Regiospecific [2+2] cycloadditions of electron-poor acetylenes to (Z)-2-acylamino-3-dimethylaminopropenoates: synthesis of highly functionalised buta-1,3-dienes

Ursic, Uros; Grošelj, Uroš; Meden, Anton; Svete, Jurij; Stanovnik, B.

doi:10.1016/j.tetlet.2008.04.021

Cited by 21 publications

(11 citation statements)

References 19 publications

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“…Nevertheless, if only the position of the β‐substituents is considered, rather than the type, then the analogous structures for ΔAbu and ΔVal residues can be analysed. It has been found that the ΔVal analogues adopt primarily conformations α and β29, 31, 32, 34–40, 42, 43, 45, 50, 53, 55, 58, 60. The conformation β2 can also be found36, 40.…”

Section: Resultsmentioning

confidence: 99%

The conformational properties of α,β‐dehydroamino acids with a C‐terminal ester group

Siodłak

Broda

2011

Journal of Peptide Science

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α,β-Dehydroamino acid esters occur in nature. To investigate their conformational properties, a systematic theoretical analysis was performed on the model molecules Ac-ΔXaa-OMe [ΔXaa = ΔAla, (E)-ΔAbu, (Z)-ΔAbu, ΔVal] at the B3LYP/6-311+ + G(d,p) level in the gas phase as well as in chloroform and water solutions with the self-consistent reaction field-polarisable continuum model method. The Fourier transform IR spectra in CCl(4) and CHCl(3) have been analysed as well as the analogous solid state conformations drawn from The Cambridge Structural Database. The ΔAla residue has a considerable tendency to adopt planar conformations C5 (ϕ, ψ ≈ - 180°, 180°) and β2 (ϕ, ψ ≈ - 180°, 0°), regardless of the environment. The ΔVal residue prefers the conformation β2 (ϕ, ψ ≈ - 120°, 0°) in a low polar environment, but the conformations α (ϕ, ψ ≈ - 55°, 35°) and β (ϕ, ψ ≈ - 55°, 145°) when the polarity increases. The ΔAbu residues reveal intermediate properties, but their conformational dispositions depend on configuration of the side chain of residue: (E)-ΔAbu is similar to ΔAla, whereas (Z)-ΔAbu to ΔVal. Results indicate that the low-energy conformation β2 is the characteristic feature of dehydroamino acid esters. The studied molecules constitute conformational patterns for dehydroamino acid esters with various side chain substituents in either or both Z and E positions.

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Section: Resultsmentioning

confidence: 99%

The conformational properties of α,β‐dehydroamino acids with a C‐terminal ester group

Siodłak

Broda

2011

Journal of Peptide Science

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“…As an extension of our research, we recently reported on microwave assisted regiospecific [2 þ 2] cycloadditions of electron-poor acetylenes 2 to (2Z)-2-(acylamino)-3-(dimethylamino)prop-2-enoates 1, which resulted in the formation of (1E,3E)-1-(acylamino)-4-(dimethylamino)buta-1,3-dienes 3 (Scheme 1) [10].…”

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confidence: 87%

“…-Since (5Z)-5-[(dimethylamino)methylene]imidazolidine-2,4-diones 4a,c and the corresponding thioxo derivative 4b have already been established as very useful intermediates in the synthesis of natural products such a aplysinopsins [4], we report in this article on [2 þ 2] cycloadditions of electron-poor acetylenes 2a -2d to these compounds, which are cyclic analogues of (2Z)-2-(acylamino)-3-(dimethylamino)prop-2-enoates 1 [10].…”

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confidence: 99%

[2+2] Cycloadditions of Electron‐Poor Acetylenes to (5Z)‐5‐[(Dimethylamino)methylene]imidazolidine‐2,4‐diones

