Selective Access to Silacyclopentanes and Homoallylsilanes by La-Catalyzed Hydrosilylations of 1-Aryl Methylenecyclopropanes
Xiaoming Xu, Xiaoming Xu, Ailin Gao, Xiufang Xu, Xiufang Xu, Jianfeng Li, Chunming Cui
Abstract
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.