Readily Available Primary Aminoboranes as Powerful Reagents for Aldimine Synthesis

Primary aminoboranes (RNHBR2), which are readily available by spontaneous dehydrocoupling of amines and boranes cleanly react at room temperature with aldehydes to give aldimines. The overall transformation from amines to aldimines can be conveniently performed by a sequential one‐pot reaction. This synthetic strategy is especially useful for electron poor and bulky amines which are reluctant to react with aldehydes under dehydration conditions. Using a Glorius robustness screen, we show that this methodology is chemoselective, and functional group tolerant. Computational and experimental data support the irreversible formation of the aldimine product in marked contrast with traditional methods. Simple and powerful: Primary aminoboranes (RNHBR2) are powerful tools for the chemoselective, functional‐group tolerant, and widely applicable synthesis of aldimines. According to DFT calculations and experimental methods, this reaction proceeds in a non‐reversible way that is orthogonal to, and outperforms, conventional dehydration methods.