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.