The Emergence of Allenamides in Organic Synthesis

Wei, Lin-li; Xiong, Hui; Hsung, Richard P.

doi:10.1021/ar030029i

Cited by 354 publications

(65 citation statements)

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“…The major question here is how viable is it to access conjugated dienes from structurally more challenging allenes through a kinetically difficult and stereochemically undistinguished isomerization. It might not seem like a logical approach; however, our justification is that since there are few well established routes for preparing amido-dienes, our allenamide isomerization strategy (for reviews on allenamide chemistry see [21–23], for reports in 2009, 2010 and 2011 see [24–43], for earlier studies on allenamides see [44–46]) can open the door to construct synthetically useful amido-dienes (for a review on the synthesis of enamides see [47], for reviews on the chemistry of dienamides see [48–50], for reviews on the chemistry of 2-amino or 2-amido-dienes see [51–52]). Problems with the two primary approaches to access amido-dienes [47] are that acid-mediated condensations suffer from functional group tolerances, and metal-mediated coupling methods (for reviews on Cu-mediated C–N and C–O bond formations see [53–55], for some examples see [56–58]) suffer from limited access as well as the instability of halo-dienes (Scheme 2).…”

Section: Introductionmentioning

confidence: 99%

An efficient and practical entry to 2-amido-dienes and 3-amido-trienes from allenamides through stereoselective 1,3-hydrogen shifts

Hayashi¹,

Feltenberger²,

Lohse³

et al. 2011

Beilstein J. Org. Chem.

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SummaryPreparations of de novo acyclic 2-amido-dienes and 3-amido-trienes through 1,3-hydrogen shifts from allenamides are described. These 1,3-hydrogen shifts could be achieved thermally or they could be promoted by the use of Brønsted acids. Under either condition, these processes are highly regioselective in favour of the α-position, and highly stereoselective in favour of the E-configuration. In addition, 6π-electron electrocyclic ring-closure could be carried out with 3-amido-trienes to afford cyclic 2-amido-dienes, and such electrocyclic ring-closure could be rendered in tandem with the 1,3-hydrogen shift.

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Section: Introductionmentioning

confidence: 99%

An efficient and practical entry to 2-amido-dienes and 3-amido-trienes from allenamides through stereoselective 1,3-hydrogen shifts

Hayashi¹,

Feltenberger²,

Lohse³

et al. 2011

Beilstein J. Org. Chem.

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“…Allenamides represent a fascinating and versatile functional group whose chemical utility has been exploited by a number of groups. 13 The The use of gold salts for the activation of allenamides is an attractive concept as it would negate the use of acidic conditions for allenamide activation 24 and would therefore be more functional group tolerant. 25 It is in this class of reactions, catalyzed by gold salts, in which we thought we could make a contribution within the context of direct intermolecular arylations (Scheme 2).…”

Section: Enamidementioning

confidence: 99%

A Facile and Mild Synthesis of Enamides using a Gold-Catalyzed Nucleophilic Addition to Allenamides

Kimber

2010

Org. Lett.

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“…[1][2][3][4][5][6][7][8] Among them, α-allenyl carbonyl compounds are important building blocks for a variety of organic transformations. Cycloisomerization of allenyl ketones (Chart 1) in the presence of a transition metal catalyst is an efficient way to build substituted furans.…”

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confidence: 99%

Tandem Reaction of Enynyl Acetate: Precursor of Allenyl Ketones

Okamoto

Sueda

Yanada

2016

CHEMICAL & PHARMACEUTICAL BULLETIN

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Deacetylation of enynyl acetates under basic conditions allows convenient access to reactive allenyl ketones, which can then undergo 1,4-addition of nucleophiles to furnish β,γ-unsaturated ketones. Benzofuran and indole derivatives have also been obtained from enynyl acetates with an o-hetero-atom-substituted aryl group via intramolecular 1,4-addition.Key words alkyne; allenyl ketone; tandem reaction; enynyl acetate; furan; indole Reactions of functionalized allenes have been investigated in the past two decades.1-8) Among them, α-allenyl carbonyl compounds are important building blocks for a variety of organic transformations. Cycloisomerization of allenyl ketones (Chart 1) in the presence of a transition metal catalyst is an efficient way to build substituted furans.9-16) It was first reported by Marshall and Robinson 9) and later by Hashmi. 11) In 2003, Gevorgyan and colleagues reported copper-catalyzed cycloisomerization of thioallenylketones via 1,2-migration of the thiogroup 17) and later developed a series of metal-catalyzed 1,2-migration/cycloisomerization methodology toward multisubstituted 3-seleno-, 18) acyloxy-, 19) halo-, 20) aryl-, and alkyl-furans. 21) In some of those studies, alkynyl ketones or propargyl ketones were used as precursors of allenylketones, involving propargyl-allenyl isomerization prior to 1,2-migration/cycloisomerization. 13,15,16) During the course of our study on exploration of a new tandem reaction triggered by the reactivity of an alkyne triplebond, we reported multisubstituted furan formation from (E)-or (Z)-enynyl acetates, 22) which were prepared regio-and stereoselectively by Sonogashira coupling reaction of (E)-or (Z)-iodoenyl acetates, obtained from the reaction of alkyne with N-iodosuccinimide (NIS) and acetic acid 23) (Chart 2). Treatment of (E)-enynyl acetates 2 and (Z)-enynyl acetates 3 with NIS afforded multisubstituted furans 5 via the common iodoallenyl ketones 4 regardless of the double-bond geometry of starting enynyl acetate.24) The proposed reaction pathway involves the formation of iodoallenyl ketone 4 by electrophilic addition of NIS to the triple-bond of enynyl acetate followed by 1,2-halogen migration 20) of the resulting iodoallenyl ketone and cycloisomerization.This result encouraged us to explore the possibility of enynyl acetates as precursors of allenyl ketones and application for a new tandem reaction. Hammond and colleagues reported regioselective reactions of alkynyl enolate 25,26) in which alkynyl enolates were generated by deprotonation of allenyl ketone or propargyl ketone. We hypothesized that

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The Emergence of Allenamides in Organic Synthesis

Abstract: This Account highlights recent studies describing utility of allenamides in stereoselective inter- and intramolecular synthetic methodologies. It is written to raise interest in the chemistry of allenamides.

Cited by 354 publications

References 71 publications

An efficient and practical entry to 2-amido-dienes and 3-amido-trienes from allenamides through stereoselective 1,3-hydrogen shifts

An efficient and practical entry to 2-amido-dienes and 3-amido-trienes from allenamides through stereoselective 1,3-hydrogen shifts

A Facile and Mild Synthesis of Enamides using a Gold-Catalyzed Nucleophilic Addition to Allenamides

Tandem Reaction of Enynyl Acetate: Precursor of Allenyl Ketones

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