Photochemical reactions of phenylacetylenes with ethylene trithiocarbonate. Synthesis of phenyl-substituted 2-thioxo-1,3-dithioles

Abstract

A novel photochemical synthetic route to phenyl-substituted 2-thioxo-1,3-dithioles (TDT), intermediates in the synthesis of tetrathiafulvalenes (TTF), starting from ethylene trithiocarbonate (ETC) and phenylacetylenes is described. Phenyl- and diphenyl-acetylene and 1-phenylpropyne reacted with ETC derivatives in reasonable yields. The fluorescence of the acetylenes was quenched by ETC via a trivial process: sensitization with benzophenone and quenching with air suggested that the reaction proceeded mainly through the triplet excited states of the acetylenes. Irradiation of ETC alone with light of longer wavelength and quenching experiments suggested that the excited singlet state of ETC also participated in the reaction, in a minor process.