Neutral and Anionic Diboron Compounds Bearing Electron‐Precise B−B Bond

Abstract Electron‐precise B−B bonded compounds are valuable reagents in organic syntheses, which can be used as key starting material for the synthesis of functionalized organoboranes. Bis(pinacolato)diborane(4) B 2 pin 2 and its derivatives are among the most studied diboron species. However, their B−B bonds usually need to be activated by transition metal catalysts or bases for further transformations. Recently, many well‐designed/reactive electron‐precise B−B bonded compounds have been developed, which could facilitate direct reactions with small molecules, unsaturated substrates, and electrophiles. This review highlights the synthesis, structure, and reactivity of neutral and anionic B−B bonded compounds.