Selenium-Directed ortho-C-H Borylation by Iridium Catalysis

An iridium-catalyzed selenium-directed ortho-C-H borylation of benzyl selenide derivatives was successfully developed. This is the first example where selenium is used as a directing group in C-H borylation. The reaction was carried out using the tricyclohexylphosphine ligand for an improved catalytic efficiency. Various substrates were tolerated and afforded either ortho-monoborylated products (substrates bearing ortho- or meta-substituents) or diborylated products (substrates bearing parasubstituents) in good yields. This study provides an efficient synthetic method for the preparation of a variety of organo-selenium compounds.