Metal-Free Hydrogenation of N-Phenyl Aromatic Rings

Stephan et al. have reported metal-free hydrogenation of N-substituted aniline using H₂ and B(C₆F₅)₃.¹⁾ Sterically encumbered Lewis acid (B(C₆F₅)₃) and Lewis base (N-substituted aniline) are combined to form the unquenched “frustrated Lewis pairs (FLPs)²⁾” which is available to carry out unusual reactions. In this reaction, the boron mediates uptake of H₂, terminating with a final FLP activation of H₂ to enable the hydrogenation to proceed under metal free conditions.