The Chemistry of Thienopyrimidines

The chapter analyzes the results of studies on the synthesis, chemical transformations, and biological activities of thienopyrimidines. The known approaches to the synthesis of thienopyrimidines can be divided into two main groups: construction of the pyrimidine ring by intramolecular cyclization of thiophene derivatives and thiophene ring closure in pyrimidine derivatives. The starting thienylureas are synthesized according to known procedures based on the reactions of aminothiophenes with isocyanates, KOCN–HC1, C1SO2NCO, and some other reagents. In the synthesis of thienopyrimidines by thiophene ring, closure data are systematized according to the types of reactions giving rise to the thiophene ring. Pyrimidines starting compounds can be prepared by two methods. One of them involves substitution of the mercaptoacetic acid residue for the chlorine atom in 4-chloro-5-ethoxycarbonylpyrimidines. Another procedure for the synthesis of pyrimidines involves alkylation of 5-ethoxycarbonylpyrimidine-4(3H)-thiones with chloroacetic acid derivatives. The chemical properties of thienopyrimidines are also discussed in the chapter, where nucleophilic substitution and electrophilic substitution are described. The chapter then turns to the discussion of biological activity and some aspects of the practical use of thienopyrimidines. Certain thienopyrimidine derivatives exhibit antiallergic, antiatherosclerotic, antibacterial, anticancer, antiviral, antihypertensive, antidepressant, antihistaminic, antimicrobial, spasmolytic, analgetic, antiinflammatory, neurotropic activities, and many more. Finally, the chapter concludes by stating the analysis of the data on the chemistry of isomeric thienopyrimidines that shows that this attracts increasing interest of the chemists and biochemists.