Iridium(III)-catalyzed remote B(9)-H alkylation of o-carboranes with nitrile template.

Abstract

Carboranes, unique three-dimensional analogs of benzene, have attracted considerable attention owing to their potential in medicine, catalysis, and materials science. Consequently, the introduction of functional groups into carborane clusters has emerged as an important research focus. While directing group-assisted ortho-B-H activation of o-carboranes is well established, meta-B-H functionalization remains rare. Here we show iridium(III)-catalyzed remote B(9)-H alkylation of o-carboranes using a nitrile-based directing template. Optimized template design is critical for achieving high efficiency and regioselectivity, as confirmed by experiments and density functional theory calculations. The method tolerates diverse functional groups, operates under simple conditions, and employs a removable template readily derived from o-carborane carboxylic acids. This approach enables scalable access to structurally diverse B(9)-alkylated o-carboranes for further synthetic elaboration.