Iodine-Induced Transannular Coupling of 1,6-Cyclodecadiyne.

Treatment of 1,6-cyclodecadiyne (1) with one equivalent of iodine in ether leads to regioselective transannular coupling, producing 1,5-diiodo-2,3,4,6,7,8-hexahydronaphthalene (2) in excellent yield. Solvent-incorporation products are observed in addition to 2 when the reaction is done in benzene, chlorobenzene, or methanol. Bromination of 1 gives analogous products, but the reaction is not as clean.