Cyclopropanation on a highly active heterogeneous catalyst: (Formula presented)

Some heterogeneous catalysts, cupric oxide supported on different supports, were prepared and employed to catalyze the cyclopropanation of styrene and 2,5-dimethyl-2,4-hexadiene with ethyl diazoacetate (EDA). The catalytic performance for cyclopropanation strongly depends on the nature of the support. A novel catalyst, CuO/TiO₂-Al₂O₃, in which Al₂O₃ is modified with a monolayer TiO₂, is found to be most active and selective for the cyclopropanation reaction. The yields of 93 and 94% cyclopropanes are obtained for styrene and 2,5-dimethyl-2,4-hexadiene at 40 °C as the substrates, respectively. The activity and selectivity in cyclopropanes are optimized with a monolayer dispersion of cupric oxide on the corresponding supports.