Halogenated Flavones and Isoflavones: A State-of-Art Study on their Synthesis

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Author(s): Ricardo A. L. S. Santos, Diana C. G. A. Pinto, M. Clara F. Magalhães, Artur M. S. Silva*

Journal Name: Current Organic Synthesis

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Abstract:

Background: Flavonoid is a family of compounds present in the everyday consumption plants and fruits, contributing to a balanced diet and having health effects. Being a scaffold for new drugs and presenting a wide range of applicability in illness treatment gives them also an impact in medicine. Among the several types of flavonoids, flavone and isoflavone derivatives can be highlighted due to their prevalence in nature and biological activities already established. The standard synthetic route to obtain both halogenated flavones and isoflavones is through the use of already halogenated starting materials. Halogenation of the flavone and isoflavone core is less common because it is more complicated and involves some selectivity issues.

Objective: Considering the importance of these flavonoids, we aim to present the main and more recent synthetic approaches towards their halogenation.

Methods: The most prominent methodologies for the synthesis of halogenated flavones and isoflavones were reviewed. A careful survey of the reported data, using mainly the Scopus database and halogenation, flavones and isoflavones as keywords, was done.

Results: Herein, a review has been taken from the latest and more efficient halogenation protocols of flavones and isoflavones previously built cores. Selective halogenation and the greener methodologies, including enzymatic and microbial halogenations, were reported. Nevertheless, some interesting protocols that allowed the synthesis of halogenated flavone and isoflavone derivatives in specific positions using halogenated reagents were also summarized.

Conclusion: Halogenated flavones and isoflavones have risen as noticeable structures; however, most of the time, the synthetic procedures involve toxic reagents and harsh reaction conditions. Therefore, the development of new synthetic routes with low environmental impact is desirable.

Keywords: Flavonoids, selective halogenation, enzymatic halogenation, microbial halogenation, substitution reactions, addition reactions, flavones, isoflavones

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Article Details

(E-pub Ahead of Print)
DOI: 10.2174/1570179417666200530213737
Price: $95

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