Neutral Aromatic 2,3-Diboranaphthalenes

Incorporating isosteric boron units into aromatic frameworks provides access to molecules with unusual electronic structures and reactivity. We report the synthesis of 2,3-diboranaphthalenes (2 and 4), the first neutral diboron analogues of naphthalene featuring an o-diborabenzene core. This electron-rich scaffold exhibits pronounced aromaticity and diverse reactivity. Symmetrical 2 acts as a 6π-aromatic ligand in group 6 metal complexes (5-7) and undergoes double [3 + 2] cycloaddition with CO₂ to afford a fused tetracycle (8). In contrast, unsymmetrical 4 undergoes electrophile-induced ring contraction (9) and oxidative skeletal editing with selenium (10). These findings establish 2,3-diboranaphthalenes as a new class of neutral boron aromatics, broadening the structural and functional space of main-group aromatic systems.