“…Another class of reducing agents that is routinely utilized for reductive amination is amine boranes, such as pyridine-borane, − 2-picoline-borane, , dimethylamine-borane, N -isopropyl- N -methyl- tert -butylamine-borane, 5-ethyl-2-methylpyridine-borane, and benzylamine-borane . With these reagents, an equivalent of the amine from the reductant remains in the product mixture, necessitating their difficult separation from the desired product amine.…”