Cascade Iodine-Catalyzed Synthesis of Nitrogenated Aromatics from 2-Pyrones.

Herein, we report an improved strategy for the synthesis of nitrogen-containing aromatic compounds featuring a nitrogen atom directly attached to a benzene ring. The method relies on a thermal one-pot Diels-Alder/decarboxylation/iodine-catalyzed aromatization cascade reaction starting from 2-pyrones, enabling access to novel C-3-nitrogenated phthalimides and related aromatics in yields of up to 95%. Iodine, a simple and readily available catalyst, was employed to promote the transformation while effectively suppressing the competing second Diels-Alder reaction. Subsequent derivatization demonstrated the synthetic utility of this approach through the preparation of pomalidomide, an immunomodulatory drug.