Intramolecular Cyclization with Nitrenium Ions Generated by Treatment of <i>N</i>-Acylaminophthalimides with Hypervalent Iodine Compounds: Formation of Lactams and Spiro-Fused Lactams
N-Phthalimido-N-acylnitrenium ions are generated from N-acylaminophthalimides, a new class of precursors, by treatment with hypervalent iodine compounds (PIFA and HTIB). In HFIP, the nitrenium ions undergo intramolecular electrophilicsubstitution reactions to afford N-aminonitrogen heterocycles in high yields. In TFEA, spirodienones bearing the 1-azaspiro[4.5]decane skeleton are obtained by treatment