(2-Iodoaryl)allenes are versatile 4C-components in palladium catalysed [4+2] cycloaddition reactions with norbornene, 2-aza-3-oxonorbom-5-ene, and allene acting as 2C-components. A variety of dihydronaphthalenes and naphthalenes are produced in excellent yield. Copyright (C) 1996 Elsevier Science Ltd