Synthesis of 3,4-dihydro-2H-pyrans by hetero-Diels–Alder reactions of functionalized α,β-unsaturated carbonyl compounds with N-vinyl-2-oxazolidinone

Pałasz, Aleksandra

doi:10.1039/b504210k

Cited by 31 publications

(9 citation statements)

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“…The scope of intermolecular HDA reactions of 1-oxa-1,3-butadienes with inverse-electron-demand was expanded to cycloadditions with enecarbamate [78]. Cycloadditions of 3-aryl-2-benzoylprop-2-enenitriles and 3-phenylsulfonylbut-3-en-2-ones 25 to N -vinyl-2-oxazolidinone 26 proceeded regio- and diastereoselectively, yielding cis 27 and trans 28 diastereoisomers of 3,4-dihydro-2-(2-oxo-3-oxazolidinyl)-2 H -pyrans in 37–65 % yield (Scheme 5).…”

Section: Inverse-electron-demand Hetero-diels–alder Reactions Of 1-oxmentioning

confidence: 99%

Recent Advances in Inverse-Electron-Demand Hetero-Diels–Alder Reactions of 1-Oxa-1,3-Butadienes

Pałasz

2016

Top Curr Chem (Z)

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This review is an endeavor to highlight the progress in the inverse-electron-demand hetero-Diels–Alder reactions of 1-oxa-1,3-butadienes in recent years. The huge number of examples of 1-oxadienes cycloadditions found in the literature clearly demonstrates the incessant importance of this transformation in pyran ring synthesis. This type of reaction is today one of the most important methods for the synthesis of dihydropyrans which are the key building blocks in structuring of carbohydrate and other natural products. Two different modes, inter- and intramolecular, of inverse-electron-demand hetero-Diels–Alder reactions of 1-oxadienes are discussed. The domino Knoevenagel hetero-Diels–Alder reactions are also described. In recent years the use of chiral Lewis acids, chiral organocatalysts, new optically active heterodienes or dienophiles have provided enormous progress in asymmetric synthesis. Solvent-free and aqueous hetero-Diels–Alder reactions of 1-oxabutadienes were also investigated. The reactivity of reactants, selectivity of cycloadditions, and chemical stability in aqueous solutions and under physiological conditions were taken into account to show the potential application of the described reactions in bioorthogonal chemistry. New bioorthogonal ligation by click inverse-electron-demand hetero-Diels–Alder cycloaddition of in situ-generated 1-oxa-1,3-butadienes and vinyl ethers was developed. It seems that some of the hetero-Diels–Alder reactions described in this review can be applied in bioorthogonal chemistry because they are selective, non-toxic, and can function in biological conditions taking into account pH, an aqueous environment, and temperature.

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Section: Inverse-electron-demand Hetero-diels–alder Reactions Of 1-oxmentioning

confidence: 99%

Recent Advances in Inverse-Electron-Demand Hetero-Diels–Alder Reactions of 1-Oxa-1,3-Butadienes

Pałasz

2016

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“…The only products and C-7 of the dihydropyran ring in the 1 H NMR spectra ( Figure 2, Table 9). In previous papers, 22,23 it was shown that reactions 5-arylidene-N,N-dimethylbarbituric acids with styrenes or N-vinyl-2-oxazolidinone required refluxing in toluene for 24-36 hours for styrenes 22 and 3-5 hours for N-vinyl-2-oxazolidinone. 23 The reactions performed 'on water' in heterogeneous phase were faster (1-3 h) than those executed in refluxing toluene solution.…”

Section: Figurementioning

confidence: 99%

“…In previous papers, 22,23 it was shown that reactions 5-arylidene-N,N-dimethylbarbituric acids with styrenes or N-vinyl-2-oxazolidinone required refluxing in toluene for 24-36 hours for styrenes 22 and 3-5 hours for N-vinyl-2-oxazolidinone. 23 The reactions performed 'on water' in heterogeneous phase were faster (1-3 h) than those executed in refluxing toluene solution. The 'on-water' reactions were characterized by very high endo/exo diastereoselectivity in contrast to reactions in boiling toluene for which a cis/trans diastereoselectivity of 1:1 was observed.…”

Section: Figurementioning

confidence: 99%

A Green Approach to the Synthesis of Fused Uracils: Pyrano[2,3-d]pyrimidines. ‘On-Water’ One-Pot Synthesis by Domino Knoevenagel/Diels-Alder Reactions

