Studies with enaminones: reactivity of 1,5‐disubstituted‐1,4‐pentadien‐3‐ones toward electrophilic reagents. a novel route to azolylazines, benzofuranals, pyranones

Al‐Mousawi, Saleh; El‐Sherbiny, Seham; John, Elizabeth; Abdelkhalik, Mervat Mohammed; Elnagdi, Μ. H.

doi:10.1002/jhet.5570380422

Cited by 34 publications

(25 citation statements)

References 8 publications

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“…No trace of the Z-form is observed, only the E-forms were isolated, as had been indicated from the coupling values for olefinic doublets. Several enaminodienones were used as precursors for synthesis of pyridines, pyranones and benzofurans [94]. These reactions occurred through initial attack of α-carbon of enaminodienones 117 on p-benzoquinone, yielding acyclic intermediate 118, with subsequent cyclization exclusively into 119, which is apparently thermodynamically more stable because of its extended conjugated double bond system (Figure 45) Study of annulation reactions of enaminones with various one-and two carbon electrophilic synthons has yielded direct one-pot convergent routes to a variety of functionalized pyrrolo[2,1-α]isoquinolines and indolo[2,1-α] i s oquinolines, and some of them may prove useful precursors for biologically important natural products possessing these structural frameworks [96].…”

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confidence: 99%

Recent development in preparation reactivity and biological activity of enaminoketones and enaminothiones and their utilization to prepare heterocyclic compounds

Negri

Kascheres

2004

Journal of Heterocyclic Chem

179

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Enaminoketones and esters are gaining increased interest, particularly cyclic-β-enaminoesters, which are known as important intermediates for the synthesis of heterocycles and natural products, because the enantioselective preparation of highly functionalized compounds is of central importance in synthetic chemistry. Enaminones are versatile synthetic intermediates that combine the ambident nucleophilicity of enamines with the ambident eletrophilicity of enones. Enaminoketones and enaminonitriles have proven to be versatile building blocks for the synthesis of various heterocycles such as pyridine, pyrimidine and pyrrole derivatives. Enaminones systems have "enone" character, and may act as acceptors in both 1,2 and 1,4-additions. In this way the enaminone serves as a scaffold for annulation, and can gain access to systems such as pyrroles indolizidines, quinolizidines and perhydroindoles, all of which are common motifs in alkaloid structures. Enaminones are frequently employed as building blocks for the preparation of a variety of bicyclic compounds of biological interest and have been recently recognized as potential anticonvulsant compounds. Since a large number of developments in the use of enaminones in heterocyclic synthesis have occurred, a review of the recent developments in the synthetic approaches, covering the literature since 1995 until 2004, to these interesting molecules and their useful chemical transformations and biological activity can be considered of considerable value.J. Heterocyclic Chem., 41, 461 (2004).Enaminoketones. Introduction.The term enaminone was introduced by Greenhill to define the enamine of a 1,3-diketone, β-ketoester or similar 1,3-difunctional reagents, and is used to indicate any compound containing the conjugated system N-C=C-C=O [1]. Enaminones are versatile synthetic intermediates that combine the ambident nucleophilicity of enamines with the ambident eletrophilicity of enones. The chemistry of the enaminocarbonyl group 1 is potentially an area of considerable scope when one considers that there are present in this moiety, three nucleophilic sites (a, c and e) and two electrophilic sites (b and d) [2][3][4] (Figure 1).Theorically, primary and secondary acyclic enaminones can exist in three tautomeric forms: ketamino form, iminoenol form and oxoimino form [1][2][3]. There is also evidence that cyclic enaminones exist primarily in the enaminoketo form. A study of cyclic enaminoketones shows that these compounds have a significant steric fator in the six-membered ring. The six-membered ring enaminoketones are only slightly stronger bases than the saturated amines, whereas five-and-seven membered rings are much stronger bases than saturated amines. This has been attributed to a large steric strain present in six-membered enaminoketones [5].β-Aminoenones or enaminoketones can exist in four conformations owing to restricted rotations around the C=C double and C-C=O single bonds [3]. Enaminones with primary or secondary amino groups can exist in both Z-and E-forms. If there is a...

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confidence: 99%

Recent development in preparation reactivity and biological activity of enaminoketones and enaminothiones and their utilization to prepare heterocyclic compounds

Negri

Kascheres

2004

Journal of Heterocyclic Chem

179

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“…to a cooled dichloromethane solution of azatrienes 1 [19,20] and triethylamine (3eq.). The reactions were found to be highly regioselective leading to the exclusive formation of cycloadducts 5 without any traces of corresponding [2 + 2] adducts 6 (Scheme 1).…”

Section: Resultsmentioning

confidence: 99%

“…The cross-conjugated azatrienes 1 were prepared according to the reported procedure [19,20]. Thionyl chloride and methanesulfonyl chloride used were commercially available.…”

Section: Generalmentioning

confidence: 99%

Cycloaddition Reactions of Azatrienes with Sulfene

Bisetty¹,

Singh²

2012

IJOC

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“…Enamines 39 couple with aromatic diazonium salts to yield 2-arylhydrazonoaldehyde 41 [88][89][90][91][92][93][94][95][96][97][98][99] and arylhydrazonoketones in excellent yield. …”

Section: Methodsmentioning

confidence: 99%

Chemistry of carbofunctionally substituted hydrazones

Dib¹,

Al‐Awadi²,

Elnagdi³

2008

Arkivoc

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Studies with enaminones: reactivity of 1,5‐disubstituted‐1,4‐pentadien‐3‐ones toward electrophilic reagents. a novel route to azolylazines, benzofuranals, pyranones

Abstract: Several new enaminodienones prepared from substituted acetone and dimethylformamide dimethylacetal were used as precursors for synthesis of pyridines, pyranones and benzofurans.

Cited by 34 publications

References 8 publications

Recent development in preparation reactivity and biological activity of enaminoketones and enaminothiones and their utilization to prepare heterocyclic compounds

Recent development in preparation reactivity and biological activity of enaminoketones and enaminothiones and their utilization to prepare heterocyclic compounds

Cycloaddition Reactions of Azatrienes with Sulfene

Chemistry of carbofunctionally substituted hydrazones

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