Formation of Aromatic Rings through Enamine Annulation

Wang, Chen; Kohn, Harold

doi:10.1021/ol000093p

Cited by 12 publications

(4 citation statements)

References 9 publications

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“…The third generation method has now become the most prevalent one, the original reaction of which was reported in 1983 by Kosugi,4a and the elementary processes involved therein were rationalized in 1994 by Hartwig,4b triggering off modern activity in this area. The present reaction may be a first step toward a potentially useful reaction to make aromatic amines featuring aliphatic-to-aromatic transformation . We could make use of this novel transformation in synthetic objectives which are difficult to achieve relying on the previous methods.…”

Section: Resultsmentioning

confidence: 99%

Aromatization of Enamines Promoted by a Stoichiometric Amount of Palladium(II) Salts: A Novel Method for the Synthesis of Aromatic Amines

et al. 2000

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Enamines (1a-r) prepared from cyclohexanones, cyclohexane-1,3-diones, or tetralones led to arylamines (2a-r) in one pot when treated with a stoichiometric amount of palladium salts [PdCl2-(MeCN)2] in acetonitrile in the presence of triethylamine at room temperature or at elevated temperature, in some cases for 5 min to 2 h. The initial electrophilic attack of palladium chloride on the beta-carbon of the enamines led to a sigma-palladium species (8) which triggered a series of reactions (-->9-->10-->11-->12) destined for aromatization to give 2a-r in good yields. The intervention of such a sigma-palladium species has been attested by a trapping experiment. On the basis of this reaction mechanism, we have developed another new process capable of transforming acyclic compounds having 6-en-2-one frameworks (16, 23, 25) to arylamines (2s-u) when their enamines were treated under the similar conditions as above, featuring again the formation of sigma-palladium species such as 8 as the initial key intermediate.

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Section: Resultsmentioning

confidence: 99%

Aromatization of Enamines Promoted by a Stoichiometric Amount of Palladium(II) Salts: A Novel Method for the Synthesis of Aromatic Amines

et al. 2000

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“…219 Enamine annelation is another method to form benzene rings: dihydrophenanthrene 186 was prepared by condensation of the pyrrolidine enamine of tetralone and 1,4-diacetoxybutan-2-one in moderate yield. 220 It is interesting that the acidification of cyclohexane derivative 187 gives benzene at room temperature. 221…”

Section: (C) Other Reactionsmentioning

confidence: 99%

7 Aromatic chemistry

Toyota

Iyoda

Toda

2002

Annu. Rep. Prog. Chem., Sect. B: Org. Chem.

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“…As a consequence of this observation, we became interested in making further use of this operation for the synthesis of various aryl amines. In this paper we describe the systematic optimization of this benzoannulation reaction and the applicability of the method for the preparation of variously substituted aryl amines and aryl thioethers . It should be noted that a related Robinson annelation of β-keto sulfoxides with vinyl ketones had been reported by Boger and Mullican as a method to prepare highly substituted phenols …”

Section: Introductionmentioning

confidence: 99%

A Benzannulation Protocol To Prepare Substituted Aryl Amines Using a Michael-Aldol Reaction of β-Keto Sulfones

Kiren

Padwa

2009

J. Org. Chem.

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A practical benzannulation method to prepare variously substituted aryl amines and sulfides was developed. The approach involves a Michael-aldol reaction of beta-keto sulfones with enones followed by a subsequent condensation of the initial adduct with various amines. The base-induced Michael-aldol cascade proceeds smoothly with a number of different beta-keto sulfones, affording the adducts as single diastereomers. Heating the resulting Michael-aldol product with an amine in toluene at 120 degrees C results in the formation of a transient enamine, which then undergoes loss of phenyl sulfenic acid to furnish the aromatized amine in good yield. A related reaction also occurred when the Michael-aldol product was heated with thiols or alcohols, giving rise to aryl-substituted sulfides or ethers.

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Formation of Aromatic Rings through Enamine Annulation

Cited by 12 publications

References 9 publications

Aromatization of Enamines Promoted by a Stoichiometric Amount of Palladium(II) Salts: A Novel Method for the Synthesis of Aromatic Amines

Aromatization of Enamines Promoted by a Stoichiometric Amount of Palladium(II) Salts: A Novel Method for the Synthesis of Aromatic Amines

7 Aromatic chemistry

A Benzannulation Protocol To Prepare Substituted Aryl Amines Using a Michael-Aldol Reaction of β-Keto Sulfones

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