Catalytic Double Hydrosilylation and Hydroboration of Pyridines and Quinolines

Pyridines and quinolines are foundational motifs for synthesizing bioactive N‐heterocycles. While dearomative single hydrofunctionalization (FG = Si, B) of N‐heteroarenes to yield dihydropyridines/quinolines (DHP/DHQ) is well‐established, achieving regioselective double hydrofunctionalization—specifically controlling the second C(sp 3 )FG bond‐forming step—remains a significant challenge. This minireview highlights advancements in Lewis acidic organoborane and transition‐metal catalysis for the direct synthesis of functionalized tetrahydropyridines (THP) and tetrahydroquinolines (THQ) scaffolds. We provide a comprehensive analysis of substrate scopes, reaction mechanisms, and the origins of selectivity, contrasting the intrinsic electronic control of boron systems with the ligand‐controlled pathways of Rh and Co catalysts. Finally, we offer some perspectives on utilizing well‐defined heterogeneous catalysts and expanding these cascade protocols to broader conjugated systems, such as α , β ‐unsaturated carbonyls and dienes, through highly modular catalyst design.