Heterocyclisation of 2,5-diacetyl-3,4-disubstituted-thieno[2,3-b]Thiophene Bis-Thiosemicarbazones Leading to Bis-Thiazoles and Bis-1,3,4-thiadiazoles as Anti-breast Cancer Agents

In this paper, the synthesis of bis-thiazoles and bis-1,3,4-thiadiazoles linked to a thienothiophene nucleus is described. The synthesis was achieved through interaction between 2,5-diacetylthieno[2,3-b]thiophene bis-thiosemicarbazones with a variety of hydrazonyl halides in a basic medium. All the synthesised compounds were characterised by IR, ¹H NMR, ¹³C NMR and mass spectroscopic analyses. The newly synthesised compounds represent a variety of novel polyheteroatomic moieties containing nitrogen and sulfur. Most of the synthesised compounds were evaluated for their antitumour activity against the breast cancer MCF-7 cell line. The results revealed that four compounds are equipotent to tamoxifen (IC₅₀ = 8.04 μg mL⁻¹) with IC₅₀ = 8.23, 8.26, 8.68 and 9.12 μg mL⁻¹ respectively.