Hypervalent Iodine-Mediated Intramolecular trans-Aminocarboxylation and Oxoaminocarboxylation of Alkynes: Divergent Cascade Annulations of Isocoumarins under Metal-Free Conditions

An exclusive trans-aminocarboxylation and oxoaminocarboxylation of diarylalkynes were realized through hypervalent iodine-mediated cascade annulations under metal-free conditions, leading to divergent assembly of fused or spiro polycyclic heterocycles with a dosage of the hypervalent iodine oxidant. The mechanisms for the formation of both products are proposed.