Cyclopentadienyl-Based Anticancer Drugs: Improvement of Cytotoxic Activity through Functionalisation of the π Ligand

Dihydroguaiazulenide Complexes and Catalysts of Group 8-12 Transition Metals: Ligands from Renewable Feedstock Replace, even Outmatch Petrochemical Based Cyclopentadienyl Chemistry

We present an in-depth study of the sterically demanding Cp-synthon (8-H-GuaH)Li isolated from natural product guaiazulene (Gua) as a ligand transfer reagent towards late transition metal complex precursors. The synthesis and full characterization of selected, essentially unexplored homo- and heteroleptic 8-H-guaiazulenide complexes of iron, ruthenium, cobalt, rhodium, platinum, copper and zinc are discussed in detail. In order to demonstrate their potential in catalytic applications, [(GuaH)PtMe3 ] was selected. The latter proved an even higher catalytic activity in light induced olefin hydrosilylation at catalyst loads as low as 5 ppm than classical [CpPtMe3 ] in a typical test reaction of silicone elastomer fabrication. Our results demonstrate that traditional petrochemical based Cp metal chemistry and catalysis can be replaced, sometimes even outmatched by superior catalysts based on cheap building blocks from renewable feedstock.

Cyclopentadienyl Molybdenum(II) Compounds Bearing Ether and Thioether Functions in the Side Chain: Synthesis, Characterization, and Cytotoxic/Cytostatic Studies

A series of molybdenum(II) compounds [(η5 -Cp')Mo(CO)2 (L2 )][BF4 ] (Cp'=C5 H4 (CH2 )2 SPh, C9 H6 (CH2 )2 OMe, L2= N,N-chelating ligand) have been synthesized and characterized by spectroscopic and analytical methods including X-ray crystallography. The in vitro assay on human leukemia cells MOLT-4 has shown that the substitution in the π-ligand in combination with suitable N,N-chelating ligand can lead to species with cytotoxicity considerably higher than reported to cisplatin. Unusually high activity was observed for compounds bearing phenanthroline ligands [{η5 -C9 H6 (CH2 )2 OMe}Mo(CO)2 (3,4,7,8-Me4 phen)][BF4 ] (IC50 =0.7±0.3 μM) and [{η5 -C9 H6 (CH2 )2 OMe}Mo(CO)2 (4,7-Ph2 phen)][BF4 ] (IC50 values 0.8±0.4 μM).