Generation and Trapping of Phosphorus Stabilized 4,5-Ethylenedithio-1,3-dithiol-2-ide Carbanions: Synthesis of Ethylenedithio-1,3-dithiafulvalenes

2-Dimethoxyphosphoryl-5,6-dihydro-1,3-dithiolo[4,5-b][1,4]-2-dithiin (8) and 2-triphenylphosphonio-5,6-dihydro-1,3-dithiolo-[4,5-b][1,4]dithiin tetrafluoroborate (9) have been obtained in four steps from 4,5-ethylenedithio-1,3-dithiole-2-thione (4) (ca. 75% overall yield). Deprotonation of (8) and (9) yields the corresponding carbanion (10) and ylide (11) which have been trapped in good yield with glyoxal, cyclopentanone and anthraquinone to afford ethylenedithio-1,3-dithiafulvalenes.