In memory of Prof. Venkataraman: Recent advances in the synthetic methodologies of flavones

Kshatriya, Rajpratap; Jejurkar, Valmik P.; Saha, Satyajit

doi:10.1016/j.tet.2017.12.052

Cited by 55 publications

(37 citation statements)

References 142 publications

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“…To our delight, the corresponding flavones were formed in excellent yields (Scheme 6). Thus, the present strategy is also a suitable alternative to traditional flavone synthesis methods [17] …”

Section: Resultsmentioning

confidence: 94%

Metal‐Free, DBU‐Mediated, Microwave‐Assisted Synthesis of Benzo[c]xanthones by Tandem Reactions of Alkynyl‐1,3‐diketones

et al. 2020

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A base‐mediated, green, microwave‐assisted efficient preparation of a diverse benzoxanthone library from variety of readily accessible γ‐alkynyl 1,3‐diketones is reported. The synthesis is based on tandem reactions involving intramolecular cyclization, propargyl‐allenyl isomerization, and electrocyclization in one pot. Some of the benzoxanthones are also synthesized by the one‐pot reaction of 1,3‐diketone and alkynyl bromide under basic heating conditions. This transformation also results in the construction of one new C−C bond and one new C−O bond.

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Section: Resultsmentioning

confidence: 94%

Metal‐Free, DBU‐Mediated, Microwave‐Assisted Synthesis of Benzo[c]xanthones by Tandem Reactions of Alkynyl‐1,3‐diketones

et al. 2020

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“…Indeed, there is a legion of reports investigating the natural limitation of the aforementioned pathways, such as the use of abundant amounts of strong organic/inorganic acid/base, problematic isolation process, toxic transition metals with high catalyst loading, solvent-dependent reactions, and environment-dependent catalysts such as light, air and moisture. [5][6][7][8][9] Even under the most neoteric sets of conditions, archived and anecdotal evidence still exists that the synthesis of the benzopyran framework remains an enduring challenge in terms of conditions and substrates. Ionic liquids have received significant attention for their application as solvents/catalysts for organic transformation because of their unique physical and chemical properties.…”

Section: Introductionmentioning

confidence: 99%

Efficient synthesis of 4‐phenacylideneflavenes using recyclable gelified Brønsted acidic ionic liquid under solvent‐free and column chromatography‐free conditions: a green method and mechanistic insight

Nguyen

et al. 2021

J of Chemical Tech & Biotech

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BACKGROUND: Synthetic routes involving recyclable catalysts, solvent-free conditions and chromatography-free purification are becoming more popular as favorable substitutes for conventional ones. We report here the exciting possibility of producing selective functionalization of 4-phenacylideneflavenes using an efficient gelified Brønsted acidic ionic liquid (BAIL) as a recyclable catalyst from available and cheap starting materials.RESULTS: This one-pot cascade approach allowed the synthesis of various 4-phenacylideneflavenes in good yields with operational simplicity and easy workup. Moreover, the condensation of salicylaldehyde and acetophenone on a gram scale gave the desired product in 78% yield using our optimized conditions. In addition, the reaction mechanism in which two crucial intermediates were identified using high-resolution electrospray ionization mass spectrometry was also proposed in the present work.CONCLUSION: This method represents the first example of using BAIL gel recyclable catalyst in a straight and clean synthesis of various 4-phenacylideneflavenes from cheap and available starting materials, namely acetophenones and salicylaldehyde.

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“…Many approaches to the synthesis of flavones have been described. The most classical synthetic pathways involve either diaryl β‐diketones or chalcones as key intermediates, such as in the Baker–Venkataraman and Claisen–Schmidt rearrangements, respectively . However, no synthetic approach has been developed to access chalcone–flavone dimers.…”

Section: Introductionmentioning

confidence: 99%

First Total Synthesis of Original Chalcone–Flavone Dimers as Cissampeloflavone Analogues

2018

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The total synthesis of furoflavones closely related to the natural product cissampeloflavone was explored following different pathways. The involvement of a flavone as a key intermediate proved to be the most efficient way to form the 7‐phenyl‐5H‐furo[3,2‐g]chromen‐5‐one scaffold, and the first example of furoflavone formation was achieved in this way. For the synthesis of chalcone–flavone dimers, two different strategies were examined: either acylation at the very end of the synthesis, or introduction of the 3‐acyl group during furan‐ring formation. The final acylation was hardly achievable with hindered benzoyl chlorides, but a simpler 4‐methoxybenzoyl group was added to the furoflavone in modest yield. The alternative direct introduction of this acyl group during furan formation proved to be more efficient. Conjugate addition of an iodoflavone to an ynone followed by intramolecular Heck cyclization gave the best results, leading to the first synthetic chalcone–flavone dimer ever described.

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In memory of Prof. Venkataraman: Recent advances in the synthetic methodologies of flavones

Cited by 55 publications

References 142 publications

Metal‐Free, DBU‐Mediated, Microwave‐Assisted Synthesis of Benzo[c]xanthones by Tandem Reactions of Alkynyl‐1,3‐diketones

Metal‐Free, DBU‐Mediated, Microwave‐Assisted Synthesis of Benzo[c]xanthones by Tandem Reactions of Alkynyl‐1,3‐diketones

Efficient synthesis of 4‐phenacylideneflavenes using recyclable gelified Brønsted acidic ionic liquid under solvent‐free and column chromatography‐free conditions: a green method and mechanistic insight

First Total Synthesis of Original Chalcone–Flavone Dimers as Cissampeloflavone Analogues

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