A novel synthesis of 2,3-dihydro-7(1H)-indolizinones

Gravestock, David; Peirson, Ian G.

doi:10.1016/s0040-4039(00)00406-8

Cited by 10 publications

(8 citation statements)

References 11 publications

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“…Tertiary enaminones were shown to exist in the t r a n s-s -t r a n s c o n f o r m a t i o n . Comparison of 1 H NMR data with literature values showed that enaminones 3 2 were obtained as the E-isomers [34].…”

Section: Miscellaneousmentioning

confidence: 71%

Recent Development in Preparation Reactivity and Biological Activity of Enaminoketones and Enaminothiones and Their Utilization to Prepare Heterocyclic Compounds

Negri¹,

Kascheres²,

Kascheres³

2004

ChemInform

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Section: Miscellaneousmentioning

confidence: 71%

Recent Development in Preparation Reactivity and Biological Activity of Enaminoketones and Enaminothiones and Their Utilization to Prepare Heterocyclic Compounds

Negri¹,

Kascheres²,

Kascheres³

2004

ChemInform

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“…Secondary enaminones had been shown to exist in the c i s-s -c i s configuration, which allowed intramolecular hydrogen bonding resulting in a very stable six-membered ring. Tertiary enaminones were shown to exist in the t r a n s-s -t r a n s c o n f o r m a t i o n .Comparison of 1 H NMR data with literature values showed that enaminones 3 2 were obtained as the E-isomers [34].Reaction of 4-hydroxycoumarin 33 with ethylorthoformate, phenylhydrazine and p-tolyl-hydrazine yielded the anilino-methylene chromandiones (enaminoketone) 3 4, which indicated a reductive N-N bond cleavage to aniline and ammonia under mild conditions ( Figure 16) [35].S c h i ff bases derived from tryptophan methyl ester 3 5 reacted with differently substituted electron-rich siloxy dienes 36 in a domino Mannich-Michael process in the presence of achiral or chiral boric acid and gave enaminones (vinylogous amides) 37 and 38 ( Figure 17). In this sequential transformation the silylenol ether of the diene attacked the imine first and gave rise to a vinylogous ester which cyclizes by conjugated attack of the amine on the carbonyl group [36].…”

mentioning

confidence: 85%

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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“…4 Indolizinones have been prepared by using a variety of protocols which includes the palladium catalysed domino reaction of tertiary propargylic alcohols, 5 copper-catalyzed cycloisomerization of 2-pyridylsubstituted propargylic acetates, 6 Au-catalyzed synthesis from N-(pent-2-en-4-ynyl)-lactams 7 etc., but most of them require expensive 5,7,8 and toxic metal catalysts, 9 molecular VOLs (volatile organic liquids) as a reaction medium, 10 and have a tedious work-up process. 11 Recently, a few relatively greener protocols have also been employed for the synthesis of indolizinones. 12 But, there is still need for the development of a straightforward, efficient, high yielding, atom economical, ecocompatible synthetic protocol for indolizinones.…”

Section: Introductionmentioning

confidence: 99%

[bmim]OH promoted hydroalkynylation of nitrile and intramolecular hydroamination of the carbon–carbon multiple bond: an efficient and eco-compatible strategy for the synthesis of indolizinones

et al. 2013

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An efficient and novel hydroalkynylation of 2-cyanopyridine with arylacetylene and a subsequent intramolecular hydroamination promoted by a basic ionic-liquid, [bmim]OH, under microwave activation in the absence of an organic solvent and an inorganic base, yielding biodynamic indolizinones has been developed. The protocol involves [bmim]OH mediated in situ generation and addition of a nucleophilic alkynide from the aryl substituted terminal on a carbon alkyne of a polar nitrile group of 2-cyanopyridine. This results in the formation of a 2-pyridylphenylethynyl methimine intermediate which, on subsquent intramolecular nucleophilic addition of a pyridyl nitrogen on the carbon-carbon triple bond of the imine intermediate, heterocyclized into indolizinone with high atom economy. The reaction proceeded smoothly and quantitatively at an ambient temperature. The task specific [bmim]OH was recovered and reused three times without any appreciable decrease in its activity and product yield.

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A novel synthesis of 2,3-dihydro-7(1H)-indolizinones

Cited by 10 publications

References 11 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

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

[bmim]OH promoted hydroalkynylation of nitrile and intramolecular hydroamination of the carbon–carbon multiple bond: an efficient and eco-compatible strategy for the synthesis of indolizinones

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