Zeolite-catalyzed synthesis of 2,3-unsubstituted benzo[b]furans via the intramolecular cyclization of 2-aryloxyacetaldehyde acetals

Sun, Nan; Huang, Peng; Wang, Yifan; Mo, Weimin; Hu, Baoxiang; Shen, Zhenlu; Hu, Xinquan

doi:10.1016/j.tet.2015.05.029

Cited by 16 publications

(4 citation statements)

References 42 publications

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“…The synthesis methods are given in the Supporting Information (Method S1). Because the α-position of furan can easily be halogenated, the key intermediate is 6-bromobenzofuran, which was prepared according to the literature. , Although a trace amount of 4-bromobenzofuran was also formed as an inseparable side product and the mixture of isomers was used for the next reaction, the final products can be isolated in pure form. As a result, BPBFCz1 and BPBFCz2 were successfully synthesized in relatively high yields in five steps.…”

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confidence: 99%

Design Strategy for Robust Organic Semiconductor Laser Dyes

Oyama

Mamada

Shukla

et al. 2020

ACS Materials Lett.

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A new molecular design for organic semiconductor laser dyes showing excellent optical properties and high robustness is disclosed in this work. The suitability of a furan moiety for increasing the thermal and photostability in newly developed furan-based derivatives (BPBFCz) is demonstrated by comparing a well-known laser molecule (BSBCz) having a bis-stilbene unit. The new derivatives exhibited high photoluminescence quantum yields of nearly 100% and radiative rate constants of ∼10 9 s −1 in both solution and doped films, and their properties were also excellent in neat films. The amplified spontaneous emission (ASE) thresholds of the BPBFCz materials were found to be very low (<1 μJ cm −2 ), and the excited-state absorption in the ASE oscillation region was negligible, which is preferable for laser applications. In addition to these excellent optical properties, which are comparable or superior to those of BSBCz, the decomposition temperatures of the BPBFCz emitters were much higher than that of BSBCz, resulting in the suppression of impurity formation during the thermal deposition. In addition, the photostability of the new materials was dramatically improved compared with that of BSBCz. This study serves as a very significant advancement toward the practical application of organic semiconductor laser diodes and provides molecular design guidelines for robust organic laser molecules.

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confidence: 99%

Design Strategy for Robust Organic Semiconductor Laser Dyes

Oyama

Mamada

Shukla

et al. 2020

ACS Materials Lett.

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“…We planned to build the substituted benzo[b]furan 19 from 9 by creating the annellated 2,3-unsubstituted furan ring according to our previously sound synthetic pathway B for target compound 1 ( Scheme 2 ). Thus, once etherified the phenolic group of 9 with the functionalized two carbon fragment, the resulting compound 18 was cyclized to 19 under the action of PPA (Sn-β zeolite also showed to efficiently promote this transformation [ 48 ]). As expected, we found the subsequent electrophilic aromatic substitution reaction was poorly regioselective: all but one of the regioisomeric formyl benzofuran derivatives 2-FBF , 5-FBF , and 6-FBF were formed.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and NLRP3-Inflammasome Inhibitory Activity of the Naturally Occurring Velutone F and of Its Non-Natural Regioisomeric Chalconoids

Ventura

Perrone

Missiroli

et al. 2022

IJMS

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Plant-derived remedies rich in chalcone-based compounds have been known for centuries in the treatment of specific diseases, and nowadays, the fascinating chalcone framework is considered a useful and, above all, abundant natural chemotype. Velutone F, a new chalconoid from Millettia velutina, exhibits a potent effect as an NLRP3-inflammasome inhibitor; the search for new natural/non-natural lead compounds as NLRP3 inhibitors is a current topical subject in medicinal chemistry. The details of our work toward the synthesis of velutone F and the unknown non-natural regioisomers are herein reported. We used different synthetic strategies both for the construction of the distinctive benzofuran nucleus (BF) and for the key phenylpropenone system (PhP). Importantly, we have disclosed a facile entry to the velutone F via synthetic routes that can also be useful for preparing non-natural analogs, a prerequisite for extensive SAR studies on the new flavonoid class of NLRP3-inhibitors.

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“…For example, a 2,3-unsubstituted benzofuran can be obtained from 2,2-diethoxyethoxybenzene in the presence of a Brønsted or Lewis acid via acetal deprotection, intramolecular Friedel–Crafts reaction, and the following dehydration. Some acids, including polyphosphoric acid (PPA), Amberlyst-15, H 3 PO 4 , and Sn-β zeolite, promote the transformations (Scheme ). These acids allow for rapid and linear construction of benzofuran rings, but some problems exist: PPA is highly viscous, making workup difficult and generating large amounts of water-soluble waste, and Amberlyst-15 has weaker mechanical strength under high-temperature conditions.…”

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confidence: 99%

Scandium-Catalyzed Phenol-Directed Construction of 5-Carbonyl-4-hydroxybenzofurans via Intramolecular Friedel–Crafts Reaction

Kuribara,

Kaneki,

Mihara

et al. 2023

Org. Lett.

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Herein we report a scandium-catalyzed regioselective synthesis of 5-carbonyl-4-hydroxybenzofurans via a phenol-directed intramolecular Friedel−Crafts reaction. This synthetic method was applied for the total synthesis of furanoflavones. Experimental studies and density functional theory calculations suggest that hydrogen bond interactions between the phenolic hydroxy group and the scandium complex realize regioselective intramolecular cyclization.

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Zeolite-catalyzed synthesis of 2,3-unsubstituted benzo[b]furans via the intramolecular cyclization of 2-aryloxyacetaldehyde acetals

Cited by 16 publications

References 42 publications

Design Strategy for Robust Organic Semiconductor Laser Dyes

Design Strategy for Robust Organic Semiconductor Laser Dyes

Synthesis and NLRP3-Inflammasome Inhibitory Activity of the Naturally Occurring Velutone F and of Its Non-Natural Regioisomeric Chalconoids

Scandium-Catalyzed Phenol-Directed Construction of 5-Carbonyl-4-hydroxybenzofurans via Intramolecular Friedel–Crafts Reaction

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