Ruthenium(II)‐Catalyzed C−H Activation/Annulation of Aromatic Hydroxamic Acid Esters with Enamides Leading to Aminal Motifs

Hydroxamic acid ester directed C(sp2)−H activation/annulation strategy has been reported employing electron‐rich enamides under Ru(II)‐catalysis to access aminal frameworks. Both N‐vinyl acetamide and N‐vinyl formamide delivered aminals bearing dihydroisoquinolinone motif in good yields. Under modified reaction conditions, vinyl acetate bestowed the selective formation of 3,4‐unsubstituted isoquinolones. The protocol operates under mild conditions, where the C−H ruthenation step is reversible and apparently not the rate‐determining step. An annulative coupling between aromatic hydroxamic acid esters and electron‐rich olefins such as enamides has been developed for the production of valuable aminal frameworks under inexpensive ruthenium catalysis.