Synthesis and Properties of the Parent Thiophene 1,1-Dioxide

Abstract

Thiophene 1,1-dioxides are synthetically and theoretically important compounds which act as 2π- or 4π-components in a range of cycloadditions. Our recent exhaustive literature survey has revealed that more than 300 papers had appeared on the chemistry of thiophene 1,1-dioxides. Among them, at least 33 papers have described the chemistry of the parent thiophene 1,1-dioxide (1) theoretically or experimentally. However, despite such enormous efforts, 1 has eluded isolation most likely as a result of a rapid cyclodimerization process. Thus, most of the evidence for its existence comes from chemical trapping experiments. We report here the synthesis, isolation, and full characterization of 11 and its monosubstituted derivatives.