Selective Access to Silacyclopentanes and Homoallylsilanes by La-Catalyzed Hydrosilylations of 1-Aryl Methylenecyclopropanes.

Methylenecyclopropanes (MCPs) have emerged as versatile building blocks in synthetic chemistry because of their unique reactivity. However, metal-catalyzed hydrosilylation of MCPs has met with very limited successes. In this paper, catalytic selective hydrosilylations of MCPs with some primary silanes using an ene-diamido lanthanum ate complex as the catalyst were described. The catalytic reactions resulted in the selective formation of silacyclopentanes and ( E )-homoallylsilanes, respectively, depending on the substituents on MCPs. The formation of silacyclopentanes via a catalytic cascade inter- and intramolecular hydrosilylation mechanism is strongly supported by the control and deuteration-labeling experiments and DFT calculations. The unique reactivity and selectivity could be attributed to the large lanthanum ion and ate structure of the catalyst.