Rhodium(III)‐Catalyzed Intramolecular Annulation through CH Activation: Total Synthesis of (±)‐Antofine, (±)‐Septicine, (±)‐Tylophorine, and Rosettacin

Annulation: The efficient synthesis of 3-hydroxyalkyl isoquinolones and 6-hydroxyalkyl 2-pyridones is enabled through the intramolecular annulation of alkyne-tethered hydroxamic esters (see scheme, Cp*=pentamethylcyclopentadienyl). The reaction features high regioselectivity, broad substrate scope, and excellent functional-group tolerance, proceeds under mild reaction conditions with low catalyst loading, and obviates the need for an external oxidant.