Trifluoromethylpyridine-Substituted N-Heterocyclic Carbenes Related to Natural Products: Synthesis, Structure, and Potential Antitumor Activity of some Corresponding Gold(I), Rhodium(I), and Iridium(I) Complexes

This work presents the synthesis, characterization, and application of several new metal(I) complexes with trifluoromethylpyridine‐containing N‐heterocyclic carbene (NHC) ligands. The metal of choice was gold(I) for compounds 7 – 10, rhodium(I) for 11 – 12, and iridium(I) for 13 – 14, respectively. The trifluoromethylpyridine moiety was incorporated, along with other biologically active moieties, with the intention of modifying the lipophilicity of the complexes, so that the transport of the active units (M–NHC) through the cell wall barrier is facilitated. The biological activity of the complexes was investigated. In vitro assessment of antitumor activity in a panel of 12 human tumor cell lines by a monolayer assay revealed good potency (mean IC50 12.6 μm) and tumor selectivity for one compound. The solid‐state structures of two solvates of compound 7, one with MeOH and one with THF, were determined by X‐ray diffraction analysis.