A Regiodivergent Dearomative Trifunctionalization\nof Quinolinium Salts to Access Fused Tetrahydroquinoline Polycycles

Dearomative\ntrifunctionalization of quinolinium salts is one of\nthe most straightforward approaches to access biologically relevant\nmultisubstituted tetrahydroquinolines. However, research in this field\nis still in its infancy. Here, we report a base-controlled regiodivergent\ndearomative trifunctionalization strategy for transforming quinoliniums\ninto two kinds of structurally intriguing tetrahydroquinoline polycycles\nthrough a one-pot three-component cascade annulation. The key is the <i>in situ</i> generation of a “Nu–E–Nu”\ntrifunctional reagent that can precisely identify the matched reactive\nsites of quinoliniums.