Simple and efficient synthesis of benzofuran derivatives from tyrosol

Paolo Bovicelli,Fabrizio Bottaro,Carla Sappino,Michela Tomei,Valentina Nardi,Ilaria Proietti Silvestri,Beatrice Macchi,Caterina Frezza,Giuliana Righi

doi:10.1080/00397911.2015.1133828

Paolo Bovicelli, Fabrizio Bottaro + Show 7 more

Open Access

https://doi.org/10.1080/00397911.2015.1133828

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Abstract

ABSTRACTA convenient strategy for the preparation of compounds bearing the benzofuran skeleton starting from tyrosol, a phenol largely present in olive oil production waste, with no biological importance, is reported. A bromination/methoxylation sequence, already described for the synthetic transformation of naturally occurring compounds, was exploited. Depending on the solvent used for the methoxylation reaction together with the presence of a 4-phenol moiety respect to the side chain, benzodihydrofurans or a benzofurans derivative can be obtained.

Highlights

In the last years we have largely investigated a method to oxyfunctionalize the aromatic ring of natural occurring compounds in order to enhance their biological activities.[1]
The bromination of activated aromatic rings can be performed by a number of methods,[3] but we found the system NaBr/Oxone to be the most efficient and clean
In this work we describe a facile and straightforward synthesis of benzofuran derivatives starting from tyrosol using the bromination/methoxylation approach

Summary

Introduction

In the last years we have largely investigated a method to oxyfunctionalize the aromatic ring of natural occurring compounds in order to enhance their biological activities.[1] The method involves a methoxylation of an aromatic bromide, a reaction optimized by us and already reported.[2] The bromination of activated aromatic rings can be performed by a number of methods,[3] but we found the system NaBr/Oxone to be the most efficient and clean. The most interesting example is the bromination of tyrosol (4-hydroxyphenethyl alcohol) which can be selectively transformed to the monobromo or dibromo derivatives, allowing to access to aromatic compounds with different degree of oxygenation. The main example of the potentiality of this synthetic pathway for the preparation of compounds bearing the benzofuran skeleton is the and convenient transformation of tyrosol into hydroxytyrosol.[4]

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