A Regiodivergent Dearomative Trifunctionalization of Quinolinium Salts to Access Fused Tetrahydroquinoline Polycycles

Dearomative trifunctionalization of quinolinium salts is one of the most straightforward approaches to access biologically relevant multisubstituted tetrahydroquinolines. However, research in this field is still in its infancy. Here, we report a base-controlled regiodivergent dearomative trifunctionalization strategy for transforming quinoliniums into two kinds of structurally intriguing tetrahydroquinoline polycycles through a one-pot three-component cascade annulation. The key is the <i>in situ</i> generation of a "Nu-E-Nu" trifunctional reagent that can precisely identify the matched reactive sites of quinoliniums.