In a simple one-pot procedure, treatment of 2-amino-3-cyanothiophenes with Lawesson's reagent (LR) leads to the new thieno[2,3-d][1,3,2]diazaphosphorine-6-thione-2-sulfides in good to excellent yields. A possible reaction mechanism, involving a Dimroth-type rearrangement, is proposed. The structure of obtained products was confirmed by NMR (H-1, P-31, and C-13) and IR spectroscopies and by mass spectrometry. [GRAPHICS] .