Dihydropyrrole-3-thiones: one-pot synthesis from propargylamines, acyl chlorides and sodium sulfide.

An efficient one-pot synthesis of 1,2,5-trisubstituted-1,2-dihydro-3 H -pyrrole-3-thiones (up to 91% yield), representatives of essentially new heterocyclic systems, by the successive treatment of available propargylamines with acyl chlorides (PdCl 2 /CuI/Ph 3 P/Et 3 N, toluene, 40-45 °C, 3 h) and sodium sulfide (Na 2 S·9H 2 O, EtOH, 20-25 °C, 7 h) has been developed. The synthesis comprises the addition of sulfide anions to the formed aminoacetylenic ketones followed by dehydrative cyclization of the prototropically rearranged adducts.