Chalcone: A Valuable Scaffold Upgrading by Green Methods

Chalcones are naturally occurring α,β-unsaturated carbonyl compounds owning a wide range of pharmaceutical and industrial applications. They are also key precursors in the biosynthesis of other flavonoids and in the synthesis of many biologically valuable heterocyclic compounds (e.g., benzothiazepines, pyrazolines and flavones). These facts stimulate vast interest in their synthesis and transformation among organic and medicinal chemists. Because of the increasing attention to environmental pollution in our society, the application of eco-friendly synthetic methods is starting to be chemists’ first choice. This review unveils the green methods employed in the transformation of chalcones focusing on biocatalysis, though the use of other so-called green strategies will be mentioned as well. The versatility, efficiency and reactional conditions as well as the advantages and disadvantages of these approaches will be disclosed. Interesting results such as the fact that biocatalysis with microorganisms leads to flavones, whereas with enzymes leads to dihydrochalcones or that microwave and ultrasound irradiation minimize environmental effects, will be discussed. The applied research will unveil the knowledge gaps and eventually guide future researchers.