The generation of 2,3-dihydro-2,3-bis-(methylene)thiophenes from 4,6-dihydrothieno[3,4-b]thiophene 5,5-dioxides

Article abstract of DOI:10.1016/S0040-4039(00)88841-3

On heating in sulpholane 4,6-dihydrothieno[3,4-b]thiophene 5,5-dioxides give 2,3-dihydro-2,3-bis(methylene)thiophenes which can be intercepted in Diels-Alder reactions. Sulphur dioxide is a very efficient trap for these thiophene xylylenes giving the cycl