Boryl-Directed, Ir-Catalyzed C(sp³)–H Borylation of Alkylboronic Acids Leading to Site-Selective Synthesis of Polyborylalkanes

Pyrazolylaniline serves as a temporary directing group attached to the boron atom of alkylboronic acids in Ir-catalyzed C­(sp³)–H borylation. The reaction takes place at α-, β-, and γ-C–H bonds, giving polyborylated products including di-, tri-, tetra-, and even pentaborylalkanes. α-C–H borylation was generally found to be the preferred reaction of primary alkylboronic acid derivatives, whereas β- or γ-borylation also occurred if β- or γ-C–H bonds were located on the methyl group.