Recent advances in the synthesis of 4H-chromen-4-ones (2012 − 2021)

Santos, Clementina M.M.; Silva, Artur M. S.

doi:10.1016/bs.aihch.2022.02.001

Cited by 4 publications

(2 citation statements)

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“…The synthesis of flavonoid compounds has fascinated chemists for many decades, this is due to their rich and diverse chemistry, and their medicinal and photochemical properties [1][2][3]. Flavonoids, are a class of polyphenols obtained through secondary metabolism pathways, that are present in our diet and possess multiple biological activities [4].…”

Section: Introductionmentioning

confidence: 99%

Revisiting the Algar-Flynn-Oyamada (AFO) Reaction Mechanism: Computational and other Studies

Teixeira,

Sousa,

Burke

2024

Preprint

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The flavonoid family is a diverse family of natural phenolic compounds, with multiple biological properties. Both flavonols and aurones and their derivatives are key flavonoid compounds. These molecules traditionally have been obtained through the classical Algar, Flynn and Oyamada (AFO) reaction by treatment of 2’-hydroxychalcones with alkaline hydrogen peroxide. The mechanism is controversial, with indications of the formation of an epoxide intermediate when there is a substituent in the 6’-position (giving aurones and other benzofuran-2-one derivatives), and in the case of the 6’-substituted substratesan oxidative cyclization (directly or step-wise) involving no epoxide intermediates to give flavanols (Dean and Podimuang mechanism). In this paper, the mechanism of this reaction was studied computationally (DFT calculations) and the results indicated that for the unsubstituted systems the Dean and Podimuang mechanism is favoured both kinetically and thermodynamically, but in the case of the substituted systems, although the former mechanism is again favoured kinetically, both mechanisms show similar energies at the thermodynamic level, indicating that both the Dean and Podimuang mechanism and the epoxide forming pathway may operate in parallel. Interestingly, the calculations indicated an unexpected electrophilic hydroperoxide epoxidation route instead of a nucleophilic epoxidation route. Modified AFO conditions were studied whereby H2O2 was replaced by mCPBA, these experiments afforded mainly flavanone and some AFO products in low yields.

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Section: Introductionmentioning

confidence: 99%

Revisiting the Algar-Flynn-Oyamada (AFO) Reaction Mechanism: Computational and other Studies

Teixeira,

Sousa,

Burke

2024

Preprint

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“…3 In general, acylation is achieved by the reaction of alcohols with anhydrides due to the ease of deprotection. 4,5 Several different catalysts developed for the activation of anhydrides include nucleophilic agents such as 4-dimethylaminopyridine (DMAP) 6 and Bu 3 P, 7 and Lewis acids such as CoCl 2 , [7][8][9] as well as diverse triflates Sc(OTf) 2 , 10 Ce(OTf) 2 , 11 Pd(PhCN) 2 (OTf), 12 TMSOTf, 13 In (OTf) 2 , 14 Bi(OTf) 3 , 15,16 Cu(OTf) 2 17,18 and Cu(CH 3 CN) 4 OTf, 19 TaCl 5 , 20 zeolites, 21 clays, 22 Nafion-H, 23 yttria-zirconia, 24 LiClO 4 25 and ion liquids. 26 However, these catalysts suffer from various limitations.…”

Section: Introductionmentioning

confidence: 99%

Novel base‐catalyzed acylation of benzenediols with vinyl acetate: a Hirshfeld surface study

Ali,

Isaev,

Chichigina

et al. 2024

J of Chemical Tech & Biotech

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BACKGROUNDThe present work describes the facile, fast and economic base‐catalyzed acylation of benzenediols with vinyl acetate. The Hirshfeld surface analysis of benzene‐1,4‐diol O,O′‐diacetate is also described. NaOH, KOH and K2CO3 were the bases used for the catalysis of the acylation of benzene‐1,x‐diols (x = 2, 3, 4) with vinyl acetate to obtain the corresponding O,O′‐diacetyl derivatives.RESULTSThe yields were quite good, up to 99% under solvent‐free conditions. This method represents an alternative ‘green’ process for the preparation of O‐acetyl derivatives of hydroxyaryls. The benzene‐1,4‐diol O,O′‐diacetate crystal structure was obtained and described using Hirshfeld surface analysis. A noticeable contribution of the C⋯H contacts is shown (16.7%), despite the insignificant area of the Hirshfeld surface occupied by the carbon atoms (9.4%). By using two‐dimensional fingerprint plots, it was proved that C⋯H contacts were due to the presence of π‐stacking. The O⋯H contacts (41.4%) were the most numerous ones, relating mainly to typical hydrogen bonds (de + di ≈ 2.6 Å). The high saturation of the C⋯H and O⋯H contacts (enrichment ratios (E) = 1.30 and 1.36, respectively), despite their smaller contribution to the overall surface as compared to the H⋯H contacts (E = 0.84), is shown.CONCLUSIONThe novelty of this work is the development of a method based on an inexpensive, safe and easy‐to‐use catalyst (K2CO3). This method is fast with high yields. Besides, it may be used for acylation at an industrial scale. © 2024 Society of Chemical Industry (SCI).

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tert‐Butyl Hydroperoxide (TBHP): Recent Progress in C−H Functionalization and Heteroatom‐Heteroatom Bond Formations

Varala,

Seema,

Hussein

et al. 2024

ChemistrySelect

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Abstracttert‐Butyl hydroperoxide (tBuOOH, TBHP) is a commonly used hydroperoxide in many oxidation processes. The primary factors contributing to the increasing usefulness of TBHP include its affordability, eco‐friendliness, exceptional efficacy, and capacity to substitute harmful or rare heavy metal oxidants. In this sexennial update, we thoroughly and critically examined the most noteworthy applications of TBHP in C−H functionalization and heteroatom‐heteroatom bond formation reactions from 2018 till the present. The review has been subdivided based on the nature of the bonds being formed. The review focuses on the advantages and disadvantages of using synthetic organic transformations, as well as the breadth of their use and the underlying mechanisms involved.

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Recent advances in the synthesis of 4H-chromen-4-ones (2012 − 2021)

Cited by 4 publications

References 427 publications

Revisiting the Algar-Flynn-Oyamada (AFO) Reaction Mechanism: Computational and other Studies

Revisiting the Algar-Flynn-Oyamada (AFO) Reaction Mechanism: Computational and other Studies

Novel base‐catalyzed acylation of benzenediols with vinyl acetate: a Hirshfeld surface study

tert‐Butyl Hydroperoxide (TBHP): Recent Progress in C−H Functionalization and Heteroatom‐Heteroatom Bond Formations

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