The 1-Phenylsulfonylallenyl Terminus in Intramolecular Diels-Alder Reactions: Tether Length and Reactivity.-The reactivity of tetraenes (Ia)-(Id) concerning their cycloaddition behavior is investigated. In the case of (Ia)-(Ic), cycloadducts are available under conditions which depend on the tether length.The attempt to oxidize sulfoxide (VII) to (Id) fails. When the reaction mixture obtained from MCPBA treatment of (VII) is maintained in CH 2 Cl 2 for 20 min, cycloadducts (VIII) and (IX) are isolated thus confirming their partial formation during the oxidation step. The expected intermediate (Id) is not identified at any time.-(BULL, JAMES R.; GORDON, RICHARD S.; HUNTER, ROGER; Synlett (1999) 5, 599-601; Dep. Chem., Univ. Cape Town, Rondebosch, Cape Town 7701, S. Afr.; EN)