FURAN-FUSED 3-SULFOLENE AS A NOVEL BUILDING-BLOCK - INTERMOLECULAR DIELS-ALDER REACTIONS OF 4H,6H-THIENO[3,4-C]FURAN 5,5-DIOXIDE

A furan-fused 3-sulfolene 4N,6H-thieno[3,4-c]furan 5,5-dioxide 1, can be used as a bis-diene, reacting sequentially with a variety of dienop hiles to construct four types of skeleton, depending on the dienophile and the reaction conditions. The 3-sulfolene moiety of the furansulfo lene not only functions as the s-cis-diene part in Diels-Alder reactio ns, but also extends the range of the Diels-Alder reactions of the fur an moiety with various dienophiles through its desulfonylation to form the s-cis-diene.