Stereoselective Synthesis of Amido and Phenyl Azabicyclic Derivatives via a Tandem Aza Prins-Ritter/Friedel–Crafts Type Reaction of Endocyclic N‑Acyliminium Ions

A simple protocol is described for the synthesis of amido and phenyl hexahydroindolizin-3­(2H)-one, hexahydro-1H-quinolizin-4­(6H)-one, and 1,3,4,10b-tetrahydropyrido­[2,1-a]­isoindol-6­(2H)-one derivatives via endo-trig (aza-Prins type) cyclization followed by an intermolecular Ritter/Friedel–Crafts reaction of cyclic N-acyliminium ions, which are derived from the boron trifluoride etherate treatment of regioselectively reduced N-homoallyl imides. The reactions are highly diastereoselective with excellent yields.