A palladium-catalyzed domino N-benzylation/intramolecular direct arylation involving sulfonanilides and 2-bromobenzyl bromides has been developed for the first time, providing a workable access to N-sulfonyl dihydrophenanthridines in good to excellent yields. Under the optimized conditions, the formation of 5,6-dihydrophenanthridines was largely controlled over the formation of biaryl sultams containing a seven member ring. The optimized condition was found extendable to the regiocontrolled domino formation of N-sulfonyl-6,7-dihydro-5H-dibenzo[c,e]azepines over the biaryl sultam formation. Using an appropriate substrate, a biaryl sultam has been obtained exclusively.