An efficient synthetic method of ansa-zirconocene dimethyl complexes via Me2ZrCl2

Abstract

The reaction of ZrCl4 with 2 equiv. of MeLi to form Me2ZrCl2 followed, by in situ metalation of Me2ZrCl2 with the corresponding ansa-ligands produces the respective ansa-dimethylzirconocene complexes, o-Xyl(Ind)(2)ZrMe2 [1b, Ind=eta(5)-1-indenyl, o-Xyl=C6H4(CH3)(2)-1,2], 2-Bn(Ind)(2)ZrMe2 [2b, 2-Bu=(-CH2CH=CHCH2-)], Et(Ind)(2)ZrMe2 (3b), and Me2Si(Znd)(2)ZrMe2 (4b) in high yields. Treatment of 1b-3b with HCl affords ansa-dichlorozirconocene complexes, 1a-3a, in quantitative yields. Synthesis of ansa-dimethylzirconocene via Me2ZrCl2 is more efficient than that via Cp2ZrCl2 (Cp-2=ansa-ligand) in the conventional methods. (C) 1997 Elsevier Science S.A.