Acetoacetanilide derivatives 1a-c reacted with either malnonitrile or ethyl cyanoacetate and elemental sulfur to give the thiophene derivatives 3a-f. The reactivity of 3a towards some chemical reagents to give thiophene, theino[2,3-b]pyridine, thieno[2,3-c]pyrimidine and coumarin derivatives was studied. The anti-tumor evaluation of the newly synthesized compounds against the three human tumor cells lines namely breast adenocarcinoma (MCF-7), non-small cell lung cancer (NCI-H460) and CNS cancer (SF-268) showed that compounds 8a, 8b and 14 exhibit higher inhibitory effects towards the three tumor cell lines than the positive control doxorubicin.