Revealing Silylation of C(sp2 )/C(sp3 )-H Bonds in Arylphosphines by Ruthenium Catalysis.

The first aromatic C-H silylation between arylphosphines and hydrosilanes enabled by a ruthenium complex has been developed. The excellent ortho-selectivity results from a four-membered metallacyclic intermediate involving phosphorus chelation. The developed system can be extended to the benzylic C-H silylation of arylphosphines. Diverse silylated arylphosphines are produced, exhibiting broad functional group compatibility. Further functionalization of the products under mild conditions renders the formed compounds useful building blocks.