A series of thieno[2,3-d]- and thieno[3,2-d]pyrimidines have been easily synthesized using as key step a deproto-cadmiation–trapping sequence. Some of the compounds thus synthesized were screened for anticancer (cytotoxic) activities, and (S)-2-(6-iodo-2-phenylthieno[2,3-d]pyrimidin-4-ylamino)-3-phenylpropanoic acid proved to have a significant activity towards liver, human breast and cervix carcinoma cell lines.