Synthesis and characterization of novel heterosubstituted pyrroles, thiophenes, and furans

Abstract

Sixteen new compounds, including novel five-membered heterocyclic systems (pyrrole, thiophene, or furan) linked to imidazole, thiazole, or quinoline rings are reported. The intermediate 1,4-diketones were synthesized via the Stetter reaction in the presence of thiazolium salt as a catalyst. Cyclization reactions of the 1,4-dicarbonyl compounds with polyphosphoric acid, ammonium acetate or Lawesson's reagent by the Paal-Knorr synthesis, afforded unknown 2,5-disubstituted furan, pyrrole, or thiophene compounds in moderate yields, respectively. The structures of the synthesized compounds were confirmed by IR, H-1 NMR, C-13 NMR, and elemental analysis.