Design of a new synthetic pathway to tetrahydroindenyl ligands for organotransition metal catalysts"

The most widely used approach to tetrahydroindenyl ligands involves the synthesis of the corresponding indenyl organometallic complexes followed by catalytic hydrogenation. Although very efficient, this approach does not allow a wide range of structural modifications in the basic molecule, thus setting limitations to a fine "tuning" of the stereochemical characteristics of the catalyst. Furthermore, the hydrogenation step often proceeds in modest yields and the high pressures of hydrogen sometimes required can present explosion hazards. Here we report a new general method3 for the synthesis of fused cyclopentadienyl bicyclic systems, capable to lead to the desired organometallic compounds with good yields, in a big scale, if necessary, and with an easily reproducible synthetic pathway. With this method it is also possible to synthetise the corresponding ansa-bridged tetrahydroindenyl complexes, well known homogeneous olefin polymerisation (Ziegler-Natta type) catalysts.