Ursic

Grošelj

Meden

et al. 2009

Helvetica Chimica Acta

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Microwave-assisted [2 þ 2] cycloadditions of acetylene mono-and acetylenedicarboxylates 2 to (5Z)-5-[(dimethylamino)methylene]imidazolidine-2,4-dione 4a or to the corresponding thioxo derivative 4b in MeCN furnished the highly functionalized imidazolidine-2,4-dione derivatives 5 and 6 or the corresponding thioxo derivatives 5 -7 as single isomers or mixtures of two isomers (Schemes 2 and 3, Table 1). When the reaction of (5Z)-5-[(dimethylamino)methylene]imidazolidine-2,4-dione (4c) with acetylenedicarboxylate 2a was performed in DMF, hydrolysis of the (dimethylamino)methylene group took place to give (2E)-2-(2,5-dioxoimidazolidin-4-ylidene)butanedioate 11 (Scheme 5).Introduction. -In the last few decades, there have been some reports of reactions of simple tertiary enamines with electron-poor acetylenes, such as alkyl propiolates (¼ alkyl prop-2-ynoates) and dialkyl acetylenedicarboxylates (¼ dialkyl but-2-ynedioates) [1]. It has been generally accepted that these reactions initially proceed by a [2 þ 2] cycloaddition. However, the structure of the final product is strongly dependent on the structure of the starting compound and reaction conditions [1d]. The geometry of the obtained products was, in some cases, unambiguously determined by Reinhoudt and co-workers in the early eighties [1d]. When these reactions were extended to other functionalized enamines and enaminones, in some cases, a Michael-type addition took place preferentially over the [2 þ 2] cycloaddition [2].The 3-(dimethylamino)propenoates and related enaminones have been demonstrated to be useful building blocks in the synthesis of many heterocyclic systems [3], including the preparation of natural products and their analogs, such as aplysinopsins [4], meridianines [5], dipodazines [6], and tryprostatins [7]. We have also reported an efficient method for the preparation and functionalization of highly substituted 1amino-2,3-dihydro-1H-pyrrole, 1-amino-1H-pyrrole, and fused pyrrolo[3,2-d]oxazole systems from 1,2-diazabuta-1,3-dienes and 3-(dimethylamino)prop-2-enoates [8] and the regio-and stereoselective one-pot synthesis of oxazolo-fused pyridazines via a Michael-addition -pyridazine-cyclization -oxazoline cyclization cascade reaction [9].As an extension of our research, we recently reported on microwave assisted regiospecific [2 þ 2] cycloadditions of electron-poor acetylenes 2 to (2Z)-2-(acylamino)-3-(dimethylamino)prop-2-enoates 1, which resulted in the formation of (1E,3E)-1-(acylamino)-4-(dimethylamino)buta-1,3-dienes 3 (Scheme 1) [10].

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“…2-Amino-3-dimethylaminopropenoates were reacted with acetylene derivatives to furnish eventually 1-amino-4-(dimethylamino)buta-1,3-diene derivatives (76) (Scheme 2.55). The reaction takes place via a cyclobutene intermediate (75) by retro-electrocyclisation [89].…”

Section: [2+2] Cycloadditionsmentioning

confidence: 99%

“…Kočevar developed an efficient synthesis of 1,5,6-trisubstituted indoles involving two MW-assisted steps. The first step is the Diels-Alder cycloaddition reaction between (Z)-1-methoxybut-1-en-3-yne with 2H-pyran-2-ones (88) yielding substituted aniline derivatives (89). In the next step, the adducts underwent intramolecular cyclization under acidic conditions to give the corresponding indole derivatives (90) (Scheme 2.64).…”

Section: Diels-alder Cycloadditionsmentioning

confidence: 99%

Microwave-Assisted Syntheses in Organic Chemistry

Kiss

Bálint²,

Keglevich

2016

SpringerBriefs in Molecular Science

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The second part focuses on the summary of typical organic chemical reactions selected, such as coupling reactions (C-C bond formation reactions, carbon-heteroatom bond formations), condensations (aldol-type-, Claisen-, Knoevenagel reaction), multicomponent reactions (Mannich-, Biginelli-, Hantzsch-, Bucherer-Bergs-, Strecker-, Gewald-, Kabachnik-Fields-, Kindler-, Passerini-, Ugi-and domino reactions), cycloadditions (including Diels-Alder reactions). The authors tried to compile fashionable reactions that have been reviewed less in the past years.

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Regiospecific [2+2] cycloadditions of electron-poor acetylenes to (Z)-2-acylamino-3-dimethylaminopropenoates: synthesis of highly functionalised buta-1,3-dienes

Cited by 21 publications

References 19 publications

The conformational properties of α,β‐dehydroamino acids with a C‐terminal ester group

The conformational properties of α,β‐dehydroamino acids with a C‐terminal ester group

[2+2] Cycloadditions of Electron‐Poor Acetylenes to (5Z)‐5‐[(Dimethylamino)methylene]imidazolidine‐2,4‐diones

Microwave-Assisted Syntheses in Organic Chemistry

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