A palladium-catalyzed cascade reaction of 2'-acetyl-[1,1'-biphenyl]-2-carbonitriles with arylboronic acids is developed. This reaction affords a new class of seven-membered 5-arylidene-7-aryl-5H-dibenzo[c,e]azepines with good functional group compatibility and selectivity. Reaction mechanistic study suggests that this transformation involves carbopalladation of nitrile and subsequent intramolecular cyclization followed by oxidative Heck coupling.