Mannose‐Inspired Mesoionic Carbenes: Building Antitumor Palladium(II) Allyl Complexes

The synthesis and anticancer evaluation of palladium(II) com-plexes bearing mannose-conjugated mesoionic carbenes andtheir triazolium precursors (triazolium palladates) is reported.Ligand precursors are easily obtained via copper-catalyzedazide–alkyne cycloaddition. Palladium allyl carbene complexesare prepared extending the weak base route protocol to triazo-lium salts by reacting the metal precursor and azolium salts withpotassium carbonate as the base in acetonitrile and under mildconditions. Additionally, triazolium allyl palladates are isolated,which represent the first examples of triazolium palladate com-plexes described in the literature. In vitro tests on a panel of can-cer cell lines (A2780, A2780cis, DLD-1) reveal better or comparablecytotoxicity to cisplatin. The majority of complexes exhibit lowcytotoxicity (>100 μM) toward MRC-5 and FT-190 nontumoral celllines demonstrating remarkable in vitro selectivity.