Pałasz¹

2010

Synthesis

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On-water' Knoevenagel condensations of 2-thiobarbituric acid and N,N-dimethylbarbituric acid with aromatic and heteroaromatic aldehydes were carried out without a catalyst and at room temperature. Condensations in aqueous suspensions occurred rapidly, giving excellent yields. Solvent-free hetero-Diels-Alder reactions of 5-arylidene derivatives of barbituric acids with ethyl vinyl ether were investigated at room temperature and pyrano [2,3-d]pyrimidines of potential pharmacological activity were obtained in excellent yields. Three-component one-pot syntheses of annulated uracils were performed in aqueous suspensions. Reactions of barbituric acids, aldehydes, and ethyl vinyl ether were carried out at ambient temperature, whereas the one-pot synthesis with barbituric acids, aldehydes, and styrene or N-vinyl-2-oxazolidinone required the heating of aqueous suspensions at 60°C. 'On-water' cycloadditions were characterized by high diastereoselectivity in contrast to reactions carried out in homogeneous organic media (dichloromethane, toluene). They allowed the cis adducts to be obtained preferentially or exclusively. The presented green methods avoid the use of catalysts, the heating of reaction mixtures for long times at high temperatures, and the use of organic solvents, and make the synthesis of a variety of pyrano[2,3-d]pyrimidines chemically efficient. The results reveal water as the medium of choice for the examined cycloadditions.Water is the solvent of choice for nature to carry out syntheses of complex organic molecules. Water is a clean, inexpensive, environmentally friendly reaction medium. Therefore the choice of water as solvent for organic reactions in the laboratory is obvious. However, water as a solvent was ruled out from organic reactions during the preceding decades. The situation changed in 1980 by the pioneering work of Breslow and Rideout, who demonstrated that Diels-Alder reactions of water-soluble reagents would be greatly accelerated in aqueous solution. 1a In 2005, Sharpless and co-workers demonstrated that the Diels-Alder reaction of the water-insoluble reactants showed substantial rate acceleration in aqueous suspension over homogeneous solution. 1b Hydrophobic interactions of reagents with water are invoked for the observed effects.Barbituric acids and their derivatives are reported to have a wide range of pharmacological activities. For example, 5,5-disubstituted derivatives, known as barbiturates, are a family of valuable drugs that depress nerve activity. 2 5-Arylidene derivatives of barbituric acids are bioactive compounds 3 and are also important intermediates in the preparation of other pharmaceuticals, for example annulated uracils. Uracil and its fused derivatives, such as pyrano[2,3-d]pyrimidines, pyrido[2,3-d]pyrimidines, pyrazo[3,4-d]pyrimidines, or pyrimido[4,5-d]pyrimidines, are reported to have a wide range of biological activities such as antiallergic, 4 antihypertensive, 5 cardiotonic, 6 bronchiodilator, 7 antibronchitic, 8 or antitumor 9 activity.The preparation of the above...

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“…Pyranes and cyclic ketones are biologically active compounds to make up a structural part of natural compounds [1][2]. New [4+2] annulations were carried out in the presence of triphenylphosphine catalyst and high yield synthesized functionalized dihydropyranes [3].…”

Section: Introductionmentioning

confidence: 99%

The Investigation of Reaction of Various Thiophene Based Knoevenagel Adducts With Acetoacetanilide

Naghiyev¹,

Maharramov²,

Asgarova³

et al. 2018

Chemical Problems

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The reaction of Michael addition interaction of 3-phenyl-2-(thiophene-2-carbonyl)acrylonitrile, 2-(thiophene-2-carbonyl)-3-(p-tolyl)acrylonitrile, 3-(4-methoxyphenyl)-2-(thiophene-2-carbonyl)acrylonitril, as well as 3-pyridinyl-2-(thiophene-2-carbonyl)acrylonitrile with acetoacetanilide made it possible to produce substituted hexanones and 3,4-dihydro-2H-pyrane derivatives. Structures of synthesized compounds were acknowledged by NMR and X-Ray structural analysis.

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Synthesis of 3,4-dihydro-2H-pyrans by hetero-Diels–Alder reactions of functionalized α,β-unsaturated carbonyl compounds with N-vinyl-2-oxazolidinone

Cited by 31 publications

References 32 publications

Recent Advances in Inverse-Electron-Demand Hetero-Diels–Alder Reactions of 1-Oxa-1,3-Butadienes

Recent Advances in Inverse-Electron-Demand Hetero-Diels–Alder Reactions of 1-Oxa-1,3-Butadienes

A Green Approach to the Synthesis of Fused Uracils: Pyrano[2,3-d]pyrimidines. ‘On-Water’ One-Pot Synthesis by Domino Knoevenagel/Diels-Alder Reactions

The Investigation of Reaction of Various Thiophene Based Knoevenagel Adducts With Acetoacetanilide

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