Abstract
Although the directing group assisted ortho-B − H activation reactions of o-carboranes have been well established during the past decade, the meta-B − H activation reactions are unexplored so far. Herein, iridium(III)-catalyzed remote B(9) − H alkylation reactions of o-carboranes with nitrile template have been demonstrated for the first time. It was revealed that fine tuning of the template structures is essential for high reaction efficiency and regioselectivity. This alkylation process exhibits a broad substrate scope with good functional group tolerance under simple reaction conditions. The nitrile template, readily accessible from o-carborane acids, can be removed conveniently after completion of the reaction. The present method provides a powerful synthetic route to complex o-carborane derivatives, demonstrating successful larger scale alkylation and further molecular transformations of the B(9)-alkylated products.