Synthesis of furan-, thiophene- and pyrrole-fused sultines and their application in Diels–Alder reactions

Abstract
The synthesis of 1,4-dihydrofurano[3,4-d]-3,2-oxathiine 2-oxide 8, 5,7-dimethyl-1,4-dihydrothieno[3,4-d]-3,2-oxathiine 2-oxide 9 and 1,4-dihydro-6-tosylpyrrolo[3,4-d]-3,2-oxathiine 2-oxide 10, precursors for nonclassical heteroaromatic o-quinodimethanes, and their application in the Diels–Alder reactions are reported.