Nitrogen-Only Fused Polycyclic Targets

3 FUSED POLYCYCLIC TARGETS 3.3.1 Nitrogen-Only Fused Polycyclic Targets 

The synthesis of tetrahydroquinolines has received a great deal of attention owing to their presence in many natural frameworks and also to their pharmacological importance [59], Enantioselective [4 -1- 2] cycloadditions constitute one of the most widely employed tools for the preparation of six-membered nitrogen heterocycles [60], Among them, the Povarov reaction is one of the main approaches to 

The first enantioselective, three-component Povarov reaction was reported in 2009 by Zhu. Anilines, aldehydes, and enecarbamates, acting as electron-rich olefins, afforded derivatives of 4-aminotetrahydroquinolines with excellent enantio ( 99% ee) and diastereoselectivities ( 99% cis), the reaction being catalyzed by a chiral phosphoric acid derived from Hg-BINOL 81. The reaction could be 

Although both Akiyama and Zhu used similar Br0nsted acid catalysts, both derived from i -BINOL, the absolute stereochemistry for both stereocenters at C-2 and C-4 was the opposite in both cases, and this was attributed to different bonding 

Nelson has reported a three-component synthesis of piperidines and more complex fused heterocycles based on a sequence of reactions starting from compound 88, alkenes, and C-nucleophiles (e.g., allyltrimethylsilane), and comprising the 

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