Cobalt-Catalysed Cyclotrimerisations: New Catalytic Systems, New Substrates and Products
Sprache des Vortragstitels:
XXIV Conference on Organometallic Chemistry
Sprache des Tagungstitel:
Group 9 metal complexes and especially cobalt complexes are frequently used catalysts for a large variety of cyclisation reactions, including the prominent Pauson-Khand reaction or [2+2+2] cycloaddition reactions. Our work is focussing on the latter, the cyclotrimerisation reaction, and deals with the develop of novel
CpCo(I)-complexes with olefin and phosphite ligands and their structure-reactivity relationships in cyclotrimerization reactions to construct benzenes and pyridines.The evaluation of these new precatalysts led to a great many of interesting insights and the implementation of the results in addition enabled the
development of new air-stable and recyclable CpCo(I) precatalysts for thermal as well as photochemical conditions. In the presentation also the synthesis and surprising catalytic capabilities of CpCo(III) precatalysts will be discussed.
We also investigate non-Cp-based cobalt catalyst systems and have found that cobalt complexes can be useful catalysts for asymmetric cyclisations as well as for the so far unknown Co-catalysed synthesis of functionalised phosphinines. In both cases the nature of the ligands as well as the oxidation state of the cobalt
is of significant importance and recent developments will be presented.