A Convergent Total Synthesis of the Biologically Active Benzo­furans Ailanthoidol, Egonol and Homoegonol from Biomass-Derived­ Eugenol

A rapid, and metal‐free approach for the synthesis of functionalized benzofurans 10 is illustrated by PhI 9 catalyzed cyclization of 2‐hydroxystilbenes 8. The 2‐hydroxystilbenes 8 were cyclized using 10 mol % PhI as a precatalyst, 2.0 equiv. of m‐CPBA as an oxidant and 2.4 equiv. of TFA as an additive at room temperature under ultrasonic irradiation condition. The functionalized benzofurans 10 were gained in good to excellent yields with shorter reaction times.

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Ultrasonic‐Assisted Hypervalent Iodine‐Catalyzed Cyclization of (E)‐2‐Hydroxystilbenes to Benzofurans Using Iodobenzene as Pre‐catalyst

Mangaonkar¹,

Shetgaonkar²,

Vernekar

et al. 2020

ChemistrySelect

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Synthesis of Bromo Eugenol Derivatives with Molecular Bromine

Putri,

Sugita,

Arifin

2024

J. Kim. Sains Apl.

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The bromination of eugenol using molecular bromine (Br2) has been widely reported. However, the outcomes have been inconsistent, and as a result, the specific steps of the bromination process have not been definitively established. This research aims to synthesize various derivatives of bromo eugenol, incorporating bromine atoms either in the alkene group, the aromatic ring, or both. The synthetic approaches employed include: (1) direct bromination of eugenol using 1.2, 2.4, and 3.6 equivalents (equiv) of Br2 in chloroform, (2) bromination of eugenyl benzoate with 2.4 equiv of Br2 in chloroform, and (3) debromination of the 1,2-dibromide functionality in selected bromination products using an excess of zinc in ethanol. The bromination steps of eugenol were then proposed based on the composition of the products obtained. Alkene bromination of eugenol predominated with 1.2 equiv of Br2, followed by aromatic bromination with excess Br2 (2.4 and 3.6 equiv). Aromatic substitution primarily occurred at position 6 (ortho to the hydroxyl group) and subsequently at position 5 (para to the methoxy group). Based on these results, we propose that the bromination of eugenol with Br2 proceeds initially through electrophilic addition to the alkene group, followed by electrophilic substitution on the aromatic ring. Protection of the phenol as a benzoyl ester shifted the regioselectivity of the first aromatic bromination from position 6 to 5. Furthermore, the 1,2-dibromide group has been successfully removed by zinc, resulting in derivatives containing bromine atoms only at the aromatic ring. This is by far the first comprehensive report on the bromination of eugenol with Br2 and the first one reporting the bromination of alkene as the main route of bromination with a nearly equimolar amount of Br2.

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Tailored Functionalization of Natural Phenols to Improve Biological Activity

et al. 2021

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Phenols are widespread in nature, being the major components of several plants and essential oils. Natural phenols’ anti-microbial, anti-bacterial, anti-oxidant, pharmacological and nutritional properties are, nowadays, well established. Hence, given their peculiar biological role, numerous studies are currently ongoing to overcome their limitations, as well as to enhance their activity. In this review, the functionalization of selected natural phenols is critically examined, mainly highlighting their improved bioactivity after the proper chemical transformations. In particular, functionalization of the most abundant naturally occurring monophenols, diphenols, lipidic phenols, phenolic acids, polyphenols and curcumin derivatives is explored.

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A Convergent Total Synthesis of the Biologically Active Benzofurans Ailanthoidol, Egonol and Homoegonol from Biomass-Derived Eugenol

Cited by 3 publications

References 21 publications

Ultrasonic‐Assisted Hypervalent Iodine‐Catalyzed Cyclization of (E)‐2‐Hydroxystilbenes to Benzofurans Using Iodobenzene as Pre‐catalyst

Ultrasonic‐Assisted Hypervalent Iodine‐Catalyzed Cyclization of (E)‐2‐Hydroxystilbenes to Benzofurans Using Iodobenzene as Pre‐catalyst

Synthesis of Bromo Eugenol Derivatives with Molecular Bromine

Tailored Functionalization of Natural Phenols to Improve Biological Activity

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A Convergent Total Synthesis of the Biologically Active Benzo­furans Ailanthoidol, Egonol and Homoegonol from Biomass-Derived­ Eugenol

Cited by 3 publications

References 21 publications

Ultrasonic‐Assisted Hypervalent Iodine‐Catalyzed Cyclization of (E)‐2‐Hydroxystilbenes to Benzofurans Using Iodobenzene as Pre‐catalyst

Ultrasonic‐Assisted Hypervalent Iodine‐Catalyzed Cyclization of (E)‐2‐Hydroxystilbenes to Benzofurans Using Iodobenzene as Pre‐catalyst

Synthesis of Bromo Eugenol Derivatives with Molecular Bromine

Tailored Functionalization of Natural Phenols to Improve Biological Activity

Contact Info

Product

Resources

About

A Convergent Total Synthesis of the Biologically Active Benzofurans Ailanthoidol, Egonol and Homoegonol from Biomass-Derived Eugenol