Carbon Dioxide-Mediated Preparation of Amine-Boranes

Since their discovery by Burg and Schlesinger in 1937, amine-boranes have enjoyed a rich preparative history and have experienced reinvigorated interest as valuable reagents for organic syntheses. Previously, the Herbert C. Brown Center for Borane Research has reported their synthesis from NaBH₄ and amines via the intermediacy of (NH₄)₂SO₄ or NaHCO₃. Described herein is a CO₂-mediated amine-borane synthesis that accommodates all classes of amines, particularly long-chain trialkyl- and pyridine-like heteroarylamines.