Thermally Stable Dialkylzirconocenes with β-Hydrogens. Synthesis and Diastereoselectivity
摘要:
Alkylation Of (CP2ZrCl2)-Zr-r (Cp-r = Cp (eta (5)-C5H5), Cp '(eta (5)-C5H4Me), Cp* (eta (5)-C5Me5)) and CpCp*Zr(CH3)Cl with 1-lithio-2-methylpentane ((RLi)-Li-1) gives the corresponding dialkylzirconocenes (Cp2ZrR21)-Zr-r and CpCp*Zr(CH3)R-1, in high yields. Such alkyls have unprecedented thermal stabilities, especially for the CpCp* ligand framework. The diastereomers of the (Cp2ZrR21)-Zr-r complexes are formed in a statistical distribution, whereas the diastereomers of CpCp*Zr(CH3)R-1 form in a 2:3 ratio.