Palladium(II)-Catalyzed C(sp2)–H Bond Activation/C–N Bond Cleavage Annulation of N‑Methoxy Amides and Arynes

The Pd­(II)-catalyzed C–H bond activation/C–N bond cleavage annulation reaction of N-alkyoxyamide aryne is developed to synthesize 9,10-dihydrophenanthrenone derivatives. This reaction exhibited good functional group compatibility with yields up to 92%. Detailed mechanistic studies showed that the key to C–N bond cleavage is the formed eight-membered palladacycle intermediate undergoing nucleophilic addition to the carbonyl group, which provides a new and practical way for N-alkoxyamide directed C–H bond activation.