Cyrhetrenyl chalcones: Synthesis, characterization and antimalarial evaluation

Abstract A new series of hybrid organometallic-organic and dinuclear organometallic chalcones containing the cyrhetrenyl fragment were synthesised and characterised. 1 H and 13 C NMR spectra indicate that these compounds adopt in solution an E -stereochemistry at the C C bond, as well as the s - cis conformation of the enone moiety. A similar structure was also found for 1-ferrocenyl-3-cyrhetrenyl-2-propen-1-one ( 2i ) by X-ray crystallography in the solid state. The electron-withdrawing capability of the cyrhetrenyl group on the ketonic carbonyl and olefinic (C β ) carbons correlate properly with the 13 C shift of the carbon nuclei of the enone moiety. Evaluation of in vitro antimalarial activity of the compounds against the chloroquine-susceptible strain 3D7 and the chloroquine-resistant strain W2 of Plasmodium falciparum , indicates that these cyrhetrene conjugates are more active compared to their ferrocenic analogues.