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Homoconjugated dienes can be rearranged into conjugated 1,3-dienes in the presence of SO2 via ene reactions.Iq2 In the case of norbornadiene (l), which cannot undergo ene reactions with S02, De Lucchi and Lucchini3 reported that it adds to SO2 in a (w& + 7r2, + ~2 , ) fashion4 to give the corresponding sulfolane 2. In our hands, mixtures of 1 and SO2 led only to polymeric material, unless 2,6-di-tert-butyl-p-cresol was added to the reaction mixture (33% yield of 2 after 2 days at 25 "C). We report here that the homocheletropic addition of SO2 is not restricted only to norbomadiene and that it can compete with the usual cheletropic addition (w2, + ~4 , )~ when SO2 is allowed to react with polyenes containing 1,3-diene as well as 1,4-diene moieties.5 When 3,3-dimethylpenta-l,4-diene (3)6 was mixed with 12-13 equiv of SO2 in CH2C12, an 81% yield of sulfolane 47 was obtained after 8 days at 23 OC. Kinetic measurements gave a

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