphthalenes. Studies with mixed halide precursors and nonacidic Diels-Alder diene traps reveal that ethereal and hydrocarbon solvents influence the halide leaving group facility, resulting in a reversal of 3-halobenzyne regioselectivity.

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“…These yields are comparable to those in previously reported Grignard approaches to unsubstituted products. See ref .…”

Section: Referencesmentioning

confidence: 99%

Formation of 3-Halobenzyne: Solvent Effects and Cycloaddition Adducts

et al. 2004

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“…We wish to describe here 'part 146 of the series I3cmr studies; for Part 145 see ref. 33. 2~resent address: Malti-Chem Research Centre, Nandesari, India.…”

Section: Introductionmentioning

confidence: 99%

Rearrangements of tricyclic ketones: [3.3.3]propellane formation via a γ-enolate revealed in an approach to the pentalenene skeleton through β-enolization

Patel¹,

Stothers²,

Thomas³

1994

Can. J. Chem.

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The known isomerization of the tricyclo[5.3.1.01,5]- to the [6.3.0.01,5]undecane skeleton by β-homoenolization led to examination of 2,9,9-trimethyl-6-methoxymethyltricyclo[5.3.1.01,5]undecanone (6) as a potential precursor for the synthesis of pentalenene, a naturally occurring sesquiterpenoid, utilizing a β-enolate rearrangement as a key step. While the anticipated rearrangement of 6 occurs, it is a minor process. The major rearrangement product arises by generation of a γ-enolate intermediate from a tricyclic enone formed by loss of methanol from 6. This constitutes a new route to [3.3.3]propellanes and provides a third example of γ-enolate rearrangement. Structures of the products were established primarily from their 1H and 13Cmr spectra.

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Haller‐Bauer Cleavage

2010

Comprehensive Organic Name Reactions and Reagents

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Haller–Bauer cleavage is the base induced cleavage of a carbon‐carbon bond of a nonenolizable ketone to give a carboxylic acid derivative and a neutral fragment in which the carbonyl group is replaced by hydrogen. It has also reported that this reaction overwhelmingly involves a carbanion and the mode of cleavage depends on the relative stability of the carbanions involved. Some exceptions have also been represented which result in reverse cleavage because of the steric interaction. The metal cation of used bases are found to affects this reaction. This reaction has been extended to use potassium t ‐butoxide or N ‐alkylamines and N , N ‐dialkylamines to induce the cleavage. This reaction has been used in the preparation of tertiary carboxamides, tertiary alcohols, and debenzoylation.

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An examination of β-enolization in benzobicyclo[2.2.2], [3.2.1], and [3.2.2] ketones

Cited by 9 publications

References 15 publications

Formation of 3-Halobenzyne: Solvent Effects and Cycloaddition Adducts

Formation of 3-Halobenzyne: Solvent Effects and Cycloaddition Adducts

Rearrangements of tricyclic ketones: [3.3.3]propellane formation via a γ-enolate revealed in an approach to the pentalenene skeleton through β-enolization

Haller‐Bauer Cleavage

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