Palladium(II)-Catalyzed C(sp 2 )-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.