Synthesis of Unsymmetrically 1,3,5-Trisubstituted Arenes via Site-Selective Sequential Silylation and Borylation.

A catalytic, site-selective silylation and borylation sequence allows the synthesis of unsymmetrically 1,3,5-trisubstituted arenes. A spirobipyridine ligand bearing a "steric roof", in combination with iridium creates a catalyst that recognizes the shape of a monosubstituted arene, to enable the selective reaction of a variety of substrates, regardless of their electronic properties. Both silylation followed by borylation and borylation followed by silylation are demonstrated. The resulting compounds bearing a boron and a silicon handle can be used as a modular gateway to 1,3,5-trisubstituted arenes, as demonstrated by an orthogonal arylation/alkylation protocol.