Knoevenagel condensation of cyclic ketones with benzoylacetonitrile and N,N′-dimethylbarbituric acid. Application of sterically hindered condensation products in the synthesis of spiro and dispiropyrans by hetero-Diels–Alder reactions

Pałasz, Aleksandra; Pałasz, T.

doi:10.1016/j.tet.2010.12.053

Cited by 31 publications

(14 citation statements)

References 42 publications

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“…These molecules are formed via the Knoevenagel reaction on a large scale. This production results in an extensive range of products for agrochemical and pharmaceutic industries (9,10).…”

Section: Introductionmentioning

confidence: 99%

The Knoevenagel reaction: a review of the unfinished treasure map to forming carbon–carbon bonds

Beurden

Koning

Molendijk

et al. 2020

Green Chemistry Letters and Reviews

124

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The formation of carbon-carbon bonds is a quest that has required a lot of research throughout the last 125 years of history of chemistry. The creation of these bonds is key to producing a wide variety of advanced products with great societal importance. In the past, the Knoevenagel reaction entailed a big part of these reactions. All the Knoevenagel reactions are performed with nitrogen-based catalysts, categorized as tertiary amines, secondary amines, primary amines, and ammonium salts. These catalysts operate through different reaction paths, with very deviant intermediates concerning each category. Subsequently, these intermediates create new research opportunities considering their catalytic activity. Some remarks are made in the context of green chemistry, with quantitative analysis using e-factor calculations. In this perspective, the importance of Knoevenagel chemistry exemplified, which is repeatedly overlooked throughout history.

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“…These molecules are formed via the Knoevenagel reaction on a large scale. This production results in an extensive range of products for agrochemical and pharmaceutic industries (9,10).…”

Section: Introductionmentioning

confidence: 99%

The Knoevenagel reaction: a review of the unfinished treasure map to forming carbon–carbon bonds

Beurden

Koning

Molendijk

et al. 2020

Green Chemistry Letters and Reviews

124

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“…Another example of HDA reaction of 1-oxa-1,3-butadienes is inverse-electron-demand Diels–Alder cycloaddition of sterically hindered cycloalkylidene derivatives of benzoylacetonitrile 17 and derivatives of N , N -dimethylbarbituric acid 20 with enol ethers 18 and cyclic enol ether 22 (Scheme 4 ) [ 77 ]. Spirodihydropyrans 19 , dispirodihydropyrans 23 , spirouracils 21 , and dispirouracils 24 were prepared.…”

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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“…60 The Knoevenagel condensation of cyclic ketones (52) with benzylonitrile (53) and N,N 0 -dimethylbarbituric acid (54) afforded heterodynes (2-cycloalkylidene-3-oxo-3-phenyl-propionitriles 55 and 5-cycloalkylidene-1,3-dimethylpyrimidine-2,4,6-triones 56), which underwent hetero-Diels-Alder cycloaddition reaction with enol ethers (57 and 58) giving sterically hindered dispiropyrans (59, 60) (Scheme 19 and Table 3). 61 Basic conditions of the Suzuki-Miyaura coupling using SiO 2 -supported Pd catalyst 62 could operate in the Knoevenagel condensation under aqueous conditions without the use of amine catalyst. 63 This situation allowed for a combination of the Suzuki-Miyaura coupling of aryl halides 61 and phenylboronic acid (62) A multicomponent reaction between aromatic aldehydes (64), 2-nitromethylenethiazolidine (65), and nitriles 66 in the presence of Et 3 N afforded a series of 5-amino-7-aryl-8-nitrothiazolo[3,2-a]pyridines (67) (Scheme 21, Table 4).…”

Section: One-pot Sequential Reactionsmentioning

confidence: 99%

2.14 Other Condensation Reactions (Knoevenagel, Perkin, Darzens)

Ebitani

2014

Comprehensive Organic Synthesis II

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Knoevenagel condensation of cyclic ketones with benzoylacetonitrile and N,N′-dimethylbarbituric acid. Application of sterically hindered condensation products in the synthesis of spiro and dispiropyrans by hetero-Diels–Alder reactions

Cited by 31 publications

References 42 publications

The Knoevenagel reaction: a review of the unfinished treasure map to forming carbon–carbon bonds

The Knoevenagel reaction: a review of the unfinished treasure map to forming carbon–carbon bonds

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

2.14 Other Condensation Reactions (Knoevenagel, Perkin, Darzens)

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