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.