223. Hydroxy-carbonyl compounds. Part VII. Coumarins and 1 : 4-benzopyrones derived from m-cresol

Robertson, Alexander; Waters, Roy Basil; Jones, Elfed Thomas

doi:10.1039/jr9320001681

Cited by 24 publications

(9 citation statements)

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“…Robertson and coworkers extended the investigation to other phenols with similar results; they found that resorcinol, phloroglucinol, pyrogallol (33), and a-naphthol (173) always gave coumarins, irrespective of the condensing agent used. Robertson and coworkers (175) studied different phenols with a view to investigating whether coumarins or chromones are formed in the presence of phosphorus pentoxide. They concluded that the Simonis reaction depends entirely on the nature of the phenol and is independent of the nature of the ester, a view which was modified by them later on.…”

Section: B Condensing Agentsmentioning

confidence: 99%

The Chemistry of Coumarins.

Sethna¹,

Shah²

1945

Chem. Rev.

295

123

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Section: B Condensing Agentsmentioning

confidence: 99%

The Chemistry of Coumarins.

Sethna¹,

Shah²

1945

Chem. Rev.

295

123

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“…The presence of 4-methylcoumarin and its intermediates in the reaction mixture was confirmed by HPLC-MS measurements. The reaction pathway follows the mechanism proposed by Robertson et al [ 40 ] as illustrated in Scheme 3 . Ethyl acetoacetate is chemisorbed on the acid sites of the catalyst.…”

Section: Resultsmentioning

confidence: 96%

Coumarin Derivatives Solvent-Free Synthesis under Microwave Irradiation over Heterogeneous Solid Catalysts

et al. 2017

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A suitable methodology of synthesis of coumarin derivatives by Pechmann reaction over heterogeneous solid acid catalysts in a free solvent media under microwave irradiation is described. Resorcinol, phenol and ethyl acetoacetate were selected as model reactants in the Pechmann condensation. The catalytic activity of several materials—Amberlyst-15, zeolite β and sulfonic acid functionalized hybrid silica—in solvent-free microwave-assisted synthesis of the corresponding coumarin derivatives has been investigated in detail. 7-Hydroxy-4-methylcoumarin and 4-methylcoumarin were obtained in 97% and 43% yields, respectively, over Amberlyst-15. This was the most active catalyst in the Pechmann reaction under studied conditions.

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“…16 Two plausible mechanisms have been proposed for the Pechmann condensation. The first was proposed by Robertson in 1932, 33 which is initiated by an electrophilic aromatic substitution followed by an intramolecular transesterification and a dehydration reaction. However, the order of the last two steps has not yet been identified.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of C4-substituted coumarins via Pechmann condensation catalyzed by sulfamic acid. Insights into the reaction mechanism by HRMS analysis

Barcellos¹,

Moraes²,

Lenardão³

2021

Arkivoc

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A series of functionalized C4-substituted coumarins were synthesized by exploring the reaction of activated and non-activated phenols and β-ketoesters under solvent-free conditions in the presence of sulfamic acid as a Br∅nsted acid catalyst. Fifteen examples were prepared with moderate to excellent yields (50% to 90%) using 10 mol % of the catalyst. Furthermore, it was possible from the proposed methodology to scale up the synthesis of coumarins to obtain up to 11 g of product. This work also provides a preliminary insight into the reaction mechanism using high-resolution mass spectrometry analysis. The key cinnamic acid derivative intermediate was detected, implying that under the evaluated conditions, the mechanistic pathway starts with an aromatic electrophilic substitution followed by dehydration reaction and intramolecular transesterification.

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223. Hydroxy-carbonyl compounds. Part VII. Coumarins and 1 : 4-benzopyrones derived from m-cresol

Cited by 24 publications

References 0 publications

The Chemistry of Coumarins.

The Chemistry of Coumarins.

Coumarin Derivatives Solvent-Free Synthesis under Microwave Irradiation over Heterogeneous Solid Catalysts

Synthesis of C4-substituted coumarins via Pechmann condensation catalyzed by sulfamic acid. Insights into the reaction mechanism by HRMS analysis

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