Rh‐Catalyzed Decarbonylative Cross‐Coupling between o‐Carboranes and Twisted Amides: A Regioselective, Additive‐Free, and Concise Late‐Stage Carboranylation

The convenient cross‐coupling of sp2 or sp3 carbons with a specific boron vertex on carborane cage represents significant synthetic values and insurmountable challenges. In this work, we report an Rh‐catalyzed reaction between o‐carborane and N‐acyl‐glutarimides to construct various Bcage−C bonds. Under the optimized condition, the removable imine directing group (DG) leads to B(3)− or B(3,6)−C couplings, while the pyridyl DG leads to B(3,5)−Ar coupling. In particular, an unexpected rearrangement of amide reagent is observed in pyridyl directed B(4)−C(sp3) formation. This scalable protocol has many advantages, including easy access, the use of cheap and widely available coupling agents, no requirement of an external ligand, base or oxidant, high efficiency, and a broad substrate scope. Leveraging the RhI dimer and twisted amides, this method enables straightforward access to diversely substituted and therapeutically important carborane derivatives at boron site, and provides a highly valuable vista for carborane‐based drug screening. Rh catalysis was used to enable cross‐coupling between o‐carborane and twisted amide. A series of regioselective B(3,6)−C, B(3,5)−Ar and B(4)−C(sp3) coupling products have been obtained. The operationally simple reaction gives rise to diverse carboranyl‐fused organic motifs and accommodates late‐stage diversification, which may pave a new way for medicinal investigations.