Oligomerization and simultaneous cyclization of ethylene to methylenecyclopentane catalyzed by zirconocene complexes

The oligomerization of ethylene catalyzed by Cp2ZrL2 (L=Cl, Me, OC6H4-Me-p) with ethylaluminoxane or Et3Al as cocatalyst (Al/Zr=100, 150°C, P(C2H4)=1.4 MPa) afforded not only common chain oligomers but also a cyclic oligomer, methylenecyclopentane. The selectivity of methylenecyclopentane reached 39% under optimal conditions. The addition of C5H5N to the catalytic system of Cp2ZrCl2/Et3Al was capable of further improving the selectivity of methylenecyclopentane to 43%.