Green synthesis of bis-(β-dicarbonyl)-methane derivatives and biological evaluation as putative anticandidial agents

Abstract

In this work the effectiveness of two different reaction media, an Ionic Liquid (IL) and a Deep Eutectic Solvent (DES), as greener, alternative solvents for the synthesis of bioactive bis-(β-dicarbonyl)-methane derivatives is examined. A domino Knoevenagel-Michael reaction between selected aromatic aldehydes and heterocyclic 1,3-dicarbonyl compounds was successfully accomplished, producing the desired compounds in satisfactory yields. The solvents were recycled and reused three times without noticeable decrease in reaction yields. A putative conformation of compound 4g was determined using NMR spectroscopy and an “anti” orientation of the fused aromatic rings was proposed. Moreover, some of the bis-(β-dicarbonyl)-methane derivatives were tested for their antifungal activity against four Candida albicans strains. Biscoumarin 6 and bisquinolinone 4d exhibited promising anticandidial activity. In parallel, in silico ligand-based similarity calculations provided a putative mechanism of action of the examined compounds through CYP51 inhibition.