Preparation of 1,1′-binaphthyl-2,2′-diyl bridged ansa-bis( annulated cyclopentadienyl) titanium and -zirconium dichloride complexes

Article abstract of DOI:10.1016/S0022-328X(96)06635-1

The coupling of enantiomerically enriched 2,2′-dilithio-1,1′-binaphthyl with various annulated cyclopentenones or 2-indanone proves to be a facile route for the preparation of a series of annulated bis(cyclopentadienes) or bis(indenes) bridged at a symmetrical cyclopentadienyl position. The six-or seven-membered annulated bis(tetrahydroindene) 6 or bis(hexahydroazulene) 7 ligands could readily be converted to titanium or zirconium dichloride complexes. Owing to the symmetry of the ligands, only a single C₂-symmetrical isomer of the metallocene dichloride could form. Although the faces of the cyclopentadienyl moieties are homotopic, the chiral bridge enforces a chiral conformation of the metallocene complexes. The bis(indenyl) 5 or five-membered annulated bis(tetrahydropentalene) 8 ligands could not be metalated. Unbridged 2-methyl and 2-phenyl substituted tetrahydropentalenes 27 and 28 were prepared and could readily be converted to titanium dichloride complexes.