An iodine-mediated intramolecular sp3 C-H amination reaction producing quinazolinone-fused polycyclic skeletons from 2-aminobenzamide precursors is reported. This reaction does not use transition metals, has a broad substrate scope, and can be used on a gram scale. Under the optimal reaction conditions, a variety of quinazolinone-fused tetrahydroisoquinolines and derivatives of Rutaecarpine were synthesized from readily accessible compounds. The reaction proceeds well with crude 2-aminobenzamide derivatives, allowing for the synthesis of the products from simple 2-aminobenzoic acids and tetrahydroisoquinolines without purification of the 2-aminobenzamide intermediates. Preliminary biological experiments have identified Cereblon (CRBN) inhibitory activity and relevant anti-myeloma medicinal properties in some of these polycyclic products.