Copper-Catalyzed Regioselective Dehydrogenative Borylation: A Modular Platform Enabling C4-Borylated 2,1-Borazaronaphthalenes

The [2,1]-borazaronaphthalene scaffold is a valuable BN-isostere of naphthalene with significant potential in medicinal and materials chemistry, yet its precise C4-functionalization remains challenging. Herein, we report a copper-catalyzed, regioselective dehydrogenative borylation that enables direct C4-H borylation of [2,1]-borazaronaphthalenes using B₂pin₂. This method features a broad substrate scope, providing efficient access to diverse 4-boryl derivatives. The synthetic utility is demonstrated through gram-scale synthesis and downstream transformations, including the construction of axially chiral scaffolds, offering a versatile platform for diversifying these BN-heterocycles.