4,6:12,14‐Di(1,3‐adamantano)‐1,9‐dithiacyclohexadecane (1), 4,6:12,14:20,22‐tri(1,3‐adamantano)‐1,9,17‐trithiacyclotetracosane (2), and 5,7:14,16‐di(1,3‐adamantano)‐1,2,10,11‐tetrathiacyclooctadecane (3) have been obtained by intermolecular cyclization of 1,3‐bis(2‐bromoethyl)adamantane (4) with thioacetamide using a high‐dilution technique. The reaction is concentration‐dependent. The crystal structures of 1, 2, and 3 have been determined by single‐crystal X‐ray diffraction.