Tetrakis(alkylthio)thieno[3,4-c]thiophene: Synthesis, stability, and reactivity

Article abstract of DOI:10.1002/jhet.5570250238

The synthesis of tetrakis(alkylthio)thieno[3,4-c]thiophenes 1a-e by the dimerization reaction of bis(alkylthio)cyclopropenethiones is described. The remarkable thermodynamic and kinetic stability suggests the significant electron-accepting conjugation of the alkylthio substituents to the carbanionic 1,3,4, and 6 carbons in the framework. The isopropylthio- and ethylthio-substituted thienothiophenes 1d and 1e undergo cycloaddition reactions with dienophiles such as N-phenylmaleimide and dimethyl acetylenedicarboxylate to give the cycloadducts in moderate yields.