Direct Decarboxylative Borylation via Radical-Organometallic Relay.

Alkyl boronic acids and esters are indispensable building blocks in synthesis, medicinal chemistry, and materials science, yet direct access to structurally diverse alkyl organoboron compounds remains scarce. Carboxylic acids would be ideal precursors owing to their abundance and structural diversity, but their direct conversion into organoboron compounds remains elusive. This longstanding challenge stems from an intrinsic redox incompatibility between oxidative decarboxylation and conventional borylation chemistry. Here, we report a direct decarboxylative borylation of native carboxylic acids enabled by a radical-organometallic relay strategy. The reaction proceeds without substrate preactivation and is applicable to primary, secondary, and tertiary carboxylic acids, exhibiting broad functional group tolerance and enabling late-stage borylation of pharmaceuticals and peptides. By resolving a fundamental redox incompatibility, this work establishes a new reaction paradigm in which oxidative radical generation is directly integrated with organometallic C-B bond formation.