We describe herein a palladium-catalyzed tandem oxidative arylation/olefination reaction of aromatic tethered alkenes/alkynes for the synthesis of dihydrobenzofurans and 2 H-chromene derivatives. This reaction features a 1,2-difunctionalization of C−C π-bond with two C−H bonds using O2 as terminal oxidant at room temperature. The products obtained are valuable synthons and important scaffolds in biological agents and natural products.