Titanium‐Catalyzed C─X and C─H Borylation of Aryl Halides for the Synthesis of Bis(boronate)benzenes

Despite the intensive studies on the synthesis and application of aryl boronates, most focus on mono‐borylated arenes. The multi‐borylated arenes, on the other hand, have received much less attention because the preparation of multi‐borylated arenes in a straightforward manner is still underdeveloped. Herein, we present our findings on synthesizing bis‐borylated arenes from structure‐diverse and readily available aryl halides (Ar─X, X = Cl, Br, I). Simultaneous C─X and C─H borylation of aryl halides is achieved using earth‐abundant titanium as a catalyst. Not only the 1,2‐bis borylation but also the 1,3‐ and 1,4‐bis borylation are achieved. Control experiments and density functional theory (DFT) computations propose a titanium‐mediated aryl radical‐driven reaction resulting in selective bis‐borylation over mono‐borylation.