One-pot synthesis of 3H-1,2-dithiole-3-thione derivatives from dithiolmalonic esters

The reaction of dithiolmalonic esters with P2S5/S8 in boiling xylene and with 2-mercaptobenzothiazole/ZnO as catalyst produces 5-R (R=alkyl or aryl) thio-3H-1,2-dithiole-3-thiones as the major identifiable product. The use of Lawessonʹs reagent as sulfurizing agent gives even better yields. For instance with R=phenyl the yield rises from 44 to 82%.