The in situ generated benzyne from benzenediazonium-2-carboxylate 3.7 underwent a [4+2] cycloaddition reaction with the imine formed from aromatic amine and aldehyde to give dihydrophenanthridine. Finally, dehydrogenation in the reaction medium gave the 6-arylated phenanthridine 3.10 in quantitative yields. Annulation of acyloximes with aryne or alkyne has been adopted by Zhu and co-workers (Scheme 3.4). Among a series of palladium catalysts allyl-palladium complex (APC) along with a bulky phosphine ligand were the most promising catalytic system. The oxidative palladium insertion into the N-O bond of acyloxime 3.17