Catalytic Approach to Diverse α‐Aminoboronic Acid Derivatives by Iridium‐Catalyzed Hydrogenation of Trifluoroborate‐Iminiums

A series of structurally diverse benzyl protected trifluoroborate‐ammoniums were prepared in good to high yields by an efficient hydrogenation of corresponding trifluoroborate‐iminiums using Crabtree's catalyst. Subsequent N‐ and B‐deprotections were demonstrated on selected examples to provide several α‐aminoboronic acids. Preliminary experiments on asymmetric version of the reaction indicated a correlation between E/Z‐ratio in the trifluoroborate‐iminium substrate and enantioselectivity. The broad scope, operational simplicity and efficiency of the presented method imply its high potential for a facile access to libraries of α‐aminoboronic acid derivatives that can be used in medicinal chemistry applications and beyond.