Synthesis and antiviral screening of 2‐(propylthio)‐7‐substituted‐thiazolo[5,4‐d]pyrimidines as anti‐bovine viral diarrhea virus agents

7‐Chloro‐2‐(propylthio)thiazolo[5,4‐d]pyrimidine 4 was prepared and used as a precursor for synthesizing new derivatives of thiazolo[5,4‐d]pyrimidine through the nucleophilic displacement of the chlorine atom by different types of amino derivatives. Reaction of compound 4 with primary and secondary amines produced the corresponding substituted amino derivatives. Reaction of 4 with hydrazine hydrate then followed by condensation with aromatic aldehydes afforded hydrazone derivatives. Reaction of 4 with hydrazine hydrate then followed by reaction with isothiocyanates gave the disubstituted thiosemicarbazides. Finally, treatment of 4 with hydrazine derivatives afforded the novel disubstituted hydrazine derivatives. Preliminary antiviral screening on the bovine viral diarrhea virus (BVDV) was carried out, which was classified as a member of the same family of Hepatitis C virus. The results indicated that some of the tested compounds exhibited anti‐BVDV activity which may be suitable for a new lead molecule to design more potent anti‐BVDV agents.