Synthetic tetstudies in the intramolecular carbocyclization of N-acyloxyiminium ions: Stereoelectronic and steric implications of nucleophilic alkene, alkyne, and allene hers

The extension of carbocyclizations of C-tethered N-acyloxyiminium ions with substituted alkene, alkyne and allene tethers to give novel azacyclic ring systems is reported. It is shown that the carbocyclization of mixed allene/alkene/alkyne tethers favors reaction of the allene, leading to the preferential formation of relatively strained hydrooxazinones rather than the corresponding hydroindoles.