Encapsulation of Hoveyda-Grubbs2nd Catalyst within Yolk-Shell Structured Silica for Olefin Metathesis

Through postreducing the pore size of a mesoporous shell, Hoveyd-Grubbs(2nd) catalyst was successfully encapsulated within yolk shell structured silica, leading to a heterogeneous catalyst for olefin metathesis. Such a catalyst exhibits much higher activity than the reported encapsulated catalysts in olefin ring-closing metathesis and cross metathesis. This excellent activity can be attributed to the combination of a hollow structure in the interior and permeable mesopores in the shells. This catalyst shows good recyclability, highlighted by eight cycles of reaction. This work not only supplies an excellent heterogeneous olefin metathesis catalyst but also demonstrates that yolk-shell structured silica materials can be used as an innovative scaffold to encapsulate homogeneous catalysts.