The isomerization of 4-vinylcyclohexene catalyzed by Cp2TiCl2/Me2CHMgBr was studied. The system was found to have excellent catalytic activity and high selectivity. Thus, 4-vinylcyclohexene can be isomerized quant. into 3-ethylidenecyclohexene at 50 癈 in 2 h, and at 15 癈 for 2 h the main isomerization product was 4-ethylidenecyclohexene with 88% selectivity and 97% conversion. All the isomerization products were isolated and characterized by 1H NMR, MS and IR. The catalytic mechanism was discussed.

Key words: CATALYSIS, REACTION MECHANISM, CHLORIDE, CYCLOPENTADIENE P, ALKENE, ISOBUTYL GROUP, BROMOHYDROCARBON, METALLOCENES, TITANIUM COMPLEX, TRANSITION METAL COMPLEX