Novel building block, furan-annelated 3-sulpholene; Diels–Alder reactions of 4,6-dihydrothieno[3,4-c]furan s,s-dioxide

Abstract
The preparation of the hitherto unknown 4,6-dihydrothieno[3,4-c]furan S,S-dioxide 1 and its intermolecular Diels–Alder reactions with typical dienophiles are described.