Diverse reactions of nitrogen-containing compounds with hydrosilanes catalyzed by B(C6F5)3

Despite being a boron Lewis acid, tris(pentafluorophenyl)borane [B(C6F5)3] exhibits completely different catalytic behavior in hydrosilane reactions compared to conventional boron trihalides. Extensive evidence demonstrates its ability to directly activate hydrosilanes, forming an η1-coordinated borane-silane adduct [R3Si–H–B(C6F5)3]. Since PIERS first disclosed this unique activation mechanism and successfully applied it to the hydrosilylation of carbonyl compounds in 1996, B(C6F5)3 has gained considerable attention as a catalyst for the metal-free activation of hydrosilanes. The early application of this catalytic system was primarily focused on reductive transformations of oxygen-containing compounds. In recent years, the application has been extended to nitrogen-containing compounds, achieving notable success. In addition to reducing a variety of nitrogen-based functional groups, the B(C6F5)3/hydrosilane system has shown remarkable efficacy in silylation reactions and the activation of C–N bonds. Moreover, the versatility of B(C6F5)3 makes this system readily integrate with other B(C6F5)3-mediated processes, enabling tandem reactions that rapidly construct molecules with structural complexity and functional diversity. This dissertation not only summarizes the significant advancements in this field but also provides a detailed account of several novel transformations we have developed using the B(C6F5)3/hydrosilane catalytic system. These include the denitrogenation of aromatic nitriles, as well as ring-opening and ring-contraction reactions of cyclic amines, and the skeletal reorganization of acyclic amines. Each of these new transformations underwent systematic optimization, demonstrating that all of them can be efficiently accomplished with only catalytic amounts of B(C6F5)3 and commercially available hydrosilanes under operationally simple conditions. Comprehensive investigations into the substrate scope were conducted to define the specific limitations of these methodologies. Moreover, based on the results of mechanistic studies, the respective reaction pathways were proposed. Despite their differences, the first step in all transformations is the formation of the key η1-[R3Si–H–B(C6F5)3] adduct.