Nickel-Catalyzed Fourfold Cascade Cage BH Arylation of <i>o</i> -Carboranes

While site-selective cage B–H functionalization of carboranes using noble-metal catalysts is well established, there is still a pressing need for new protocols that meet the sustainability and efficiency standards of modern synthesis. Leveraging the earth abundance, low cost, and minimal toxicity of 3d metals, we present herein a nickel-catalyzed, directing-group-assisted tetra-arylation of cage BH in o -carborane. This reaction occurs at B(3,4,5,6) without the need for any external oxidant and yields a class of tetra-aryl products in very high yield. Density functional theory (DFT) studies reveal a stepwise metalation sequence of B(4) → B(5) → B(3) → B(6), providing a practical, one-pot alternative for constructing densely arylated o -carboranes.