The synthesis of novel thieno[3,2-d]pyrimidine derivatives commenced with 5-bromo-2-chlorobenzonitrile with ethyl-2-mercaptoacetate, which yielded the compound AT-2. The addition of piperidin-2-one to the formed AT-2 and subsequent cyclization yielded the compound AR-05. Subsequently, the Suzuki cross-coupling reaction was employed to facilitate the formation of a carbon-carbon bond. The intermediate AR-05 was formed in an alkaline medium in a toluene/water mixture in the presence of arylboronic acid and a palladium catalyst, forming a new C-C bond. AR-27 was synthesized as the final product. The structure of the new compounds was studied by analyzing the results obtained through the investigation of their physical and physicochemical properties.